Articles de revues : « Functional antibody titers »

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Schaller, Monica, Irmela Sulzer, Magnus Mansouri, MD student, Bernhard Lämmle et Johanna A. Kremer Hovinga Strebel. « Anti-ADAMTS13 Inhibitor Boosting During Plasma Exchange Therapy in Acquired TTP Is the Expression of a General Dysregulation of the Immune Response »,. Blood 118, n^o 21 (18 novembre 2011) : 3299. http://dx.doi.org/10.1182/blood.v118.21.3299.3299.

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Abstract Abstract 3299 Background. Thrombotic thrombocytopenic purpura (TTP) is a rare disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia with schistocytes on the peripheral blood smear and a variable degree of ischemic organ dysfunction due to microvascular thrombosis. In the case of acquired TTP, circulating autoantibodies inhibit ADAMTS13 activity and/or increase ADAMTS13 clearance. The first-line treatment of an acute TTP bout is plasma exchange (PEX) therapy with the replacement of fresh frozen plasma. Up to 30% of TTP patients show an exacerbation under PEX. After initial improvement, platelet counts drop again which is typically associated with a strong increase of ADAMTS13 inhibitor titers, and therefore the phenomenon is also referred to as inhibitor boosting. Interestingly it is apparently not seen in other autoimmune diseases treated with PEX, like acquired hemophilia A or myasthenia gravis. The aim of this study was therefore to investigate if inhibitor boosting in acquired TTP is a general or ADAMTS13 specific phenomenon. Methods. Plasma samples, obtained day-to-day during PEX therapy supplemented with steroids until remission, of 9 patients suffering from acute TTP due to severe acquired ADAMTS13 deficiency, were analyzed for the following laboratory parameters: (a) C-reactive protein (CRP) and total IgG, (b) ADAMTS13 activity, (c) anit-ADAMTS13 antibody titers by ELISA, (d) functional inhibitor titers by FRETS assay, and (e) anti-TG and anti-TPO antibody titers. Results. At initial presentation inhibitor titers ranged from 0.7 - >10 BU/ml (a positive functional inhibitor titer is defined as >0.4 BU/ml by FRETS). All patients initially improved when PEX was started, however, in 7/9 cases a drop in platelet count was noted on day 7 (n=5), 8 or 9 (each n=1), which was associated with a substantial increase in anti-ADAMTS13 antibody and functional inhibitor titer in all seven patients. CRP was increased (>30mg/L) in one patient only, during the three days before the raise in inhibitor titer and a drop in platelet count was noted, while total IgG remained stable in all 9 patients throughout PEX. At presentation none of the patients had a positive result for the thyroid antibodies, however, all 9 patients developed positive anti-TPO antibody titers during treatment and three patients tested positive for anti-TG antibodies at the same time. Anti-TPO antibody peaks occurred after the anti-ADAMTS13 antibody peak in all patients (range days 9–17), except the two patients where no raise in anti-ADAMTS13 antibody titers was observed (anti-TPO peak on day 3 in both). The two patients without inhibitor boosting required only five and six PEX sessions, respectively to get into remission, of the other seven patients two didn't overcome the inhibitor boosting and became refractory and were subsequently successfully treated by splenectomy or Rituximab, and one patient died of sepsis on day 11. Conclusions. Inhibitor boosting in acquired TTP due to antibody-mediated severe ADAMTS1313 deficiency treated with PEX is common (78%) and cannot be overcome by standard first line treatment in half of the patients. The fact that significant titers of other autoantibodies than anti-ADAMTS13 antibodies occur during the acute disease episode is striking and points to a more general dysregulation of the immune response in acquired TTP. Investigation of further autoantibodies, cytokines, etc. to explore the role of B-cells and T-cells in this phenomenon in more detail are underway. Disclosures: No relevant conflicts of interest to declare.

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Plaimauer, Barbara, Claudia Juno et Friedrich Scheiflinger. « In Vitro Efficacy of Recombinant ADAMTS13 in Acquired TTP Patients with Anti-ADAMTS13 Inhibitory Antibody. » Blood 112, n^o 11 (16 novembre 2008) : 2295. http://dx.doi.org/10.1182/blood.v112.11.2295.2295.

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Abstract Thrombotic thrombocytopenic purpura (TTP) is associated with a severe functional deficiency of the ADAMTS13 metalloprotease resulting in accumulation of highly adhesive ultra-large von Willebrand factor (ULVWF) multimers. ULVWF promote spontaneous platelet clumping eventually leading to life-threatening widespread microvascular thrombosis in multiple organs. Inhibitory and non-inhibitory anti-ADAMTS13 autoantibodies that result in functional deficiency and/or accelerated in vivo clearance of ADAMTS13 have been detected in patients suffering from acquired idiopathic TTP. Current treatment with plasma exchange therapy is considered to remove the autoantibodies and to replenish plasma with the deficient protease. While researching therapeutic recombinant ADAMST13 (rADAMTS13) as a possible treatment modality for TTP patients, we investigated the in vitro potency of rADAMTS13 to overwhelm and neutralize circulating anti-ADAMTS13 antibodies and concurrently to reinstate plasma ADAMTS13 to normal. Mixing and incubating patient plasma with normal reagent plasma and subsequent FRETSVWF73 activity analysis was used to calculate the individual anti-ADAMTS13 inhibitor titers in 36 untreated idiopathic TTP patient plasma samples with severe ADAMTS13 deficiency (<10% of normal). The inhibitor titers (IU/ml) ranged from 1.5 to 85IU/ml (median of 3.75 IU/ml). To compare the performance of the different patient samples at equal inhibitor titers, we diluted each sample to predefined inhibitor titers (e.g. in patient samples with inhibitor titers <10IU/ml we diluted to 1, 3, 6 and 9IU/ml). Then, incrementally increasing concentrations of purified rADAMTS13 derived from stably transfected CHO cells were added to each pre-set inhibitor titer done for each of the 36 patient samples. Complex formation of rADAMTS13 and anti-ADAMTS13 patient antibody was allowed and the remaining ADAMTS13 activity was analyzed. The input of rADAMTS13 required to saturate circulating inhibitors and to elevate the activity level up to 1U/ml in the plasma was calculated by regression analysis. Our data indicate a linear correlation between supplemented rADAMTS13 and anti-ADAMTS13 antibody titer (for titers <10IU/ml) suggesting that rADAMTS13 should be further investigated as a possible treatment of acquired TTP.

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Tapia, Olga, Anatoly Slepenkin, Evgueni Sevrioukov, Kathi Hamor, Luis M. de la Maza et Ellena M. Peterson. « Inclusion Fluorescent-Antibody Test as a Screening Assay for Detection of Antibodies to Chlamydia pneumoniae ». Clinical and Vaccine Immunology 9, n^o 3 (mai 2002) : 562–67. http://dx.doi.org/10.1128/cdli.9.3.562-567.2002.

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ABSTRACT A study was conducted to determine the ability of the inclusion immunofluorescence assay (inclusion IFA) to act as a screening test to detect samples with antibodies to Chlamydia pneumoniae; microimmunofluorescence (MIF) was used as the “gold standard.” In addition, the inclusion IFA was compared using HEp-2 cells infected with either C. pneumoniae CM-1 or Chlamydia trachomatis serovar E. A total of 331 serum samples representing a range of MIF titers were evaluated. The sensitivities of the inclusion IFA for detecting samples with C. pneumoniae MIF titers of ≥16 were 96.9 and 74.8% with C. pneumoniae- and C. trachomatis-infected cells, respectively. For samples with an elevated C. pneumoniae MIF titer of ≥512, the sensitivities of the C. pneumoniae- and C. trachomatis-based inclusion IFA were 97.0 and 8.8%, respectively. These results suggest that the inclusion IFA is not a genus-specific test, as evidenced by the failure of the C. trachomatis-infected cells to detect a significant number of samples with C. pneumoniae antibodies. Samples that had elevated C. pneumoniae inclusion IFA and MIF titers but that were found negative (titer, <16) by the C. trachomatis inclusion IFA were further tested by an in vitro neutralization assay for functional antibodies that might not have been detected by the serological assays. The in vitro neutralization results corroborated the serological results in that all seven sera tested had a neutralization titer for C. pneumoniae (range, 20 to 225), while all but one failed to have any effect on the infectivity of C. trachomatis serovar E. While the C. pneumoniae inclusion IFA had a high sensitivity for detecting chlamydial antibodies, depending on whether it was used as a screening test for detecting samples with low (≥16) or elevated (≥512) MIF titers, its specificity ranged from 53.4 to 77.1%. In conclusion, the inclusion IFA with C. pneumoniae-infected cells was best suited as a sensitive screening test for identifying specimens with elevated MIF titers (those associated with a possible acute infection with C. pneumoniae).

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Oscherwitz, Jon, Fen Yu et Kemp B. Cease. « A Heterologous Helper T-Cell Epitope Enhances the Immunogenicity of a Multiple-Antigenic-Peptide Vaccine Targeting the Cryptic Loop-Neutralizing Determinant of Bacillus anthracis Protective Antigen ». Infection and Immunity 77, n^o 12 (5 octobre 2009) : 5509–18. http://dx.doi.org/10.1128/iai.00899-09.

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ABSTRACT We previously showed that a multiple antigenic peptide (MAP) displaying amino acids (aa) 305 to 319 from the 2β2-2β3 loop of protective antigen (PA) can elicit high-titered antibody that neutralizes lethal toxin (LeTx) in vitro and that this loop-neutralizing determinant (LND) specificity is absent in PA-immune rabbits. Some immune rabbits were, however, nonresponders to the MAP. We hypothesized that the immunogen elicited suboptimal major histocompatibility complex (MHC) class II-restricted T-cell help and that introduction of a functional helper T-cell epitope would increase MHC-restricted responsiveness and the magnitude and affinity of the antibody responses. In the current study, we characterized the T- and B-cell responses to LND peptides in mice, then designed second-generation MAP immunogens for eliciting LND-specific immunity, and tested them in rabbits. The 305-319 sequence was devoid of helper T-cell epitopes in three strains of mice; however, a T-B peptide comprising aa 305 to 319, colinearly synthesized with the P30 helper epitope of tetanus toxin, elicited robust LeTx-neutralizing immunity in mice. T-B MAPs displaying B-cell epitopes 304 to 319 (MAP304) or 305 to 319 (MAP305) elicited high-titer, durable antibody responses in rabbits which exhibited potent neutralization of LeTx in vitro. All MAP304-immune rabbits demonstrated neutralization titers exceeding that of hyperimmune sera of rabbits immunized with PA in Freund's adjuvant, with peak neutralization titers 23-, 6-, and 3-fold higher than that of the PA antiserum. Overall, immunization with MAPs containing the P30 epitope elicited higher antibody and toxin neutralization titers and peptide-specific affinity than immunization with an LND MAP lacking a helper epitope. P30-containing MAP304 represents a promising LND-specific vaccine for anthrax.

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Bash, Margaret C., Freyja Lynn, Brian Mocca, Ray Borrow, Helen Findlow, Musa Hassan-King, Marie-Pierre Preziosi et al. « Development and Use of a Serum Bactericidal Assay Using Pooled Human Complement To Assess Responses to a Meningococcal Group A Conjugate Vaccine in African Toddlers ». Clinical and Vaccine Immunology 21, n^o 5 (26 mars 2014) : 755–61. http://dx.doi.org/10.1128/cvi.00812-13.

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ABSTRACTA meningococcal group A polysaccharide (PS) conjugate vaccine (PsA-TT) has been developed for African countries affected by epidemic meningitis caused byNeisseria meningitidis. Complement-mediated serum bactericidal antibody (SBA) assays are used to assess protective immune responses to meningococcal vaccination. Human complement (hC′) was used in early studies demonstrating antibody-mediated protection against disease, but it is difficult to obtain and standardize. We developed and evaluated a method for sourcing hC′ and then used the SBA assay with hC′ (hSBA) to measure bactericidal responses to PsA-TT vaccination in 12- to 23-month-old African children. Sera with active complement from 100 unvaccinated blood donors were tested for intrinsic bactericidal activity, SBA titer using rabbit complement (rSBA), and anti-group A PS antibody concentration. Performance criteria and pooling strategies were examined and then verified by comparisons of three independently prepared hC′ lots in two laboratories. hSBA titers of clinical trial sera were then determined using this complement sourcing method. Two different functional antibody tests were necessary for screening hC′. hSBA titers determined using three independent lots of pooled hC′ were within expected assay variation among lots and between laboratories. In African toddlers, PsA-TT elicited higher hSBA titers than meningococcal polysaccharide or Hib vaccines. PsA-TT immunization or PS challenge of PsA-TT-primed subjects resulted in vigorous hSBA memory responses, and titers persisted in boosted groups for over a year. Quantifying SBA using pooled hC′ is feasible and showed that PsA-TT was highly immunogenic in African toddlers.

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Borrelli, Silvia, Rehana B. Hossany et B. Mario Pinto. « Immunological Evidence for Functional Rather than Structural Mimicry by a Shigella flexneri Y Polysaccharide-Mimetic Peptide ». Clinical and Vaccine Immunology 15, n^o 7 (7 mai 2008) : 1106–14. http://dx.doi.org/10.1128/cvi.00050-08.

