Journal articles on the topic 'RSV - respiratory syncytial virus, memory B cells, antibodies, vaccines'
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Valosky, Janine, Haruka Hishiki, Theoklis E. Zaoutis, and Susan E. Coffin. "Induction of Mucosal B-Cell Memory by Intranasal Immunization of Mice with Respiratory Syncytial Virus." Clinical Diagnostic Laboratory Immunology 12, no. 1 (January 2005): 171–79. http://dx.doi.org/10.1128/cdli.12.1.171-179.2005.
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ABSTRACT The capacity of live or inactivated respiratory syncytial virus (RSV) to induce B-cell memory in respiratory-associated lymphoid tissues of mice was examined. Eight weeks after primary inoculation with either live or inactivated RSV, adult BALB/c mice were challenged with 4 × 105 PFU of RSV. Protection from viral shedding and mucosal production of RSV-specific antibodies were examined at various time points after challenge. We found that primary immunization with live, but not inactivated, RSV induced complete and durable protection upon challenge within the upper and lower respiratory tract. Also, primary immunization with live, but not inactivated, RSV enhanced the production of mucosal RSV-specific immunoglobulin A (IgA) upon challenge. Secondary mucosal IgA responses were characterized by (i) the early production of mucosal IgA by B cells that reside in organized nasal-associated lymphoid tissues, cervical lymph nodes, and bronchial lymph nodes, and (ii) the subsequent production of RSV-specific IgA by mucosal effector tissues, such as the tracheal lamina propria and lung. These findings suggest that primary infection of mice with live RSV might induce mucosal IgA-committed memory B cells. A greater understanding of the characteristics of RSA-specific mucosal memory B cells may facilitate the development of an RSV vaccine.
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Vora, Kalpit, Zhifeng Chen, Hua-Poo Su, Aimin Tang, Kara Cox, Cheryl Callahan, Lan Zhang, et al. "1644. A Potent Broadly Neutralizing Antibody Isolated From Human Memory B-cells Binding to Conserved Site IV on the RSV F Protein." Open Forum Infectious Diseases 5, suppl_1 (November 2018): S47—S48. http://dx.doi.org/10.1093/ofid/ofy209.114.
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Abstract Background Respiratory syncytial virus (RSV) infection is a major public health burden for infants and the elderly worldwide. Currently, there are no approved vaccines and only one moderately effective marketed antibody (Synagis®) for the prevention of RSV infection in high-risk infants. Sampling the human antibody repertoire has led to the realization that the RSV fusion (F) protein in its prefusion conformation is the preferred target for potent neutralizing antibodies and thus makes the protein an attractive candidate for vaccine developers. Methods We report the isolation of a potent and broad RSV neutralizing monoclonal antibody (mAb), which was discovered through molecular cloning of cultured RSV postfusion F protein-baited single-sorted human memory B cells. The epitope for the mAb was mapped to RSV F protein using various methods; including X-ray crystallography, alanine scan, and RSV escape mutant generation Results The mAb binds to both RSV pre- and postfusion F proteins at site IV and can neutralize RSV A and B laboratory strains with subnanomolar potency, superior to that of Palivizumab. Antigenic site IV is conserved between pre- and postfusion F proteins in both RSV A and B subgroups, and sequence alignment showed that the mAb-binding site was conserved in >1,000 RSV A and B clinical isolates. In vivo cotton rat studies demonstrated protection of both the upper and lower respiratory tract of antibody-infused animals challenged with either RSV A or RSV B. Conclusion Overall, the fully human mAb we have isolated has great potential to be developed for passive immune-prophylaxis in infants. A