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ABSTRACT An approach to vaccine design is the use of molecules that mimic the immunogenic element of interest. In this context, the interaction of MDWNMHAA, a peptide mimic of the Shigella flexneri Y O polysaccharide (PS), with an anti-carbohydrate monoclonal antibody, as studied previously by X-ray crystallography, suggested the presence of functional rather than structural mimicry and a bound peptide conformation that was not represented significantly in the free-ligand ensemble. The antibody response elicited by an MDWNMHAA-carrier protein (tetanus toxoid [TT]) conjugate has now been investigated in BALB/c mice. The mice were immunized following a homologous prime/boost strategy using MDWNMHAA-TT as the immunogen. The mice showed anti-peptide antibody (immunoglobulin G [IgG]) titers that increased after being boosted. High anti-lipopolysaccharide (LPS) (IgG) titers were observed after the last boost. A faster immune response, with cross-reactive titers, was observed with a peptide conjugate with 30% more copies of the peptide. The binding of anti-peptide polyclonal antibodies to LPS could be inhibited by LPS, PS, MDWNMHAA, and MDWNMHAA-bovine serum albumin, as assessed by inhibition enzyme-linked immunosorbent assay. Conversely, mice immunized with PS-TT showed IgG anti-peptide titers. These data demonstrate the cross-reactivity of the antibody response and support the hypothesis that functional, as opposed to structural, mimicry of the S. flexneri Y O PS by MDWNMHAA or the underrepresentation of the bound ligand conformation in the free-ligand ensemble does not compromise immunological cross-reactivity. Prime/boost strategies were performed with a heterologous boost of PS-TT or MDWNMHAA-TT. They led to high anti-LPS titers after only three injections, suggesting alternatives to improve the immunogenicity of the carbohydrate-mimetic peptide and confirming the antigenic mimicry.

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Gruenglas, Jeffrey, James Mond, Micaela Scobie, Cynthia Tolman et Joseph Martinez. « 10. Kinetics of Post-Vaccination Seroprotection to S. Pneumonia for the Immune-Compromised and Vaccine-Naïve Populations ». Open Forum Infectious Diseases 7, Supplement_1 (1 octobre 2020) : S27—S28. http://dx.doi.org/10.1093/ofid/ofaa439.055.

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Abstract Background S. pneumonia infection presents a significant challenge, accounting for 20–38% of hospital-acquired pneumonia, and the leading cause of community-acquired pneumonia despite availability of effective vaccines. Incidence is highest in children under 2 years, the immunocompromised, and elderly. CDC has reported the emergence of antibiotic resistance in ~30% of cases, adding to risk of morbidity and mortality. Fewer than half of the elderly are vaccinated and vulnerable to infection on admission. Passive immunotherapy as an adjunct to vaccines may improve outcomes in such populations. The objective of this study was to evaluate whether seroprotective response induced with a pneumococcal conjugate vaccine could rapidly yield protective opsonic levels of antibody within anticipated duration of hospitalization. Methods Healthy donors (n=30) were immunized with Prevnar. Blood was drawn on days 0, 3, 7, 10, 14, 21, and 28. Samples were pooled and tested for presence of functional opsonic antibodies recognizing capsular polysaccharides. Clearance mechanism of S. pneumonia was based on antibody recognition to pneumococcal capsular polysaccharide and opsonic titers used as an in vitro surrogate to evaluate the efficacy of vaccine. Results There was little to no opsonic activity against most serotypes on day 0, except for low antibody activity with serotypes 1, 3, 4, and 5. Titers increased, with protective levels achieved by day 10 for most serotypes (except 14 and 18C), peaking at day 14 or after across serotypes (Figures 1 and 2). Average titers rose from log2 titer 2 on day 0 to log2 titer 8 on days 21 and 28. Titers against most serotypes reached log2 10 (titer 1024) or higher. Patients remained susceptible to nosocomial infection for at least 10 days post admission until protective titers are reached. OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V. N=2. OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 14, 18C, 19A, 19F, and 23F. N=2. Conclusion Patients with no prior history of vaccination (or inability to mount response) with Prevnar or pneumovax remain vulnerable to S. pneumonia infection even if vaccinated on entry, due to delayed kinetics in reaching protective titers. These patients may require prophylactic intervention of hyperimmune Ig with high opsonic titers to S. pneumonia, providing protection until vaccine response elicits protective antibodies. Disclosures All Authors: No reported disclosures

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Martinez, Joseph, Tamara Pilishvili, Suzanne Barnard, Joseph Caba, Willie Spear, Sandra Romero-Steiner et George M. Carlone. « Opsonophagocytosis of Fluorescent Polystyrene Beads Coupled to Neisseria meningitidis Serogroup A, C, Y, or W135 Polysaccharide Correlates with Serum Bactericidal Activity ». Clinical and Vaccine Immunology 9, n^o 2 (mars 2002) : 485–88. http://dx.doi.org/10.1128/cdli.9.2.485-488.2002.

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ABSTRACT We developed a polysaccharide-specific flow cytometric opsonophagocytic assay (OPA) for the simultaneous measurement of functional antibody to Neisseria meningitidis serogroups A, C, Y, and W135. OPA titers significantly correlated with serum bactericidal assay titers for all serogroups tested (mean r = 0.96; P < 0.001). OPA could be used in meningococcal vaccine evaluation.

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Balingit, Jean Claude, Minh Huong Phu Ly, Mami Matsuda, Ryosuke Suzuki, Futoshi Hasebe, Kouichi Morita et Meng Ling Moi. « A Simple and High-Throughput ELISA-Based Neutralization Assay for the Determination of Anti-Flavivirus Neutralizing Antibodies ». Vaccines 8, n^o 2 (10 juin 2020) : 297. http://dx.doi.org/10.3390/vaccines8020297.

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Mosquito-borne flavivirus infections, including dengue virus and Zika virus, are major public health threats globally. While the plaque reduction neutralization test (PRNT) is considered the gold standard for determining neutralizing antibody levels to flaviviruses, the assay is time-consuming and laborious. This study, therefore, aimed to develop an enzyme-linked immunosorbent assay (ELISA)-based microneutralization test (EMNT) for the detection of neutralizing antibodies to mosquito-borne flaviviruses. The inhibition of viral growth due to neutralizing antibodies was determined colorimetrically by using EMNT. Given the significance of Fcγ-receptors (FcγR) in antibody-mediated neutralization and antibody-dependent enhancement (ADE) of flavivirus infection, non-FcγR and FcγR-expressing cell lines were used in the EMNT to allow the detection of the sum of neutralizing and immune-enhancing antibody activity as the neutralizing titer. Using anti-flavivirus monoclonal antibodies and clinical samples, the utility of EMNT was evaluated by comparing the end-point titers of the EMNT and the PRNT. The correlation between EMNT and PRNT titers was strong, indicating that EMNT was robust and reproducible. The new EMNT assay combines the biological functional assessment of virus neutralization activity and the technical advantages of ELISA and, is simple, reliable, practical, and could be automated for high-throughput implementation in flavivirus surveillance studies and vaccine trials.

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Miura, Kazutoyo, Mahamadou Diakite, Samuel Moretz, Hong Zhou, Ababacar Diouf, Gregory Tullo, Tatiana Lopera-Mesal, Jennifer Anderson, Rick Fairhurst et Carole Long. « Impact of sickle-cell trait on humoral immunity against Plasmodium falciparum in children living in malaria endemic areas of Mali (45.10) ». Journal of Immunology 184, n^o 1_Supplement (1 avril 2010) : 45.10. http://dx.doi.org/10.4049/jimmunol.184.supp.45.10.

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Abstract Previous studies have shown that children with sickle-cell trait (heterozygosity for normal hemoglobin A and sickle hemoglobin S, genotype AS) are resistant to P. falciparum malaria when compared with AA children. Passive transfer studies have established the importance of antibodies against blood-stage parasites. However, the impact of sickle-cell trait on immunity against parasite antigens has not been extensively studied. In a longitudinal study in rural Mali, we followed 73 AS and 126 AA children for an entire 6-month transmission season. Before the transmission season, antibody titers were measured against 4 parasite blood-stage antigens (AMA1, MSP1, EBA175 and MSP2). AS children experienced significantly fewer malaria episodes than AA children. Because there is a significant effect of age on antibody titers, we stratified children in 3 age groups (3-5, 6-8 and 9-11 years). Compared to AA children aged 9-11 years, AS children showed significantly lower antibody titers to all 4 antigens. For the 6-8 years group, AS children showed significantly lower antibody titers to EBA175 and MSP2. No differences were observed between AA and AS children 3-5 years old for any antigen. These data suggest that the antibody titers against these major blood-stage antigens before transmission season are not involved in reducing the incidence of malaria in AS children. The functional activity of antibodies (i.e., in vitro parasite growth-inhibitory activity) will be also presented.

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Kobold, Sebastian, Yanran Cao, Sinje Tams, Britta Marlen Bartels, Tim Lütkens, Caroline Pabst, Andreas Marx et al. « Longitudinal and Functional Analysis of Spontaneous NY-ESO-1-Specific Antibody Responses in Multiple Myeloma Patients. » Blood 114, n^o 22 (20 novembre 2009) : 2831. http://dx.doi.org/10.1182/blood.v114.22.2831.2831.

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Abstract Abstract 2831 Poster Board II-807 Its tumor-restricted expression and its high immunogenicity render cancer-testis (CT) antigen NY-ESO-1 an exquisite target for antigen-specific immunotherapies. Spontaneous antibody responses against NY-ESO-1 are typically found in a subset of patients with solid tumors. However, little is known regarding serological immune responses against NY-ESO-1 in patients with hematological malignancies including multiple myeloma (MM). Furthermore, no consequent longitudinal analyses have been performed correlating NY-ESO-1-specific antibody titers with the clinical development of the given malignancy. Finally, nothing is known regarding the functional capabilities of spontaneously occurring anti-NY-ESO-1 antibodies in MM or other malignancies. Here, we performed the first longitudinal and functional investigation of NY-ESO-1-specific antibody responses in MM analyzing 1100 sera and 200 bone marrow plasma samples of 194 MM patients. Sera and BM plasma samples of 100 healthy donors served as controls. Screening sera and bone marrow plasma of our MM patients by Enzyme-linked Immunosorbent Assay (ELISA) using full length recombinant NY-ESO-1 protein, we found that 5/194 patients had high-titered antibody responses against this CT antigen. A quantitative B cell ELISPOT demonstrated NY-ESO-1-specific B cells in the peripheral blood as well as in the bone marrow of the respective MM patients. In a western blot analysis, spontaneous NY-ESO-1-specific immune responses in the patients were found to be highly specific for both native and recombinant protein. Epitope mapping in an ELISA using 18 overlapping NY-ESO-1 20mer peptides showed that antibody responses were restricted to the first 70 amino acids of the full-length protein. NY-ESO-1-specific antibodies consisted mainly of IgG1 and to a lower extent of IgG3 subtypes. No IgG2, IgG4, IgM or IgA antibodies against NY-ESO-1 were detected. Interestingly, antibody affinity increased over the course of the disease suggesting an affinity driven antibody maturation. Accordingly, NY-ESO-1-specific antibodies of MM patients were found to be potent complement activators in a western blot technique. On the other hand, despite the high functional capabilities of NY-ESO-1-specific antibodies, antibody titers increased with each NY-ESO-1-expressing (as indicated by reverse-transcriptase-polymerase-chain-reaction and immunohistochemistry) recurrence of the disease. In conclusion, we demonstrate here the spontaneous occurrence of high-titered NY-ESO-1-specific antibodies in MM patients. One reason for the relatively low frequency of antibody responses against NY-ESO-1 might be that most patients were in early stages of the disease or in remission at the time the analysis was performed. Antibodies were produced by NY-ESO-1-specific B cells detectable in the bone marrow as well as in the peripheral blood of the patients. NY-ESO-1-specific antibodies were evoked by a distinct and immunodominant fragment of NY-ESO-1. Affinity maturation of this response and complement activation by the spontaneously occurring NY-ESO-1-specific IgG1-type antibodies speak in favour of an effective serological immune response. However, positive correlation of antibody titers with tumor burden and recurrence of the disease suggest an inability of antibodies targeting intracellular protein NY-ESO-1 to control the course of the disease, at least in the long run. Antigen-specific immunotherapy might be necessary to shape NY-ESO-1-specific immunity in MM patients and, particularly, to mobilize tumor-specific T cell responses. Disclosures: No relevant conflicts of interest to declare.

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Kim, H.-J., Y.-H. Hong, Y.-J. Kim, H.-S. Kim, J.-W. Park, J.-Y. Do, K.-J. Kim, S.-W. Bae, C.-W. Kim et C.-K. Lee. « Anti-heparan sulfate antibody and functional loss of glomerular heparan sulfate proteoglycans in lupus nephritis ». Lupus 26, n^o 8 (21 décembre 2016) : 815–24. http://dx.doi.org/10.1177/0961203316678674.

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Background The purpose of this study was to evaluate the features of heparan sulfate proteoglycans (HSPGs) as agrins of the glomerular basement membrane (GBM) and circulating anti–heparan sulfate (HS) antibodies in lupus nephritis, comparing titers among the following groups: lupus nephritis (LN), non-renal lupus, non-lupus nephritis, and healthy controls. Methods The stage of nephritis was determined based on the kidney biopsy. Alcian blue staining and immunohistochemical (IHC) staining for agrin were performed for histological evaluation of GBM HSPGs in normal glomeruli, non-lupus membranous glomerulonephritis (MGN), and lupus MGN. The results were used for measurement of the serum anti-HS antibody titers using an enzyme-linked immunosorbent assay (ELISA) in the following groups: 38 healthy controls, 38 non-lupus nephritis, 37 non-renal lupus, and 38 LN. Results Glomerulus HSPGs were stained bluish-green along the GBM with Alcian blue. However, IHC staining against agrin was almost completely negative in the lupus MGN group compared with the normal and non-lupus MGN groups, which showed brown staining of GBM. A higher level of anti-HS IgG was detected in LN compared with other groups, respectively. Higher titers were associated with the presence of SLE and nephritis. A higher degree of proteinuria normalized to glomerular filtration rate (eGFR) was observed in association with higher anti-HS antibody titers in LN. Conclusion This study demonstrated a functional loss of GBM HSPGs and higher levels of circulating anti-HS antibodies as a characteristic feature of lupus nephritis, suggesting their involvement in the pathogenesis of lupus nephritis and proteinuria.

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Thomsen, Isaac P., Ashley L. DuMont, David B. A. James, Pauline Yoong, Benjamin R. Saville, Nicole Soper, Victor J. Torres et C. Buddy Creech. « Children with Invasive Staphylococcus aureus Disease Exhibit a Potently Neutralizing Antibody Response to the Cytotoxin LukAB ». Infection and Immunity 82, n^o 3 (30 décembre 2013) : 1234–42. http://dx.doi.org/10.1128/iai.01558-13.

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ABSTRACTDespite the importance ofStaphylococcus aureusas a common invasive bacterial pathogen, the humoral response to infection remains inadequately defined, particularly in children. The purpose of this study was to assess the humoral response to extracellular staphylococcal virulence factors, including the bicomponent leukotoxins, which are critical for the cytotoxicity ofS. aureustoward human neutrophils. Children with culture-provenS. aureusinfection were prospectively enrolled and stratified by disease type. Fifty-three children were enrolled in the study, of which 90% had invasive disease. Serum samples were obtained during the acute (within 48 h) and convalescent (4 to 6 weeks postinfection) phases, at which point both IgG titers againstS. aureusexotoxins were determined, and the functionality of the generated antibodies was evaluated. Molecular characterization of clinical isolates was also performed. We observed a marked rise in antibody titer from acute-phase to convalescent-phase sera for LukAB, the most recently describedS. aureusbicomponent leukotoxin. LukAB production by the isolates was strongly correlated with cytotoxicityin vitro, and sera containing anti-LukAB antibodies potently neutralized cytotoxicity. Antibodies toS. aureusantigens were detectable in healthy pediatric controls but at much lower titers than in sera from infected subjects. The discovery of a high-titer, neutralizing antibody response to LukAB during invasive infections suggests that this toxin is producedin vivoand that it elicits a functional humoral response.

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Granoff, Dan M., Susan E. Maslanka, George M. Carlone, Brian D. Plikaytis, George F. Santos, Ahmad Mokatrin et Howard V. Raff. « A Modified Enzyme-Linked Immunosorbent Assay for Measurement of Antibody Responses to Meningococcal C Polysaccharide That Correlate with Bactericidal Responses ». Clinical Diagnostic Laboratory Immunology 5, n^o 4 (1 juillet 1998) : 479–85. http://dx.doi.org/10.1128/cdli.5.4.479-485.1998.

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ABSTRACT The standardized enzyme-linked immunosorbent assay (ELISA) for measurement of serum immunoglobulin G (IgG) antibody responses to meningococcal C polysaccharide has been modified to employ assay conditions that ensure specificity and favor detection primarily of high-avidity antibodies. The modified and standard assays were used to measure IgG antibody concentrations in sera of toddlers vaccinated with meningococcal polysaccharide vaccine or a meningococcal C conjugate vaccine. The results were compared to the respective complement-mediated bactericidal antibody titers. In sera obtained after one or two doses of vaccine, the correlation coefficients, r, for the results of the standard assay and bactericidal antibody titers were 0.45 and 0.29, compared to 0.85 and 0.87, respectively, for the modified assay. With the standard assay, there were no significant differences between the geometric mean antibody responses of the two vaccine groups. In contrast, with the modified assay, 5- to 20-fold higher postvaccination antibody concentrations were measured in the conjugate than in the polysaccharide group. Importantly, the results of the modified assay, but not the standard ELISA, paralleled the respective geometric mean bactericidal antibody titers. Thus, by employing conditions that favor detection of higher-avidity IgG antibody, the modified ELISA provides results that correlate closely with measurements of antibody functional activity that are thought to be important in protection against meningococcal disease.

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Kozel, Thomas R., Randall S. MacGill, Ann Percival et Qing Zhou. « Biological Activities of Naturally Occurring Antibodies Reactive with Candida albicans Mannan ». Infection and Immunity 72, n^o 1 (janvier 2004) : 209–18. http://dx.doi.org/10.1128/iai.72.1.209-218.2004.

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ABSTRACT Sera from normal adult humans may contain high levels of antibody reactive with Candida albicans mannan. This study examined selected biological activities of such antibodies, focusing on sera that were collected from 34 donors and analyzed individually. The results showed that antimannan titers were normally distributed. Reactivity as determined by enzyme-linked immunosorbent assay with serotype A mannan generally paralleled reactivity with serotype B. Analysis of the kinetics for activation of the complement system and deposition of complement component 3 (C3) onto serotype A and serotype B cells showed a decrease in the lag time that occurred before the onset of rapid accumulation of C3 that correlated with increasing antimannan titers. In contrast, there was a decrease in the overall rate of accumulation of C3 on serotype A cells that was strongly correlated with increasing antibody titers; serotype B cells showed no such decrease. An evaluation of the contribution of mannan antibody to opsonophagocytic killing showed that mannan antibody in individual sera and antimannan immunoglobulin G (IgG) affinity purified from human plasma contributed to killing by neutrophils in a dose-dependent fashion in the absence of a functional complement system. However, affinity-purified antibody in very high concentrations was inhibitory to both complement-dependent and complement-independent opsonophagocytosis, and this finding suggests a prozone-like effect. In contrast, if the complement system was functional, antimannan IgG was not needed for opsonophagocytic killing. These results suggest that naturally occurring mannan antibodies and the complement system are functionally redundant for opsonophagocytic killing by neutrophils.

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Sterz, R. K., G. Biro, K. Rajki, G. Filipp et K. Peper. « Experimental autoimmune myasthenia gravis : can pretreatment with 125I-labeled receptor prevent functional damage at the neuromuscular junction ? » Journal of Immunology 134, n^o 2 (1 février 1985) : 841–46. http://dx.doi.org/10.4049/jimmunol.134.2.841.

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Abstract Rats were immunized with purified receptor from electric fish to induce experimental autoimmune myasthenia gravis (EAMG). It is implied by the clonal selection theory that antigens react only with receptors on specific immunocompetent cell subpopulations. In an attempt to damage these specific cells with the aid of highly radioactive antigen, one group of rats was pretreated with an additional injection of radiolabeled receptor of high specific activity 3 days before the basic immunization. The success of the immunization was monitored by measuring changes in the following three parameters: antibody titers against nicotinic acetylcholine receptor; number of alpha-bungarotoxin-binding sites at endplates; and number of acetylcholine-operated ionic endplate channels, using quantitative electrophysiologic methods. Conventionally immunized animals showed the classical signs of EAMG: elevated antibody titers against nicotinic acetylcholine receptor and a reduction of the number of alpha-bungarotoxin-binding sites, as well as reduction of the number of acetylcholine-operated ionic channels. The same symptoms were found in animals pretreated with unlabeled receptor and in animals pretreated with radioactive albumin. Animals pretreated with radioactively labeled receptor showed far less reduction of functional nicotinic acetylcholine receptor and only slightly raised antibody titers. This study suggests that preimmunization with radioactive antigen selectively eliminates immunocompetent cells, thus precluding the production of antibodies by a subsequent immunization procedure. The same protective effect cannot be obtained by either preimmunization with unlabeled antigen or by radioactively labeled unspecific antigen.

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Maciejewski, Sonia, Tracy J. Ruckwardt, Kaitlyn M. Morabito, Bryant M. Foreman, Katherine E. Burgomaster, David N. Gordon, Rebecca S. Pelc et al. « Distinct neutralizing antibody correlates of protection among related Zika virus vaccines identify a role for antibody quality ». Science Translational Medicine 12, n^o 547 (10 juin 2020) : eaaw9066. http://dx.doi.org/10.1126/scitranslmed.aaw9066.

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The emergence of Zika virus (ZIKV) in the Americas stimulated the development of multiple ZIKV vaccine candidates. We previously developed two related DNA vaccine candidates encoding ZIKV structural proteins that were immunogenic in animal models and humans. We sought to identify neutralizing antibody (NAb) properties induced by each vaccine that correlated with protection in nonhuman primates (NHPs). Despite eliciting equivalent NAb titers in NHPs, these vaccines were not equally protective. The transfer of equivalent titers of vaccine-elicited NAb into AG129 mice also revealed nonequivalent protection, indicating qualitative differences among antibodies (Abs) elicited by these vaccines. Both vaccines elicited Abs with similar binding titers against envelope protein monomers and those incorporated into virus-like particles, as well as a comparable capacity to orchestrate phagocytosis. Functional analysis of vaccine-elicited NAbs from NHPs and humans revealed a capacity to neutralize the structurally mature form of the ZIKV virion that varied in magnitude among vaccine candidates. Conversely, sensitivity to the virion maturation state was not a characteristic of NAbs induced by natural or experimental infection. Passive transfer experiments in mice revealed that neutralization of mature ZIKV virions more accurately predicts protection from ZIKV infection. These findings demonstrate that NAb correlates of protection may differ among vaccine antigens when assayed using standard neutralization platforms and suggest that measurements of Ab quality, including the capacity to neutralize mature virions, will be critical for defining correlates of ZIKV vaccine-induced immunity.

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Findlow, Jamie, Ann Holland, Diana Martin, Philipp Oster, Paul Balmer et Ray Borrow. « Inadequacy of Colominic Acid as an Absorbent Intended To Facilitate Use of Complement-Preserved Baby Rabbit Serum in the Neisseria meningitidis Serogroup B Serum Bactericidal Antibody Assay ». Clinical and Vaccine Immunology 14, n^o 5 (7 mars 2007) : 556–61. http://dx.doi.org/10.1128/cvi.00452-06.

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ABSTRACT The surrogate of protection against Neisseria meningitidis serogroup B (MenB) is the serum bactericidal antibody (SBA) assay, which measures the functional activity of antibody by using an exogenous complement source. Despite baby rabbit complement having been used in meningococcal serogroup A, C, Y, and W135 SBA assays, it is not recommended for use in the MenB SBA assay due to elevated SBA titers caused by low-avidity anti-MenB capsular antibody in test sera. Therefore, the possibility of absorbing anti-MenB capsular antibody from test sera to enable the use of baby rabbit complement in the MenB SBA assay was investigated by comparing the results with those gained using human complement. Colominic acid from Escherichia coli K1, which shares the same linkage residue as MenB polysaccharide, was used as an absorbent due to the commercial unavailability of purified MenB polysaccharide. Inclusion of soluble colominic acid as an absorbent with baby rabbit complement resulted in a general reduction in SBA titers compared with those obtained using baby rabbit complement alone. However, these were not comparable to human SBA titers for all samples. Further optimization and investigations demonstrated that for some samples, colominic acid reduced titers to less than those achieved with human complement, and for others, it was not possible to inhibit titers by using colominic acid. The results suggested that the use of colominic acid will not result in the ability to use baby rabbit complement in the MenB SBA assay, thus not alleviating the difficulties in procuring human complement. However, alternative absorbents, such as purified MenB polysaccharide, may warrant further evaluation.

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Sato, Mizuho, Reiko Saito, Naohito Tanabe, Makoto Nishikawa, Asami Sasaki, Fumitake Gejyo et Hiroshi Suzuki. « Antibody Response to Influenza Vaccination in Nursing Home Residents and Healthcare Workers During Four Successive Seasons in Niigata, Japan ». Infection Control & ; Hospital Epidemiology 26, n^o 11 (novembre 2005) : 859–66. http://dx.doi.org/10.1086/502509.

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AbstractObjective:To evaluate the antibody response to influenza vaccines in nursing home residents and healthcare workers (HCWs) and its relation to residents' functional and chronic disease status during four successive seasons.Design:Before-after study.Setting:Nine nursing homes during the 1998-1999 season and two during the 1999-2000, 2000-2001, and 2001-2002 seasons.Participants:Two hundred fifty-nine residents and 79 HCWs during the 1998-1999 season; 180 and 71, respectively, during the 1999-2000 season; 162 and 71, respectively, during the 2000-2001 season; and 153 and 79, respectively, during the 2001-2002 season.Results:Multivariate analysis indicated that the mean fold increase in the geometric mean titers (GMTs) of hemagglutination inhibition (HI) antibodies and the response rate (the proportion of vaccinées resulting in a significant, at least fourfold increase in antibody titer) were good and no significant differences occurred for almost all strains in both residents and HCWs. The GMTs of HI antibodies and the protection rate (the proportion of participants with HI antibody titers & 40) were increased in both residents and HCWs, but were significantly lower for almost all strains in residents than in HCWs. Furthermore, multivariate analysis indicated that subdivision of residents into three groups by level of daily activities and into four groups according to underlying diseases revealed only minor differences in immune responses.Conclusions:Antibody responses to the influenza vaccine were lower in residents than in HCWs. However, residents showed similar antibody responses regardless of their level of daily activity or underlying diseases.