prevalent view of the RSV scientific community is that RSV neutralizing mAbs in human sera primarily target the prefusion F protein and predominantly bind antigenic site Ø. In contrast, our finding demonstrates that very broad and potent RSV neutralizing mAb can also recognize sites common to pre- and postfusion F proteins. Furthermore, the RSV F antigenic site IV presents a neutralizing epitope which is highly conserved. Therefore, it is worthwhile to consider site IV, in addition to site Ø, in the design of RSV subunit vaccines. Disclosures K. Vora, Merck: Employee, Salary. Z. Chen, Merck: Employee, Salary. H. P. Su, Merck: Employee, Salary. A. Tang, Merck: Employee, Salary. K. Cox, merck: Employee, Salary. C. Callahan, Merck: Employee, Salary. L. Zhang, Merck: Employee, Salary. S. Patel, Merck: Employee, Salary. D. Nahas, merck: Employee, Salary. M. Citron, merck: Employee, Salary. P. Cejas, merck: Employee, Salary. R. Swoyer, Merck: Employee, Salary. B. Luo, merck: Employee, Salary. M. Eddins, Merck: Employee, Salary. J. Reid, Merck: Employee, Salary. A. Fridman, Merck: Employee, Salary. J. Galli, Merck: Employee, Salary. S. Cosmi, Merck: Independent Contractor, Salary. G. Dhanasekeran, Merck: Employee, Salary. Z. Wen, Merck: Employee, Salary. X. He, Merck: Employee, Salary. D. Wang, Merck: Employee, Salary. G. Heidecker, Merck: Employee, Salary. J. Flynn, Merck: Employee, Salary. J. Cook, merck: Employee, Salary. S. Soisson, Merck: Employee, Salary. D. Casimiro, Merck: Employee, Salary. A. Bett, Merck: Employee, Salary. W. Blair, Merck: Employee, Salary. D. Distefano, Merck: Employee, Salary. C. Haines, Merck: Employee, Salary.
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Schmidt, Megan E., David K. Meyerholz, and Steven M. Varga. "Pre-existing neutralizing antibodies prevent CD8 T cell-mediated immunopathology following respiratory syncytial virus infection." Mucosal Immunology 13, no. 3 (December 16, 2019): 507–17. http://dx.doi.org/10.1038/s41385-019-0243-4.
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AbstractDespite being a leading cause of severe respiratory disease, there remains no licensed respiratory syncytial virus (RSV) vaccine. Neutralizing antibodies reduce the severity of RSV-associated disease, but are not sufficient for preventing reinfection. In contrast, the role of memory CD8 T cells in protecting against a secondary RSV infection is less established. We recently demonstrated that high-magnitude memory CD8 T cells efficiently reduced lung viral titers following RSV infection, but induced fatal immunopathology that was mediated by IFN-γ. To evaluate the ability of RSV-specific neutralizing antibodies to prevent memory CD8 T cell-mediated immunopathology, mice with high-magnitude memory CD8 T cell responses were treated with neutralizing antibodies prior to RSV challenge. Neutralizing antibody treatment significantly reduced morbidity and prevented mortality following RSV challenge compared with IgG-treated controls. Neutralizing antibody treatment restricted early virus replication, which caused a substantial reduction in memory CD8 T cell activation and IFN-γ production, directly resulting in survival. In contrast, therapeutic neutralizing antibody administration did not impact morbidity, mortality, or IFN-γ levels, despite significantly reducing lung viral titers. Therefore, only pre-existing neutralizing antibodies prevent memory CD8 T cell-mediated immunopathology following RSV infection. Overall, our results have important implications for the development of future RSV vaccines.
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Moffett, Howell F., Carson K. Harms, Kristin S. Fitzpatrick, Marti R. Tooley, Jim Boonyaratanakornkit, and Justin J. Taylor. "B cells engineered to express pathogen-specific antibodies protect against infection." Science Immunology 4, no. 35 (May 17, 2019): eaax0644. http://dx.doi.org/10.1126/sciimmunol.aax0644.