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Fendler, Annika, Lewis Au, Scott T. C. Shepherd, Fiona Byrne, Maddalena Cerrone, Laura Amanda Boos, Karolina Rzeniewicz et al. « Functional antibody and T cell immunity following SARS-CoV-2 infection, including by variants of concern, in patients with cancer : the CAPTURE study ». Nature Cancer 2, n^o 12 (27 octobre 2021) : 1321–37. http://dx.doi.org/10.1038/s43018-021-00275-9.

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AbstractPatients with cancer have higher COVID-19 morbidity and mortality. Here we present the prospective CAPTURE study, integrating longitudinal immune profiling with clinical annotation. Of 357 patients with cancer, 118 were SARS-CoV-2 positive, 94 were symptomatic and 2 died of COVID-19. In this cohort, 83% patients had S1-reactive antibodies and 82% had neutralizing antibodies against wild type SARS-CoV-2, whereas neutralizing antibody titers against the Alpha, Beta and Delta variants were substantially reduced. S1-reactive antibody levels decreased in 13% of patients, whereas neutralizing antibody titers remained stable for up to 329 days. Patients also had detectable SARS-CoV-2-specific T cells and CD4+ responses correlating with S1-reactive antibody levels, although patients with hematological malignancies had impaired immune responses that were disease and treatment specific, but presented compensatory cellular responses, further supported by clinical recovery in all but one patient. Overall, these findings advance the understanding of the nature and duration of the immune response to SARS-CoV-2 in patients with cancer.

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Sariol, Carlos, Petraleigh Pantoja, Crisanta Serrano-Collazo, Tiffany Rosa-Arocho, Albersy Armina-Rodríguez, Lorna Cruz, E. Stone et al. « Function Is More Reliable than Quantity to Follow Up the Humoral Response to the Receptor-Binding Domain of SARS-CoV-2-Spike Protein after Natural Infection or COVID-19 Vaccination ». Viruses 13, n^o 10 (30 septembre 2021) : 1972. http://dx.doi.org/10.3390/v13101972.

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Both the SARS-CoV-2 pandemic and emergence of variants of concern have highlighted the need for functional antibody assays to monitor the humoral response over time. Antibodies directed against the spike (S) protein of SARS-CoV-2 are an important component of the neutralizing antibody response. In this work, we report that in a subset of patients—despite a decline in total S-specific antibodies—neutralizing antibody titers remain at a similar level for an average of 98 days in longitudinal sampling of a cohort of 59 Hispanic/Latino patients exposed to SARS-CoV-2. Our data suggest that 100% of seroconverting patients make detectable neutralizing antibody responses which can be quantified by a surrogate viral neutralization test. Examination of sera from ten out of the 59 subjects which received mRNA-based vaccination revealed that both IgG titers and neutralizing activity of sera were higher after vaccination compared to a cohort of 21 SARS-CoV-2 naïve subjects. One dose was sufficient for the induction of a neutralizing antibody, but two doses were necessary to reach 100% surrogate virus neutralization in subjects irrespective of previous SARS-CoV-2 natural infection status. Like the pattern observed after natural infection, the total anti-S antibodies titers declined after the second vaccine dose; however, neutralizing activity remained relatively constant for more than 80 days after the first vaccine dose. Furthermore, our data indicates that—compared with mRNA vaccination—natural infection induces a more robust humoral immune response in unexposed subjects. This work is an important contribution to understanding the natural immune response to the novel coronavirus in a population severely impacted by SARS-CoV-2. Furthermore, by comparing the dynamics of the immune response after the natural infection vs. the vaccination, these findings suggest that functional neutralizing antibody tests are more relevant indicators than the presence or absence of binding antibodies.

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Xu, Qingfu, et Mingtao Zeng. « Detoxified Lethal Toxin as a Potential Mucosal Vaccine against Anthrax ». Clinical and Vaccine Immunology 15, n^o 4 (6 février 2008) : 612–16. http://dx.doi.org/10.1128/cvi.00402-07.

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ABSTRACT The nontoxic mutant lethal factor (mLF; which has the E687C substitution) and functional protective antigen (PA63) of Bacillus anthracis were evaluated for their use as mucosal vaccines against anthrax in A/J mice. Intranasal vaccination of three doses of 30 μg of mLF or 60 μg of PA63 elicited significant serum and mucosal antibody responses, with anthrax lethal toxin-neutralizing titers of 40 and 60 in immune sera, respectively. However, only 30% and 60% of the vaccinated animals in the two groups could survive a challenge with 100 times the 50% lethal dose of B. anthracis Sterne spores, respectively. In contrast, vaccination with three doses of the combination of 30 μg of mLF and 60 μg of PA63, the detoxified lethal toxin, elicited antibody responses against LF and PA significantly higher than those elicited after vaccination with mLF or PA63 individually by use of the same dose and schedule. Vaccination with the detoxified lethal toxin resulted in significantly higher lethal toxin-neutralizing antibody titers in sera (titer, 90). Animals vaccinated with three doses of the detoxified lethal toxin were completely protected against the spore challenge. The data suggest that mLF and PA63 have a mutual enhancement effect for evoking systemic and mucosal immune responses and that the detoxified lethal toxin can be used as an efficient mucosal vaccine against anthrax.

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Mathews, Christine E., Eric L. Brown, Perla J. Martinez, Upasana Bagaria, Moon H. Nahm, Robert L. Burton, Susan P. Fisher-Hoch, Joseph B. McCormick et Shaper Mirza. « Impaired Function of Antibodies to Pneumococcal Surface Protein A but Not to Capsular Polysaccharide in Mexican American Adults with Type 2 Diabetes Mellitus ». Clinical and Vaccine Immunology 19, n^o 9 (3 juillet 2012) : 1360–69. http://dx.doi.org/10.1128/cvi.00268-12.

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ABSTRACTThe goal of the study was to determine baseline protective titers of antibodies toStreptococcus pneumoniaesurface protein A (PspA) and capsular polysaccharide in individuals with and individuals without type 2 diabetes mellitus. A total of 561 individuals (131 individuals with diabetes and 491 without) were screened for antibodies to PspA using a standard enzyme-linked immunosorbent assay (ELISA). A subset of participants with antibodies to PspA were retested using a WHO ELISA to determine titers of antibodies to capsular polysaccharide (CPS) (serotypes 4, 6B, 9V, 14, 18C, 19A, 19F, and 23F). Functional activity of antibodies was measured by assessing their ability to enhance complement (C3) deposition on pneumococci and promote killing of opsonized pneumococci. Titers of antibodies to protein antigens (PspA) were significantly lower in individuals with diabetes than controls without diabetes (P= 0.01), and antibodies showed a significantly reduced complement deposition ability (P= 0.02). Both antibody titers and complement deposition were negatively associated with hyperglycemia. Conversely, titers of antibodies to capsular polysaccharides were either comparable between the two groups or were significantly higher in individuals with diabetes, as was observed for CPS 14 (P= 0.05). The plasma specimens from individuals with diabetes also demonstrated a higher opsonophagocytic index against CPS serotype 14. Although we demonstrate comparable protective titers of antibodies to CPS in individuals with and individuals without diabetes, those with diabetes had lower PspA titers and poor opsonic activity strongly associated with hyperglycemia. These results suggest a link between diabetes and impairment of antibody response.

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Martinez, Joseph E., Sandra Romero-Steiner, Tamara Pilishvili, Suzanne Barnard, Joseph Schinsky, David Goldblatt et George M. Carlone. « A Flow Cytometric Opsonophagocytic Assay for Measurement of Functional Antibodies Elicited after Vaccination with the 23-Valent Pneumococcal Polysaccharide Vaccine ». Clinical Diagnostic Laboratory Immunology 6, n^o 4 (1 juillet 1999) : 581–86. http://dx.doi.org/10.1128/cdli.6.4.581-586.1999.

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ABSTRACT Opsonophagocytosis is the primary mechanism for clearance of pneumococci from the host, and the measurement of opsonophagocytic antibodies appears to correlate with vaccine-induced protection. We developed a semiautomated flow cytometric opsonophagocytosis assay using HL-60 granulocytes as effector cells and nonviable 5,6-carboxyfluorescein, succinimidyl ester-labeled Streptococcus pneumoniae (serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F) as bacterial targets. The flow cytometric opsonophagocytosis assay was highly reproducible (for 87% of repetitive assays the titers were within 1 dilution of the median titer) and serotype specific, with ≥97% inhibition of opsonophagocytic titer by addition of homologous serotype-specific polysaccharide. In general, opsonophagocytic titers were not significantly inhibited by the presence of either heterologous pneumococcal polysaccharide or penicillin in the serum. The flow cytometric assay could reproducibly measure functional antibody activity in prevaccination (n = 28) and postvaccination (n = 36) serum specimens from healthy adult volunteers vaccinated with the 23-valent pneumococcal polysaccharide vaccine. When compared with a standardized manual viable opsonophagocytic assay, a high correlation (r = 0.89;P ≤ 0.01) was found between the two assays for the seven serotypes tested. The flow cytometric assay is rapid (∼4 h) with high throughput (∼50 serum samples per day per technician) and provides a reproducible measurement of serotype-specific functional antibodies, making it a highly suitable assay for the evaluation of the immune responses elicited by pneumococcal vaccines.

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Bogaert, Debby, Paul van der Valk, Reshmi Ramdin, Marcel Sluijter, Evelyn Monninkhof, Ron Hendrix, Ronald de Groot et Peter W. M. Hermans. « Host-Pathogen Interaction during Pneumococcal Infection in Patients with Chronic Obstructive Pulmonary Disease ». Infection and Immunity 72, n^o 2 (février 2004) : 818–23. http://dx.doi.org/10.1128/iai.72.2.818-823.2004.

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ABSTRACT Acute exacerbation is a frequent complication of chronic obstructive pulmonary disease (COPD). Recent studies suggested a role for bacteria such as Streptococcus pneumoniae in the development of acute exacerbation. For this study, we investigated the following in COPD patients: (i) the epidemiology of pneumococcal colonization and infection, (ii) the effect of pneumococcal colonization on the development of exacerbation, and (iii) the immunological response against S. pneumoniae. We cultured sputa of 269 COPD patients during a stable state and during exacerbation of COPD and characterized 115 pneumococcal isolates by use of serotyping. Moreover, we studied serum immunoglobulin G (IgG) antibody titers, antibody avidities, and functional antibody titers against the seven conjugate vaccine serotypes in these patients. Colonization with only pneumococci (monocultures) increased the risk of exacerbation, with a hazard ratio of 2.93 (95% confidence interval, 1.41 to 6.07). The most prevalent pneumococcal serotypes found were serotypes 19F, 3, 14, 9L/N/V, 23A/B, and 11. We calculated the theoretical coverage for the 7- and 11-valent pneumococcal vaccines to be 60 and 73%, respectively. All patients had detectable IgG levels against the seven conjugate vaccine serotypes. These antibody titers were significantly lower than those in vaccinated healthy adults. Finally, on average, a 2.5-fold rise in serotype-specific and functional antibodies in S. pneumoniae-positive sputum cultures was observed during exacerbation. Our data indicate that pneumococcal colonization in COPD patients is frequently caused by vaccine serotype strains. Moreover, pneumococcal colonization is a risk factor for exacerbation of COPD. Finally, our findings demonstrate that COPD patients are able to mount a significant immune response to pneumococcal infection. COPD patients may therefore benefit from pneumococcal vaccination.

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Leist, T. P., S. P. Cobbold, H. Waldmann, M. Aguet et R. M. Zinkernagel. « Functional analysis of T lymphocyte subsets in antiviral host defense. » Journal of Immunology 138, n^o 7 (1 avril 1987) : 2278–81. http://dx.doi.org/10.4049/jimmunol.138.7.2278.

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Abstract The role of different T cell subsets in antiviral host defense was investigated by treating thymectomized C57BL/6 and CBA/J mice with monoclonal rat anti-Lyt-2 or anti-L3/T4 IgG 2b antibodies 14 and 10 days before infection. This treatment depleted the respective T cell subsets to undetectable levels in peripheral blood when assayed by immunofluorescence. In mice treated with anti-Lyt-2, induction of cytotoxic T cells was reduced to less than 1 to 2% after intravenous infection with Armstrong strain of lymphocytic choriomeningitis virus (LCMV). In addition, no primary swelling of the footpad could be detected following local inoculation of the virus. In animals treated with anti-L3/T4, antiviral cytotoxic T lymphocyte responses were reduced by a factor of 10. These L3/T4+ cell-depleted mice showed delayed footpad swelling after local injection of LCMV Armstrong. After intracerebral infection with LCMV, anti-Lyt-2-treated mice were resistant and those injected with anti-L3/T4 were totally susceptible to LCMV Armstrong-triggered immunopathologic disease. Virus could be detected in the blood of antibody-treated mice 7 days after inoculation; however, no virus could be measured in the blood of surviving anti-Lyt-2-treated animals 15 days after intracerebral infection. Serum titers of interferon-alpha,beta induced by viral infection remained unaffected by depletion of T cell subsets. Anti-L3/T4 antibody-treated C57BL/6 mice failed to generate IgG antibodies against the New Jersey strain of vesicular stomatitis virus, whereas Lyt-2+ cell-depleted mice had normal antivesicular stomatitis virus (New Jersey strain) IgG antibody titers.