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Effective vaccines inducing lifelong protection against many important infections such as respiratory syncytial virus (RSV), HIV, influenza virus, and Epstein-Barr virus (EBV) are not yet available despite decades of research. As an alternative to a protective vaccine, we developed a genetic engineering strategy in which CRISPR-Cas9 was used to replace endogenously encoded antibodies with antibodies targeting RSV, HIV, influenza virus, or EBV in primary human B cells. The engineered antibodies were expressed efficiently in primary B cells under the control of endogenous regulatory elements, which maintained normal antibody expression and secretion. Using engineered mouse B cells, we demonstrated that a single transfer of B cells engineered to express an antibody against RSV resulted in potent and durable protection against RSV infection in RAG1-deficient mice. This approach offers the opportunity to achieve sterilizing immunity against pathogens for which traditional vaccination has failed to induce or maintain protective antibody responses.
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Muralidharan, Abenaya, Marsha Russell, Louise Larocque, Caroline Gravel, Changgui Li, Wangxue Chen, Terry Cyr, et al. "Targeting CD40 enhances antibody- and CD8-mediated protection against respiratory syncytial virus infection." Journal of Immunology 202, no. 1_Supplement (May 1, 2019): 139.13. http://dx.doi.org/10.4049/jimmunol.202.supp.139.13.
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Abstract Respiratory Syncytial Virus (RSV) infects almost all children under the age of one and is the leading cause of hospitalization among infants. It also causes high rates of infection in the elderly and immunocompromised patient populations. Despite several decades of research with dozens of candidate vaccines being vigorously evaluated in pre-clinical and clinical studies, there is no licensed vaccine available to date. A clinical trial conducted in the early 1960s testing a formaldehyde-inactivated RSV (FIRSV) vaccine resulted in enhanced respiratory disease, following subsequent RSV infection, leading to hospitalization of 80% of the participants and 2 deaths. Since then, other forms of RSV vaccine have also been found to induce enhanced disease in preclinical animal studies. Here, we aimed to develop a vaccine that can effectively protect mice from RSV infection and help identify facets of FIRSV-induced enhanced disease. In this study, BALB/c mice were immunized with an adenoviral vector containing the RSV fusion protein (F) fused with CD40 ligand where the CD40 ligand serves two vital functions as a molecular adjuvant and an antigen-targeting molecule. In contrast to the FIRSV vaccine, the vectored vaccine effectively protected animals against RSV without inducing enhanced respiratory disease. This protection involved a robust induction of neutralizing antibodies and memory CD8 T cells, which were not observed in the FIRSV group. Finally, the vectored vaccine was able to elicit long-lasting protection against RSV, which was mediated by increased levels of effector memory CD8 T cell 3 months post-vaccination.
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Borochova, Kristina, Katarzyna Niespodziana, Katarina Stenberg Hammar, Marianne van Hage, Gunilla Hedlin, Cilla Söderhäll, Margarete Focke-Tejkl, and Rudolf Valenta. "Features of the Human Antibody Response against the Respiratory Syncytial Virus Surface Glycoprotein G." Vaccines 8, no. 2 (June 25, 2020): 337. http://dx.doi.org/10.3390/vaccines8020337.
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Respiratory syncytial virus (RSV) infections are a major cause of serious respiratory disease in infants. RSV occurs as two major subgroups A and B, which mainly differ regarding the surface glycoprotein G. The G protein is important for virus attachment and G-specific antibodies can protect against infection. We expressed the surface-exposed part of A2 strain-derived G (A2-G) in baculovirus-infected insect cells and synthesized overlapping peptides spanning complete A2-G. The investigation of the natural IgG response of adult subjects during a period of one year showed that IgG antibodies (i) recognize G significantly stronger than the fusion protein F0, (ii) target mainly non-conformational, sequential peptide epitopes from the exposed conserved region but also buried peptides, and (iii) exhibit a scattered but constant recognition profile during the observation period. The IgG subclass reactivity profile (IgG1 > IgG2 > IgG4 = IgG3) was indicative of a mixed Th1/Th2 response. Two strongly RSV-neutralizing sera including the 1st WHO standard contained high IgG anti-G levels. G-specific IgG increased strongly in children after wheezing attacks suggesting RSV as trigger factor. Our study shows that RSV G and G-derived peptides are useful for serological diagnosis of RSV-triggered exacerbations of respiratory diseases and underlines the importance of G for development of RSV-neutralizing vaccines.