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Winter, Linda E., et Stephen J. Barenkamp. « HumanAntibodies Specific for the High-Molecular-Weight Adhesion Proteins ofNontypeable Haemophilus influenzae Mediate OpsonophagocyticActivity ». Infection and Immunity 71, n^o 12 (décembre 2003) : 6884–91. http://dx.doi.org/10.1128/iai.71.12.6884-6891.2003.

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ABSTRACT The HMW1- and HMW2-like adhesion proteins of nontypeable Haemophilus influenzae are expressed by 75% of these strains, and antibodies directed against these proteins are protective in animal models of infection. The purpose of the present study was to define the functional activity of human antibodies specific for these proteins in an in vitro complement-dependent opsonophagocytic assay. Human promyelocytic cell line HL-60 served as the source of phagocytic cells, and a commercial preparation of intravenous immunoglobulin (IVIG) served as the source of human antibodies. High-molecular-weight (HMW) proteins were purified from four prototype nontypeable H. influenzae strains and used to prepare solid-phase affinity columns. IVIG was adsorbed on each column to remove strain-specific anti-HMW antibodies and to allow recovery of affinity-purified anti-HMW antibody fractions. Unadsorbed IVIG killed each of the prototype strains at titers of 1:80 to 1:320. HMW-adsorbed sera demonstrated fourfold decreases in opsonophagocytic titer against the homologous strains compared to unadsorbed IVIG. Affinity-purified anti-HMW antibody preparations demonstrated opsonophagocytic titers of 1:20 to 1:80 against the respective homologous strains and opsonophagocytic titers as high as 1:80 against heterologous strains. None of the affinity-purified anti-HMW antibody preparations was opsonophagocytic for a representative nontypeable H. influenzae strain that did not express HMW1- or HMW2-like proteins. These data demonstrate that human antibodies specific for the HMW1/HMW2-like adhesion proteins of nontypeable H. influenzae are opsonophagocytic and that such antibodies recognize epitopes shared by the HMW proteins of unrelated nontypeable H. influenzae strains. These results argue for continued investigation of the HMW1/HMW2-like proteins as potential vaccine candidates for prevention of disease due to nontypeable H. influenzae.

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Koopman, Gerrit, Petra Mooij, Liesbeth Dekking, Daniëlla Mortier, Ivonne G. Nieuwenhuis, Melanie van Heteren, Harmjan Kuipers, Edmond J. Remarque, Katarina Radošević et Willy M. J. M. Bogers. « Correlation between Virus Replication and Antibody Responses in Macaques following Infection with Pandemic Influenza A Virus ». Journal of Virology 90, n^o 2 (4 novembre 2015) : 1023–33. http://dx.doi.org/10.1128/jvi.02757-15.

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ABSTRACTInfluenza virus infection of nonhuman primates is a well-established animal model for studying pathogenesis and for evaluating prophylactic and therapeutic intervention strategies. However, usually a standard dose is used for the infection, and there is no information on the relation between challenge dose and virus replication or the induction of immune responses. Such information is also very scarce for humans and largely confined to evaluation of attenuated virus strains. Here, we have compared the effect of a commonly used dose (4 × 10650% tissue culture infective doses) versus a 100-fold-higher dose, administered by intrabronchial installation, to two groups of 6 cynomolgus macaques. Animals infected with the high virus dose showed more fever and had higher peak levels of gamma interferon in the blood. However, virus replication in the trachea was not significantly different between the groups, although in 2 out of 6 animals from the high-dose group it was present at higher levels and for a longer duration. The virus-specific antibody response was not significantly different between the groups. However, antibody enzyme-linked immunosorbent assay, virus neutralization, and hemagglutination inhibition antibody titers correlated with cumulative virus production in the trachea. In conclusion, using influenza virus infection in cynomolgus macaques as a model, we demonstrated a relationship between the level of virus production upon infection and induction of functional antibody responses against the virus.IMPORTANCEThere is only very limited information on the effect of virus inoculation dose on the level of virus production and the induction of adaptive immune responses in humans or nonhuman primates. We found only a marginal and variable effect of virus dose on virus production in the trachea but a significant effect on body temperature. The induction of functional antibody responses, including virus neutralization titer, hemagglutination inhibition titer, and antibody-dependent cell-mediated cytotoxicity, correlated with the level of virus replication measured in the trachea. The study reveals a relationship between virus production and functional antibody formation, which could be relevant in defining appropriate criteria for new influenza virus vaccine candidates.

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Moraschini, Luca, Irene Passalacqua, Monica Fabbrini, Immaculada Margarit Y Ros et Fabio Rigat. « Threshold-free estimation of functional antibody titers of a group B streptococcus opsonophagocytic killing assay ». Pharmaceutical Statistics 14, n^o 3 (16 février 2015) : 189–97. http://dx.doi.org/10.1002/pst.1673.

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Scully, Ingrid L., Mark W. Cutler, Seema Gangolli, Todd Belanger, David Cooper, Thomas Jones, Andrew McKeen et al. « 1337. Development, Maintenance, and Application of Opsonophagocytic Assays to Measure Functional Antibody Responses to Support a 20 Valent Pneumococcal Conjugate Vaccine ». Open Forum Infectious Diseases 6, Supplement_2 (octobre 2019) : S484. http://dx.doi.org/10.1093/ofid/ofz360.1201.

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Abstract Background Opsonophagocytic assays (OPAs) are an important tool for assessing vaccine-induced functional antibody responses. OPAs are complex assays composed of many biological components (eg serum, complement sources, bacteria, and human phagocytes) which contribute to assay variability and may result in titer drift if not carefully controlled. Rigorous development and validation coupled with routine monitoring of assay performance are required to ensure that high-quality OPA serological data are consistently generated throughout the lifetime of existing and next-generation pneumococcal vaccines. Methods OPA specificity was demonstrated by competing functional antibody activity with pneumococcal polysaccharides. Assay qualification/validation assessed accuracy, precision, and sample linearity. Assay performance over time was assessed through the implementation of quality control serum data tracking systems and longterm serum proficiency panels that are routinely tested during assay performance. Human quality control sera are included on each assay plate to ensure that each plate meets pre-specified acceptance criteria. Proficiency serum panels are comprised of individual human serum samples derived from subjects immunized with pneumococcal vaccines and are used to monitor performance across a range of serological titers and over time. Results The OPAs were shown to be specific and reproducible. Monitoring of assay performance over time demonstrated that the assays are stable. For the 13 serotypes contained in 13vPnC reliable titers have been generated in over a decade of testing which is an essential prerequisite in the evaluation of next-generation pneumococcal conjugate vaccines such as 20vPnC, whose licensure depends on demonstration of non-inferiority to 13vPnC. Conclusion Maintenance and careful monitoring of high-quality assays to measure functional antibody responses, such as OPAs, is critical for the delivery of reliable serological data to support the advancement of pneumococcal vaccine programs. Pneumococcal OPAs must be rigorously maintained to ensure continuity of serological data over time and inform licensure decisions of next-generation vaccines as well as postmarketing and seroepidemiology studies. Disclosures All authors: No reported disclosures.

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Concepcion, Nelydia F., et Carl E. Frasch. « Pneumococcal Type 22F Polysaccharide Absorption Improves the Specificity of a Pneumococcal-Polysaccharide Enzyme-Linked Immunosorbent Assay ». Clinical Diagnostic Laboratory Immunology 8, n^o 2 (1 mars 2001) : 266–72. http://dx.doi.org/10.1128/cdli.8.2.266-272.2001.

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ABSTRACT The specificity of the immune response to the 23-valent pneumococcal-polysaccharide (PS) vaccine in healthy adults and to a pneumococcal conjugate vaccine in infants was examined by measuring immunoglobulin G (IgG) antibody titers by enzyme-linked immunosorbent assay (ELISA) and the opsonophagocytosis assay. ELISA measures total antipneumococcal IgG titers including the titers of functional and nonfunctional antibodies, while the opsonophagocytosis assay measures only functional-antibody titers. Twenty-four pairs of pre- and post-pneumococcal vaccination sera from adults were evaluated (ELISA) for levels of IgG antibodies against serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F. Twelve of the pairs were also examined (opsonophagocytosis assay) for their functional activities. The correlation coefficients between assay results for most types ranged from 0.75 to 0.90, but the correlation coefficient was only about 0.6 for serotypes 4 and 19F. The specificities of these antibodies were further examined by the use of competitive ELISA inhibition. A number of heterologous polysaccharides (types 11A, 12F, 15B, 22F, and 33A) were used as inhibitors. Most of the sera tested showed cross-reacting antibodies, in addition to those removed by pneumococcal C PS absorption. Our data suggest the presence of a common epitope that is found on most pneumococcal PS but that is not absorbed by purified C PS. Use of a heterologous pneumococcal PS (22F) to adsorb the antibodies to the common epitope increased the correlation between the IgG ELISA results and the opsonophagocytosis assay results. The correlation coefficient improve from 0.66 to 0.92 for type 4 and from 0.63 to 0.80 for type 19F. These common-epitope antibodies were largely absent in infants at 7 months of age, suggesting the carbohydrate nature of the epitope.

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Sola, Isabel, Joaquín Castilla, Belén Pintado, José M. Sánchez-Morgado, C. Bruce A. Whitelaw, A. John Clark et Luis Enjuanes. « Transgenic Mice Secreting Coronavirus Neutralizing Antibodies into the Milk ». Journal of Virology 72, n^o 5 (1 mai 1998) : 3762–72. http://dx.doi.org/10.1128/jvi.72.5.3762-3772.1998.

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ABSTRACT Ten lines of transgenic mice secreting transmissible gastroenteritis coronavirus (TGEV) neutralizing recombinant monoclonal antibodies (rMAbs) into the milk were generated. The rMAb light- and heavy-chain genes were assembled by fusing the genes encoding the variable modules of the murine MAb 6A.C3, which binds an interspecies conserved coronavirus epitope essential for virus infectivity, and a constant module from a porcine myeloma with the immunoglobulin A (IgA) isotype. The chimeric antibody led to dimer formation in the presence of J chain. The neutralization specific activity of the recombinant antibody produced in transiently or stably transformed cells was 50-fold higher than that of a monomeric rMAb with the IgG1 isotype and an identical binding site. This rMAb had titers of up to 104 by radioimmunoassay (RIA) and neutralized virus infectivity up to 104-fold. Of 23 transgenic mice, 17 integrated both light and heavy chains, and at least 10 of them transmitted both genes to the progeny, leading to 100% of animals secreting functional TGEV neutralizing antibody during lactation. Selected mice produced milk with TGEV-specific antibody titers higher than 106 as determined by RIA, neutralized virus infectivity by 106-fold, and produced up to 6 mg of antibody per ml. Antibody expression levels were transgene copy number independent and integration site dependent. Comicroinjection of the genomic β-lactoglobulin gene with rMAb light- and heavy-chain genes led to the generation of transgenic mice carrying the three transgenes. The highest antibody titers were produced by transgenic mice that had integrated the antibody and β-lactoglobulin genes, although the number of transgenic animals generated does not allow a definitive conclusion on the enhancing effect of β-lactoglobulin cointegration. This approach may lead to the generation of transgenic animals providing lactogenic immunity to their progeny against enteric pathogens.

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Zhang, Q., S. Choo, J. Everard, R. Jennings et A. Finn. « Mucosal Immune Responses to Meningococcal Group C Conjugate and Group A and C Polysaccharide Vaccines in Adolescents ». Infection and Immunity 68, n^o 5 (1 mai 2000) : 2692–97. http://dx.doi.org/10.1128/iai.68.5.2692-2697.2000.

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ABSTRACT Previous studies in children have shown that Haemophilus influenzae type b (Hib) polysaccharide conjugate vaccines can reduce nasopharyngeal carriage of H. influenzae and provide herd immunity and suggest that this effect is mediated through mucosal antibodies. As this phenomenon may operate in other invasive bacterial infections which are propagated by nasopharyngeal carriage, mucosal antibody responses to meningococcal C conjugate and A/C polysaccharide vaccines were investigated. A total of 106 school children aged 11 to 17 years were randomized to receive a single dose of either conjugate or polysaccharide vaccine in an observer-blind study. Before and at 1, 6, and 12 months after immunization, samples of unstimulated saliva were collected and assayed by enzyme-linked immunosorbent assay for group C polysaccharide-specific immunoglobulin A (IgA), IgA1, IgA2 and secretory component, IgG antibodies, and total IgG and IgA. A subset of serum samples were also assayed for specific IgA and IgG antibodies. The concentrations of specific IgA and IgG in saliva were expressed both as nanograms per milliliter and as nanograms per microgram of total IgA or IgG. One month after immunization, significant increases in antibody titers (both IgA and IgG) were observed in saliva in both groups. There were significant subsequent falls in antibody titers by 6 months. Anti-meningococcal C-specific secretory component and IgA antibody titers were closely correlated (r = 0.85,P < 0.001), but there was no significant correlation between salivary and serum IgA titers, suggesting that IgA antibodies are locally produced. Significant correlation was found between salivary and serum IgG titers (r = 0.52,P < 0.01), suggesting that salivary IgG may be serum derived. Compared with polysaccharide vaccine, the conjugate vaccine induced significantly higher salivary IgG responses (P< 0.05), although there were no significant differences between salivary IgA responses to the two vaccines. The conjugate vaccine induced greater salivary IgG responses than a polysaccharide vaccine. Both vaccines induced significant salivary IgA antibodies. Further studies are needed to establish the functional significance of these mucosal responses.