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Sharma, Anurag, Wenzhu Wu, Biin Sung, Jing Huang, Tiffany Tsao, Xiangming Li, Rika Gomi, Moriya Tsuji, and Stefan Worgall. "Respiratory Syncytial Virus (RSV) Pulmonary Infection in Humanized Mice Induces Human Anti-RSV Immune Responses and Pathology." Journal of Virology 90, no. 10 (March 9, 2016): 5068–74. http://dx.doi.org/10.1128/jvi.00259-16.
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ABSTRACTRespiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease, which causes high rates of morbidity and mortality in infants and the elderly. Models of human RSV pulmonary disease are needed to better understand RSV pathogenesis and to assess the efficacy of RSV vaccines. We assessed the RSV-specific human innate, humoral, and cellular immune responses in humanized mice (mice with a human immune system [HIS mice]) with functional human CD4+T and B cells. These mice were generated by introduction of HLA class II genes, various human cytokines, and human B cell activation factor into immunodeficient NOD scid gamma (NSG) mice by the use of an adeno-associated virus vector, followed by engraftment of human hematopoietic stem cells. During the first 3 days of infection, HIS mice lost more weight and cleared RSV faster than NSG mice. Human chemokine (C-C motif) ligand 3 (CCL3) and human interleukin-1β (IL-1β) expression was detected in the RSV-infected HIS mice. The pathological features induced by RSV infection in HIS mice included peribronchiolar inflammation, neutrophil predominance in the bronchioalveolar lavage fluid, and enhanced airway mucus production. Human anti-RSV IgG and RSV-neutralizing antibodies were detected in serum and human anti-RSV mucosal IgA was detected in bronchioalveolar lavage fluid for up to 6 weeks. RSV infection induced an RSV-specific human gamma interferon response in HIS mouse splenocytes. These results indicate that human immune cells can induce features of RSV lung disease, including mucus hyperplasia, in murine lungs and that HIS mice can be used to elicit human anti-RSV humoral and cellular immunity.IMPORTANCEInfections with respiratory syncytial virus (RSV) are common and can cause severe lung disease in infants and the elderly. The lack of a suitable animal model with disease features similar to those in humans has hampered efforts to predict the efficacy of novel anti-RSV therapies and vaccines for use in humans. A murine model consisting of mice with a human immune system (HIS mice) could be useful for assessment of RSV disease and anti-RSV responses specific to humans. This study investigates an HIS mouse model to imitate human RSV disease and immune responses. We found that RSV lung infection in HIS mice results in an RSV-specific pathology that mimics RSV disease in humans and induces human anti-RSV immune responses. This model could be useful for better understanding of human RSV disease and for the development of RSV therapies.
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Varese, Augusto, Joy Nakawesi, Ana Farias, Freja C. M. Kirsebom, Michelle Paulsen, Rinat Nuriev, and Cecilia Johansson. "Type I interferons and MAVS signaling are necessary for tissue resident memory CD8+ T cell responses to RSV infection." PLOS Pathogens 18, no. 2 (February 2, 2022): e1010272. http://dx.doi.org/10.1371/journal.ppat.1010272.