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Powell, T. J., R. Spann, M. Vakil, J. F. Kearney et E. W. Lamon. « Activation of a functional idiotype network response by monoclonal antibody specific for a virus (M-MuLV)-induced tumor antigen. » Journal of Immunology 140, n^o 9 (1 mai 1988) : 3266–72. http://dx.doi.org/10.4049/jimmunol.140.9.3266.

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Abstract BALB/c mice were injected with IgM mAb specific for Moloney murine leukemia virus (M-MuLV)-determined cell surface Ag in an attempt to inhibit Moloney sarcoma growth. The monoclonal IgM significantly inhibited sarcoma growth when given to the mice after inoculation with Moloney murine sarcoma/leukemia virus, and also potentiated the in vivo antibody response specific for M-MuLV Ag. These responses were significantly greater than the primary response to the virus alone in age- and sex-matched control mice, and were also seen in mice which were injected with the IgM antibody only and not with virus, suggesting that an Ag-independent mechanism may be involved. The M-MuLV-specific serum antibody responses induced by the monoclonal IgM, with or without prior virus inoculation, were predominantly of the IgG1 isotype, with some IgG2a; no other isotypes were found to have titers significantly higher than in the normal response to virus alone. M-MuLV-specific IgG1 was detected only in mice injected with monoclonal IgM, and not in the response to virus alone. The same sera also had high titers of anti-idiotypic antibodies, (Ab2), as well as anti-anti-idiotypic antibodies (Ab3). It appears, therefore, that passive immunization with M-MuLV-specific IgM mAb activates an idiotypic network, which results in both Ab2 and Ab3 responses; the M-MuLV-specific response may be considered a subset of Ab3.

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Zhu, Daniel Y., Matthew J. Gorman, Dansu Yuan, Jingyou Yu, Noe B. Mercado, Katherine McMahan, Erica N. Borducchi et al. « Defining the determinants of protection against SARS-CoV-2 infection and viral control in a dose-down Ad26.CoV2.S vaccine study in nonhuman primates ». PLOS Biology 20, n^o 5 (5 mai 2022) : e3001609. http://dx.doi.org/10.1371/journal.pbio.3001609.

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Despite the rapid creation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) vaccines, the precise correlates of immunity against severe Coronavirus Disease 2019 (COVID-19) are still unknown. Neutralizing antibodies represent a robust surrogate of protection in early Phase III studies, but vaccines provide protection prior to the evolution of neutralization, vaccines provide protection against variants that evade neutralization, and vaccines continue to provide protection against disease severity in the setting of waning neutralizing titers. Thus, in this study, using an Ad26.CoV2.S dose-down approach in nonhuman primates (NHPs), the role of neutralization, Fc effector function, and T-cell immunity were collectively probed against infection as well as against viral control. While dosing-down minimally impacted neutralizing and binding antibody titers, Fc receptor binding and functional antibody levels were induced in a highly dose-dependent manner. Neutralizing antibody and Fc receptor binding titers, but minimally T cells, were linked to the prevention of transmission. Conversely, Fc receptor binding/function and T cells were linked to antiviral control, with a minimal role for neutralization. These data point to dichotomous roles of neutralization and T-cell function in protection against transmission and disease severity and a continuous role for Fc effector function as a correlate of immunity key to halting and controlling SARS-CoV-2 and emerging variants.

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Centkowski, Piotr, Lidia B. Brydak, Magdalena Machala, Ewa Kalinka, Maria Blasinska-Morawiec, Irena Federowicz, Jan Walewski et al. « Immunogenicity of Influenza Vaccination in Patients with Non-Hodgkin Lymphoma : Final Report after Two Epidemic Seasons. » Blood 108, n^o 11 (16 novembre 2006) : 4598. http://dx.doi.org/10.1182/blood.v108.11.4598.4598.

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Abstract Vaccination against influenza is recommended for immunocompromised individuals. However, there is little information concerning the efficacy of vaccination in patients (pts) with non-Hodgkin lymphoma (NHL). The purpose of this study was to assess humoral response to standard intramuscular trivalent subunit influenza vaccine in pts with NHL as compared to healthy subjects. In two consecutive epidemic seasons, 2003/2004 and 2004/2005, 163 pts and 92 healthy controls were vaccinated. Antibody titers to hemagglutinin (HA) and neuraminidase (NA) were measured in serum samples collected before vaccination, and 1 and 6 months apart. Changes in the hemagglutination inhibition (HAI) and neuraminidase inhibition (NII) antibody titers were assessed by comparing geometric mean titers and mean fold increases to baseline values and by comparing changes in the HA seroconversion and seroprotection rates. Pts who received influenza vaccine during 2003/2004 season had after one month increases in the geometric mean titers by a factor of 8,64–26,60 for HI and 6,93–12,66 for NI, as compared with respective increases by a factor of 9,12–24,41 and 4,83–10,31 for the healthy controls. At one month after vaccination seroprotection and seroresponse rates were similar in the two groups, ranging from 68,42 to 84,21 % and 71,93 to 94,74 % in NHL and 66,67–82,22 % and 62,22–86,67 % in controls, respectively. After six months, seroprotection and seroresponse rates had decreased in NHL group to 31,91–38,30% and 46,81–72,34%, respectively. Pts who received influenza vaccine during 2004/2005 season had after 1 month increases in the geometric mean titers by a factor of 38,76–41,49 for HI and 26,59–30,31 for NI, as compared with respective increases by a factor of 81,19–104,32 and 52,16–54,52 for the healthy controls. Seroprotection and seroresponse rates were lower in the former group, ranging from 62,11 to 65,26 % and 74,47 to 77,66 %, respectively. After six months, these parameters had decreased to 24,72–31,46% and 57,30–59,55%, respectively. In both studied seasons, pts achieved titres of functional antibodies greater than the protective threshold, irrespective of the previous chemotherapy administration. The results of this study indicate that standard influenza vaccination induces sufficient immune responses in pts with NHL. Previous chemotherapy adminstration seems to have no impact on the efficacy of vaccination.

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Karlsson, Johanna, Lucy Roalfe, Harriet Hogevik, Marta Zancolli, Björn Andréasson, David Goldblatt et Christine Wennerås. « Poor Correlation between Pneumococcal IgG and IgM Titers and Opsonophagocytic Activity in Vaccinated Patients with Multiple Myeloma and Waldenstrom's Macroglobulinemia ». Clinical and Vaccine Immunology 23, n^o 4 (24 février 2016) : 379–85. http://dx.doi.org/10.1128/cvi.00654-15.

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ABSTRACTPatients with multiple myeloma and other B cell disorders respond poorly to pneumococcal vaccination. Vaccine responsiveness is commonly determined by measuring pneumococcal serotype-specific antibodies by enzyme-linked immunosorbent assay (ELISA), by a functional opsonophagocytosis assay (OPA), or by both assays. We compared the two methods in vaccinated elderly patients with multiple myeloma, Waldenstrom's macroglobulinemia, and monoclonal gammopathy of undetermined significance (MGUS). Postvaccination sera from 45 patients (n= 15 from each patient group) and 15 control subjects were analyzed by multiplexed OPA for pneumococcal serotypes 4, 6B, 14, and 23F, and the results were compared to IgG and IgM antibody titers measured by ELISA. While there were significant correlations between pneumococcal OPA and IgG titers for all serotypes among the control subjects (correlation coefficients [r] between 0.51 and 0.85), no significant correlations were seen for any of the investigated serotypes in the myeloma group (r= −0.18 to 0.21) or in the group with Waldenstrom's macroglobulinemia (borderline significant correlations for 2 of 4 serotypes). The MGUS group resembled the control group by having good agreement between the two test methods for 3 of 4 serotypes (r= 0.53 to 0.80). Pneumococcal postvaccination IgM titers were very low in the myeloma patients compared to the other groups and did not correlate with the OPA results. To summarize, our data indicate that ELISA measurements may overestimate antipneumococcal immunity in elderly subjects with B cell malignancies and that a functional antibody test should be used specifically for myeloma and Waldenstrom's macroglobulinemia patients.

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Sembiring, Bagem BR, Ening Wiedosari et Sujianto Sujianto. « THE EFFECT OF JAMU FORMULAS ON BODY WEIGHT, ANTIOXIDANT ACTIVITIES, AND ANTIBODY TITER IN CHICKEN / Pengaruh Jenis Jamu terhadap Bobot Badan, Aktivitas Antioksidan dan Titer Antibodi Ayam ». Jurnal Penelitian Tanaman Industri 24, n^o 2 (4 décembre 2018) : 65. http://dx.doi.org/10.21082/littri.v24n2.2018.65-74.

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Medicinal plants are useful to increase body immunity, body weight, appetite, and improve health both for human and animal. The research aimed to obtain functional drink formula for chicken, called jamu, made with spices and medicinal plants. These trials consisted of 3 activities; first, raw materials preparation include fermentation and extraction, second, functional drink formulation in form liquid and powder with pH and IC50 value as parameters, third, efficacy test of formulas that had the strongest antioxidant. The treatments were categorized as group I (chicken were fed with jamu, without vaccination), group II (fed with jamu for two weeks then vaccinated), group III (jamu feeding complemented by vaccination), group IV (control, only vaccination). The third activity was arranged in a randomized block design with 6 replications. Parameters observed were body weight increment and antibody titer. The fermentation time and formula composition showed no significant effect on pH until the third day (4.31 - 4.68), but they indicated significant effect on pH from the fourth day, declined until the seventh day (3.65-4.26). The type and compositions of the formula significantly affected IC50 value. The smallest of IC50 value of liquid and powder formulas were 7796.25 ppm and 244.57 ppm, respectively. The incremental body weight regarding liquid, powder, and control formulas were 365.55 g / week, 351.22 g / week, and 326.66 g / week, respectively. The highest antibody titer was at group III that had 4.50 (log 2), whereas control was 3.30 (log2). The combination feeding, jamu formula and vaccine, was able to increase body weight increment and antibody titer on chicken.Keywords: medicinal plants, functional drink, IC50, broilers, antibody titers AbstrakTanaman obat digunakan untuk meningkatkan daya tahan tubuh, bobot badan, nafsu makan, mencegah penyakit, serta pemulihan kesehatan manusia dan hewan. Penelitian bertujuan mendapatkan formula minuman fungsional untuk ayam berbasis tanaman rempah dan obat. Kegiatan meliputi 3 aktivitas (1) Penanganan bahan baku, fermentasi dan ekstraksi (2) Formulasi minuman fungsional (cair dan serbuk) dengan parameter pH dan nilai IC50. (3) Uji efikasi formula cair dan serbuk yang menghasilkan aktivitas antioksidan terkuat. Perlakuan: kelompok I, ayam hanya diberi formula jamu selama dua minggu, kelompok II, ayam diberi formula jamu selama dua minggu sebelum vaksinasi, kelompok III, ayam divaksin sebelum diberi formula jamu selama dua minggu, kelompok IV, ayam hanya divaksinasi. Kegiatan (3) menggunakan Rancangan Acak Kelompok dengan 6 ulangan dan parameter pengamatan yaitu penambahan bobot badan dan titer antibodi. Waktu fermentasi dan komposisi formula tidak menunjukkan efek yang signifikan pada pH sampai hari ketiga (4,31-4,68), namun signifikan pada hari keempat ditandai dengan penurunan pH sampai hari ketujuh (3,65-4,26). Jenis dan komposisi formula secara signifikan mempengaruhi nilai IC50. Nilai IC50 terkecil dari formula cair adalah 7796,25 ppm dan serbuk 244,57 ppm. Kenaikan berat badan dengan formula jamu cair yaitu 365,55 g / minggu, serbuk 351,22 g / minggu dan kontrol 326,66 g / minggu. Titer antibodi tertinggi adalah 4,50 (log2) yang ditunjukkan oleh kelompok III, sedangkan kontrol 3,30 (log2). Minuman fungsional (jamu) ditambah dengan vaksinasi mampu meningkatkan pertambahan berat badan dan titer antibodi ayam.Kata kunci: Tanaman obat, minuman fungsional, IC50, ayam broiler, titer antibodi

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Chootong, Patchanee, Francis B. Ntumngia, Kelley M. VanBuskirk, Jia Xainli, Jennifer L. Cole-Tobian, Christopher O. Campbell, Tresa S. Fraser, Christopher L. King et John H. Adams. « Mapping Epitopes of the Plasmodium vivax Duffy Binding Protein with Naturally Acquired Inhibitory Antibodies ». Infection and Immunity 78, n^o 3 (14 décembre 2009) : 1089–95. http://dx.doi.org/10.1128/iai.01036-09.

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ABSTRACT Plasmodium vivax Duffy binding protein (DBP) is a merozoite microneme ligand vital for blood-stage infection, which makes it an important candidate vaccine for antibody-mediated immunity against vivax malaria. A differential screen with a linear peptide array compared the reactivities of noninhibitory and inhibitory high-titer human immune sera to identify target epitopes associated with protective immunity. Naturally acquired anti-DBP-specific serologic responses observed in the residents of a region of Papua New Guinea where P. vivax is highly endemic exhibited significant changes in DBP-specific titers over time. The anti-DBP functional inhibition for each serum ranged from complete inhibition to no inhibition even for high-titer responders to the DBP, indicating that epitope specificity is important. Inhibitory immune human antibodies identified specific B-cell linear epitopes on the DBP (SalI) ligand domain that showed significant correlations with inhibitory responses. Affinity-purified naturally acquired antibodies on these epitopes inhibited the DBP erythrocyte binding function greatly, confirming the protective value of specific epitopes. These results represent an important advance in our understanding of part of blood-stage immunity to P. vivax and some of the specific targets for vaccine-elicited antibody protection.

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Albert, Christian, Marie Schultzendorff, Delia Şalaru, Zuhir Halloul, Duska Dragun, Harald Heidecke et Peter R. Mertens. « In arterial occlusive disease autoantibodies against ETAR and AT1R correlate with each other but are not associated with classical cardiovascular risk factors ». Vasa 43, n^o 2 (1 mars 2014) : 113–23. http://dx.doi.org/10.1024/0301-1526/a000337.

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Background: Autoantibodies (Abs) against angiotensin-II type 1 (AT1R) and endothelin-1 type A receptors (ETAR) are investigated in the present study as B-cell originated humoral factors that may activate the respective receptors on endothelial cells. The prevalence of the Abs was determined in patients with peripheral arterial occlusive disease (PAD). Patients and methods: In a prospective observational study 200 patients undergoing angiography and proven advanced PAD were enrolled. Serum samples, clinical data and laboratory values for classical cardiovascular risk factors were collected. Autoantibody titers for AT1R and ETAR were determined by solid-phase ELISA and correlative analyses with laboratory parameters and clinical data for common cardiovascular risk factors were performed. Results: Anti-ETAR antibody titers were detected in 57 % of the patients, elevated anti-AT1R titers in 61.5 %. About 50 % were positive for both Abs. A strong intercorrelation between ETAR and AT1R titers was present (r2 0.79). In patients with positive titers for both Abs females presented significantly higher titers for ETAR (p = 0.045) and AT1R (p = 0.02). Autoantibody titers directed against surface receptors ETA and AT1 are highly correlated in PAD. Titers were independent from classical risk factors in any patient subgroup. Conclusions: This study opens a new perspective on the involvement of the immune system, hereby represented by functional autoantibodies, in the atherosclerotic pathophysiology, leaving behind the common background of classical risk factors.

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Schumack, Nina M., Joanna E. Rimmer, Patricia Guerry et Renee M. Laird. « Functional complement-fixing antibodies are generated against a Campylobacter jejuni capsule conjugate vaccine in non-human primates ». Journal of Immunology 196, n^o 1_Supplement (1 mai 2016) : 146.22. http://dx.doi.org/10.4049/jimmunol.196.supp.146.22.

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Abstract Campylobacter jejuni is among the most common causes of diarrheal disease worldwide and efforts to develop protective measures against the pathogen are ongoing. One of the few defined virulence factors targeted for vaccine development is the capsule polysaccharide (CPS). We have developed a capsule conjugate vaccine against a prototype CPS, type HS23/36, that confers 100% protection against diarrhea caused by a homologous strain of C. jejuni in a non-human primate (NHP) model; however the mechanisms of protection remain unknown. Other licensed capsule conjugate vaccines against encapsulated gram-negative organisms use bactericidal antibody titers as a correlate of protection. We developed a flow cytometry-based serum bactericidal assay (SBA) to determine if increased levels of complement-fixing antibodies correlate with protection against C. jejuni. Sera from NHPs immunized with HS23/36 CPS-CRM197 vaccine showed significantly higher SBA titers when compared with control NHPs. Results were similar to those of a bacteriological-based SBA. All NHPs, irrespective of immune status, that did not develop diarrhea, had higher SBA titers compared with NHPs that developed diarrhea. Importantly, a strong correlation was found between serum anti-CPS IgG and SBA titers in NHPs and similar studies will be conducted in upcoming human clinical trials. This flow cytometry-based SBA assay is much simpler than bacteriological-based assays and should facilitate analyses of functional antibodies against multivalent C. jejuni capsule conjugate vaccines.

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Gapel’chenkova, T. V., R. Z. Shaikhutdinova, A. S. Trunyakova, T. E. Svetoch, T. I. Kombarova, M. E. Platonov, A. I. Borzilov, P. Kh Kopylov et S. V. Dentovskaya. « Dynamics of Antibody Response to Yersinia pestis ; Proteins in Plague Affected Guinea Pigs ». Problems of Particularly Dangerous Infections, n^o 4 (11 février 2023) : 50–56. http://dx.doi.org/10.21055/0370-1069-2022-4-50-56.

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Designing of new means for the specific prevention of plague, especially protein subunit vaccines, is impossible without studying the role of individual antigens in the manifestation of the pathogenic and immunogenic properties of Yersinia pestis. The aim of the present study was to determine the antibody levels to Y. pestis antigens in guinea pigs that survived infection with sub-lethal doses of virulent plague agent strains using enzyme immunoassay (ELISA). Materials and methods. Guinea pigs were inoculated subcutaneously with 30 CFU of the wild type Y. pestis subsp. Pestis strain 231 or non-capsular Y. pestis subsp. pestis Caf1-negative strain 358/12. Blood samples from sick or recovered guinea pigs were collected on day 15, 30, 60, and 90 after infection. The antibody response was assessed by 18 recombinant Y. pestis proteins in ELISA. Results and discussion. Heterogeneity of the antibody responses to the majority of the antigens with variation of IgG titers from animal to animal has been revealed. We observed increase in antibody titers by day 90 for the most analyzed antigens in the sera of the guinea pigs injected with wild type Y. pestis 231. On the contrary we found reduction in antibody titers by day 90 in case of inoculation with Y. pestis 358/12. The preservation of antibodies to Y. pestis proteins of different localization in the organism of the guinea pigs, as well functional activity, and the degree of representation on the surface of bacterial cell for a prolonged period of time indicates the multiplex nature of the plague immunity formation. Our ﬁndings are significant for the future design and development of effective vaccines against plague and the search for new targets for diagnostics of this disease.

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Rose, Charles E., Sandra Romero-Steiner, Robert L. Burton, George M. Carlone, David Goldblatt, Moon H. Nahm, Lindsey Ashton et al. « Multilaboratory Comparison ofStreptococcus pneumoniaeOpsonophagocytic Killing Assays and Their Level of Agreement for the Determination of Functional Antibody Activity in Human Reference Sera ». Clinical and Vaccine Immunology 18, n^o 1 (17 novembre 2010) : 135–42. http://dx.doi.org/10.1128/cvi.00370-10.

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ABSTRACTAntibody-mediated killing ofStreptococcus pneumoniae(pneumococcus) by phagocytes is an important mechanism of protection of the human host against pneumococcal infections. Measurement of opsonophagocytic antibodies by use of a standardized opsonophagocytic assay (OPA) is important for the evaluation of candidate vaccines and required for the licensure of new pneumococcal conjugate vaccine formulations. We assessed agreement among six laboratories that used their own optimized OPAs on a panel of 16 human reference sera for 13 pneumococcal serotypes. Consensus titers, estimated using an analysis-of-variance (ANOVA) mixed-effects model, provided a common reference for assessing agreement among these laboratories. Agreement was evaluated in terms of assay accuracy, reproducibility, repeatability, precision, and bias. We also reviewed four acceptance criterion intervals for assessing the comparability of protocols when assaying the same reference sera. The precision, accuracy, and concordance results among laboratories and the consensus titers revealed acceptable agreement. The results of this study indicate that the bioassays evaluated in this study are robust, and the resultant OPA values are reproducible for the determination of functional antibody titers specific to 13 pneumococcal serotypes when performed by laboratories using highly standardized but not identical assays. The statistical methodologies employed in this study may serve as a template for evaluating future multilaboratory studies.

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Ho, Thuy N., Maheen Khan, Bennett Clark, Elizabeth Krieger, Catherine H. Roberts et Amir Ahmed Toor. « Functional B Cell Reconstitution Following Allogeneic Stem Cell Transplantation ». Blood 136, Supplement 1 (5 novembre 2020) : 40. http://dx.doi.org/10.1182/blood-2020-142799.

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Immune reconstitution is critical to long term survivability in recipients of allogeneic hematopoietic cell transplantation (HCT), mitigating both relapse as well as infection risk. However, both graft versus host disease (GVHD) and post HCT immunosuppression used to prevent it impair immune recovery, particularly functional B cell reconstitution which may not happen for several months post-transplant. This is relevant for post-transplant vaccination which in some centers is delayed till immune cell recovery. In this retrospective, Virginia Commonwealth University institutional review board (IRB) approved study, T helper and B cell recovery for up to two years following HCT was evaluated in 212 patients transplanted between 2015 and 2019. There were 69 HLA matched related & 143 unrelated donor transplant recipients. Median age of the patients was 56 years (range 19-74); conditioning regimens utilized were reduced intensity (RIC) in ~62% of the patients and rabbit anti-thymocyte globulin was used in ~72% of the patients. Blood stem cells were given in 183 patients and bone marrow in 29. Only patients with hematological malignancies were included in this study. Landmark analysis was carried out, with patients who did not survive the first 6 months post-transplant excluded. Of these patients, 85% are surviving. Median CD3+/4+ (Th) cell counts were 153 at 6 months, 228 at 1-year, 296 at 2 years, and corresponding B cell counts were 70, 175, & 273. Plotting Th and B cell counts over time in each individual donor-recipient pair demonstrated close correspondence between Th and B cell recovery, with synchronous recovery observed in most patients, median R 0.76 (range: 0.01-0.99). The slope of the B/Th cell curves for each patient then were compared in a subset of patients, and demonstrated a significant difference between those patients who either did not develop GVHD or only had acute GVHD as opposed to those who developed both acute and chronic GVHD (1.3±1.4 B cells/Th cells and 1.1±1.2 vs. 0.5±1, P=0.02 and 0.06 respectively), suggesting poor B cell recovery in those with chronic GVHD. Different immune recovery kinetics were observed amongst patients (Figure 1); A) rapid B cell recovery, highest absolute B cell count between 30 and 180 days post-HCT, B) intermediate B cell recovery, days 180 and 455, C) delayed B cell recovery, days 455 and 725 days, and D) minimal to no B cell recovery. A higher relative risk for developing acute + chronic GVHD was seen in the intermediate B cell recovery group when compared to those with delayed recovery, RR = 2.38 (95% CI 1.08-5.25). Functional B cell studies were performed in a subset, by measuring IgG levels and anti-pneumococcal antibody titers. Correlation was observed between Th cell count and IgG levels over time in individual patients (median R = 0.57). Pneumococcal titers were also measured at approximately 6 months, 1- and 2-years post-transplant as patients were given a series of PCV13 & PSV23 vaccinations 6 months after HCT. When the antibody titers against unique pneumococcal serotypes were analyzed in individual patients, these varied within each individual, following a declining trend in levels for antibodies against different serotypes; this decline occurred on a logarithmic scale suggesting differential immunogenicity of the pneumococcal antigens, and also mathematically ordered, rather than random Th and B cell responses (Figure 2A). When the serotypes with the highest titers in most patients were correlated with Th and B cell counts measured simultaneously, no association was observed. Further, when fold increase in pneumococcal titers beyond 1-year post transplant were compared across different groups of patients based on their GVHD status, no significant difference was observed in their antibody responses (Figure 2B). In conclusion, our data suggest synchronous Th and B cell reconstitution post allogeneic HCT, both in numeric and functional terms, and thus strategies to help promote T cell recovery, such as IL-7 administration post-transplant, are necessary to encourage optimal immune reconstitution. Vaccine responses beyond 6 months, as in the institutional practice reported here, are independent of GVHD status and numeric immune cellular recovery. These findings are consistent with the notion that immune recovery is a dynamical, rather than a stochastic process. Disclosures No relevant conflicts of interest to declare.

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Devera, T. Scott, Gillian A. Lang, Jordi M. Lanis, Pragya Rampuria, Casey L. Gilmore, Judith A. James, Jimmy D. Ballard et Mark L. Lang. « Memory B Cells Encode Neutralizing Antibody Specific for Toxin B from the Clostridium difficile Strains VPI 10463 and NAP1/BI/027 but with Superior Neutralization of VPI 10463 Toxin B ». Infection and Immunity 84, n^o 1 (26 octobre 2015) : 194–204. http://dx.doi.org/10.1128/iai.00011-15.

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Secreted toxin B (TcdB) substantially contributes to the pathology observed duringClostridium difficileinfection. To be successfully incorporated into a vaccine, TcdB-based immunogens must stimulate the production of neutralizing antibody (Ab)-encoding memory B cells (Bmem cells). Despite numerous investigations, a clear analysis of Bmem cellular responses following vaccination against TcdB is lacking. B6 mice were therefore used to test the ability of a nontoxigenic C-terminal domain (CTD) fragment of TcdB to induce Bmem cells that encode TcdB-neutralizing antibody. CTD was produced from the historical VPI 10463 strain (CTD1) and from the hypervirulent strain NAP1/BI/027 (CTD2). It was then demonstrated that CTD1 induced strong recall IgG antibody titers, and this led to the development of functional Bmem cells that could be adoptively transferred to naive recipients. Bmem cell-driven neutralizing Ab responses conferred protection against lethal challenge with TcdB1. Further experiments revealed that an experimental adjuvant (Imject) and a clinical adjuvant (Alhydrogel) were compatible with Bmem cell induction. Reactivity of human Bmem cells to CTD1 was also evident in human peripheral blood mononuclear cells (PBMCs), suggesting that CTD1 could be a good vaccine immunogen. However, CTD2 induced strong Bmem cell-driven antibody titers, and the CTD2 antibody was neutralizingin vitro, but its protection against lethal challenge with TcdB2 was limited to delaying time to death. Therefore, CTD from differentC. difficilestrains may be a good immunogen for stimulating B cell memory that encodesin vitroneutralizing Ab but may be limited by variable protection against intoxicationin vivo.

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Ohm, Milou, Debbie M. van Rooijen, Axel A. Bonačić Marinović, Mariëtte B. van Ravenhorst, Marieke van der Heiden, Anne-Marie Buisman, Elisabeth A. M. Sanders et Guy A. M. Berbers. « Different Long-Term Duration of Seroprotection against Neisseria meningitidis in Adolescents and Middle-Aged Adults after a Single Meningococcal ACWY Conjugate Vaccination in The Netherlands ». Vaccines 8, n^o 4 (25 octobre 2020) : 624. http://dx.doi.org/10.3390/vaccines8040624.

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Neisseria meningitidis is often asymptomatically carried in the nasopharynx but may cause invasive meningococcal disease, leading to morbidity and mortality. Meningococcal conjugate vaccinations induce functional protective antibodies against capsular antigens, but seroprotection wanes over time. We measured functional antibody titers five years after administration of a single dose of the meningococcal ACWY-polysaccharide-specific tetanus toxoid-conjugated (MenACWY-TT) vaccine in adolescents and middle-aged adults in the Netherlands, using the serum bactericidal antibody with baby rabbit complement (rSBA) assay. Protection was defined as rSBA titer ≥8. The meningococcal ACWY-specific serum IgG concentrations were measured with a multiplex immunoassay. Duration of protection was estimated by a bi-exponential decay model. Sufficient protection for MenC, MenW, and MenY was achieved in 94–96% of the adolescents five years postvaccination, but, in middle-aged adults, only in 32% for MenC, 65% for MenW and 71% for MenY. Median duration of protection for MenCWY was 4, 14, and 21 years, respectively, in middle-aged adults, while, in adolescents, it was 32, 98, and 33 years. Our findings suggest that adolescents, primed in early childhood with MenC conjugate vaccination, remain sufficiently protected after a single dose of MenACWY-TT vaccine. Middle-aged adults without priming vaccination show fast waning of antibodies, particularly MenC, for which protection is lost after four years.

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Holovakha, V. I., A. O. Slyusarenko, O. S. Petrenko et N. I. Suslova. « Biochemical parameters of blood in cows in latent course of leptospirosis ». Regulatory Mechanisms in Biosystems 10, n^o 2 (20 juin 2019) : 182–86. http://dx.doi.org/10.15421/021927.

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Changes in the biochemical parameters of blood in cows in the latent course of leptospirosis have been studied by the results of the reaction of microagglutination (RMA). The dynamics of biochemical blood parameters is manifested by hyperproteinemia, dysproteinemia, hemolytic anemia, hyperbilirubinemia, intra- and extrahepatic cholestasis, hyperfermentemia, mineral metabolism disorders, in particular hypocalcemia, hypophosphatemia, indicating the development of hepatopathy which should be classified as hepatocholangitis. It was determined that the pathological process is manifested in all animals for the titer of antibodies to one or another Leptospira serovar. Significant changes from the side of the hepatobiliary system in infested cows for the antibody titer kabura equaling 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200, bratislava 1:800 and in animals for the titers kabura of 1:100–1:200; polonium 1:100; szvajzak 1:100–1:200; ballum 1:100; bratislava 1:100–1:200. At leptospirosis caused by bratislava and ballum serovars, a disorder of the functional state of the hepatobiliary system, characterized by an increase in the level of total protein, bilirubin, AST, GGTP and ALP activity was diagnosed as the urea, calcium and phosphorus levels in blood decreased. In the case of the latent course of the disease caused by kabura, polonica, szvajzak, ballumand bratislava serovars, a probably higher concentration of bilirubin, activity of aminotransferases (AST and ALAT), GGTP and ALP was determined in comparison to clinically healthy animals. In cows, in the presence of antibody titers kabura 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200; bratislava 1:800, in 22.2% of cases, we recorded increase in the total protein against the background of dysproteinemia in 50.0–88.9% of animals, and increase in bilirubin in 78.6%, and increase in the activity of blood serum enzymes (AST, ALAT, GGTP, ALP), and also hypocalcemia and hypophosphatemia in 33.3–100.0%. The conducted studies indicate that in latent leptospirosis in cows, in addition to etiotropic therapy, one should include in the protocol the pharmacological correction preparations, which would contribute to the restoration of the functional state of the hepatobiliary system.

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Hausl, Christina, Josenato Ilas, Christian Lubich, Rafi U. Ahmad, Eva M. Muchitsch, Hartmut Ehrlich, Hans Peter Schwarz et Birgit M. Reipert. « Naturally Occurring Regulatory T Cells Modulate Immune Responses Against Exogenous Factor VIII in Hemophilic Balb/c Mice but Not in C57BL/6J Mice. » Blood 110, n^o 11 (16 novembre 2007) : 1160. http://dx.doi.org/10.1182/blood.v110.11.1160.1160.

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Abstract Antibody responses against factor VIII (FVIII) are the major complication that arises when patients with hemophilia A are treated with factor VIII products. Therefore, understanding regulation of anti-FVIII immune responses is of outmost importance. Antibody responses are well established to result from differentiation of B cells into antibody-secreting plasma cells. B cells need help from activated CD4+ T cells to develop high-affinity antibody responses against protein antigens such as FVIII. Recently, naturally occurring CD4+CD25+ regulatory T cells have been shown to modulate antibody responses by either suppressing the function of CD4+ T helper cells or by directly acting on B cells. However, the potential importance of CD4+CD25+ T cells in regulating antibody responses to foreign protein antigens is controversial. Furthermore, the extent to which naturally occurring CD4+CD25+ T cells regulate antibody responses against exogenous proteins such as FVIII when these proteins are given to previously untreated patients is unclear. To obtain information on how important naturally occurring CD4+CD25+ T cells are under such conditions, we asked whether these cells regulate anti-FVIII antibody responses in murine hemophilia A. We studied E17 hemophilic mice with two different genetic backgrounds (C57BL/6J and Balb/c) and treated them with four intravenous doses of human FVIII given at weekly intervals. Before the first dose of FVIII, CD4+CD25+ T cells were depleted in vivo using an anti-CD25 antibody that has been shown to deplete naturally occurring CD4+CD25+ T cells in mice. In vivo depletion of regulatory T cells using the same antibody has been successfully applied in a variety of mouse studies to evaluate the significance of naturally occurring CD4+CD25+ T cells in different immunological systems. An isotype-matched control antibody was used as a negative control. A week after the second and the fourth dose of FVIII, plasma samples were taken and tested for anti-FVIII antibodies. We found differences in titers of anti-FVIII antibodies between mice treated with anti-CD25 antibodies and control mice in Balb/c mice but not in C57BL/6J mice. Hemophilic Balb/c mice that had been pre-treated with anti-CD25 antibodies developed higher titers of anti-FVIII antibodies than mice that had been pre-treated with an isotype-matched control antibody. Differences were seen as a statistical trend (p=0.091) after two doses of FVIII and reached statistical significance (p=0.024) after four doses of FVIII. No differences in antibody titers were observed in hemophilic C57BL/6J mice. Our results strongly indicate that the ability of naturally occurring regulatory T cells to modulate anti-FVIII antibody responses in hemophilic mice depends on the genetic background of these mice. Immunoregulatory factors such as cytokines or chemokines as well as differences in the number and functional activity of naturally occurring regulatory T cells that are found in secondary lymphoid organs are likely to determine the regulatory capacity of these cells. Based on our results we conclude that differences in number and functional activity of naturally occurring regulatory T cells should be considered in the search for risk factors associated with the development of FVIII inhibitors in patients.

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Feiring, Berit, Jan Fuglesang, Philipp Oster, Lisbeth M. Næss, Oddveig S. Helland, Sandrine Tilman, Einar Rosenqvist, Marianne A. R. Bergsaker, Hanne Nøkleby et Ingeborg S. Aaberge. « Persisting Immune Responses Indicating Long-Term Protection after Booster Dose with Meningococcal Group B Outer Membrane Vesicle Vaccine ». Clinical and Vaccine Immunology 13, n^o 7 (juillet 2006) : 790–96. http://dx.doi.org/10.1128/cvi.00047-06.

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ABSTRACT MenBvac is an outer membrane vesicle vaccine against systemic meningococcal disease caused by serogroup B Neisseria meningitidis. In this placebo-controlled double-blind study including 374 healthy adolescents, the safety and immunogenicity of a schedule of three primary doses 6 weeks apart followed by a fourth dose a year later were evaluated. Antibody responses to the vaccine strain and heterologous strains (non-vaccine-type strains) and the persistence of these antibodies were measured by the serum bactericidal assay (SBA) and enzyme-linked immunosorbent assay up to 1 year after the last dose. The proportion of subjects with SBA titers of ≥4 against the vaccine strain increased from 3% prevaccination to 65% after the third dose. Ten months later, this proportion had declined to 28%. The fourth dose induced a booster response demonstrated by 93% of subjects achieving a titer of ≥4. One year after the booster dose, 64% still showed SBA titers of ≥4. Cross-reacting antibodies were induced against all heterologous strains tested, although the magnitude of SBA titers differed widely between the different strains. All four doses of MenBvac were safe. Both MenBvac and the placebo had reactogenicity profiles of mild to moderate local and systemic reactions. Pain, the most common reaction, was reported with similar frequencies in both groups. No serious adverse events occurred in the MenBvac group. This study confirmed the good immunogenicity of the primary course of MenBvac and demonstrated prolonged persistence and increased cross-reactivity of functional antibodies elicited by a booster dose.

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Sei, Clara J., Nimisha Rikhi, Rachmat Hidajat, Richard F. Schuman, Kevin Muema, Jasmine M. Mutunga, Luke T. Daum et Gerald W. Fischer. « 2752. Peptide Vaccines Utilizing Conserved Hemagglutinin, Neuraminidase, and Matrix Ectodomain Influenza Epitopes Demonstrate Functional Activity Against Group 1 and 2 Influenza Strains ». Open Forum Infectious Diseases 6, Supplement_2 (octobre 2019) : S969—S970. http://dx.doi.org/10.1093/ofid/ofz360.2429.

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Abstract Background Globally, prevention and control of seasonal influenza has faced many challenges in the selection of a vaccine composition that antigenically matches circulating viruses. A universal influenza vaccine approach that targets small conserved influenza virus epitopes/peptides such as the extracellular domain of Matrix 2 (M2e) and induces broadly reactive antibodies may be helpful for both seasonal influenza outbreaks and pandemics. Here we report the ability of two composite peptide vaccines, individually and in combination, to induce broadly reactive antibodies that have binding and functional activity across several contemporary influenza strains in Group 1 and 2. Methods Mice were immunized with peptide composite vaccines against Hemagglutinin (HA), Neuraminidase (NA) and M2e, individually and in combination. Peptide composite vaccines, conjugated to CRM were administered subcutaneously with adjuvant and at least two booster doses. Serum antibody titers were analyzed using an anti-influenza ELISA for binding activity to peptides and live influenza viruses (H3N2 and H1N1) and functional activity was evaluated in vitro using Microneutralization, Hemagglutination Inhibition (HAI), and Antibody-Dependent Cellular Cytotoxicity (ADCC) assays. Results Mice given the peptide composite conjugate vaccines, individually and in combination, had strong humoral responses producing high serum anti-influenza titers post-booster immunization. Anti-influenza serum antibodies demonstrated functional activity against influenza A (H3N2 and H1N1) contemporary strains showing neutralization, HAI and ADCC activity. Conclusion Peptide conjugate vaccines were highly immunogenic in mice. Broadly reactive serum antibodies against the peptides and live influenza viruses were detected. These vaccines individually or in combination, induced antibodies that demonstrated functional activity against contemporary influenza strains in Group 1 and 2 and induced functional anti-influenza monoclonal antibodies. A vaccine that targets one or more HA, NA and M2e influenza epitopes may more closely approach the goal for a true universal influenza vaccine. In vivo protection studies are currently being designed. Disclosures All authors: No reported disclosures.

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