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Respiratory syncytial virus (RSV) can cause bronchiolitis and viral pneumonia in young children and the elderly. Lack of vaccines and recurrence of RSV infection indicate the difficulty in eliciting protective memory immune responses. Tissue resident memory T cells (TRM) can confer protection from pathogen re-infection and, in human experimental RSV infection, the presence of lung CD8+ TRM cells correlates with a better outcome. However, the requirements for generating and maintaining lung TRM cells during RSV infection are not fully understood. Here, we use mouse models to assess the impact of innate immune response determinants in the generation and subsequent expansion of the TRM cell pool during RSV infection. We show that CD8+ TRM cells expand independently from systemic CD8+ T cells after RSV re-infection. Re-infected MAVS and MyD88/TRIF deficient mice, lacking key components involved in innate immune recognition of RSV and induction of type I interferons (IFN-α/β), display impaired expansion of CD8+ TRM cells and reduction in antigen specific production of granzyme B and IFN-γ. IFN-α treatment of MAVS deficient mice during primary RSV infection restored TRM cell expansion upon re-challenge but failed to recover TRM cell functionality. Our data reveal how innate immunity, including the axis controlling type I IFN induction, instructs and regulates CD8+ TRM cell responses to RSV infection, suggesting possible mechanisms for therapeutic intervention.
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Garg, R., L. Latimer, V. Gerdts, A. Potter, and S. van Drunen Littel-van den Hurk. "Vaccination with the RSV fusion protein formulated with a combination adjuvant induces long-lasting protective immunity." Journal of General Virology 95, no. 5 (May 1, 2014): 1043–54. http://dx.doi.org/10.1099/vir.0.062570-0.
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Respiratory syncytial virus (RSV) is one of the primary causative agents of upper and lower respiratory tract infections in young children, in particular infants. Recently, we reported the protective efficacy of a RSV vaccine formulation consisting of a truncated version of the fusion (F) protein formulated with a Toll-like receptor (TLR) agonist and an immunostimulatory peptide in a carrier system (ΔF/TriAdj). To evaluate the duration of immunity induced by this vaccine candidate, we carried out long-term trials. The ΔF was formulated with triple adjuvant (TriAdj) containing either polyinosinic : polycytidylic acid (polyI : C) or cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODNs) and administered intranasally to mice. One year after the second vaccination all mice were challenged with RSV. Both ΔF/TriAdj formulations mediated the induction of high levels of IgG1, IgG2a and virus-neutralizing antibodies, and IgA in the lungs. Based on the numbers of IFN-γ- and IL-5-secreting cells in the spleen, the immune response was slightly T-helper cell type 1 (Th1)-biased. This was confirmed by the presence of F85–93-specific CD8+ effector T cells in the lungs of both ΔF/TriAdj(polyI : C)- and ΔF/TriAdj(CpG)-immunized mice. Both ΔF/TriAdj formulations induced RSV-specific CD8+ T cells. However, ΔF/TriAdj(polyI : C) generated significantly higher IgG affinity maturation and higher numbers of RSV-specific CD8+ effector memory T cells in lungs and CD8+ central memory T cells in spleen and lymph nodes than ΔF/TriAdj(CpG). After RSV challenge, no virus replication and no evidence of vaccine-induced pathology were detected in mice immunized with either of the ΔF/TriAdj formulations, demonstrating that the duration of immunity induced with these vaccines is at least one year.
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Rostad, Christina A., Christopher C. Stobart, Brian E. Gilbert, Ray J. Pickles, Anne L. Hotard, Jia Meng, Jorge C. G. Blanco, et al. "A Recombinant Respiratory Syncytial Virus Vaccine Candidate Attenuated by a Low-Fusion F Protein Is Immunogenic and Protective against Challenge in Cotton Rats." Journal of Virology 90, no. 16 (June 8, 2016): 7508–18. http://dx.doi.org/10.1128/jvi.00012-16.
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ABSTRACTAlthough respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in infants, a safe and effective vaccine is not yet available. Live-attenuated vaccines (LAVs) are the most advanced vaccine candidates in RSV-naive infants. However, designing an LAV with appropriate attenuation yet sufficient immunogenicity has proven challenging. In this study, we implemented reverse genetics to address these obstacles with a multifaceted LAV design that combined the codon deoptimization of genes for nonstructural proteins NS1 and NS2 (dNS), deletion of the small hydrophobic protein (ΔSH) gene, and replacement of the wild-type fusion (F) protein gene with a low-fusion RSV subgroup B F consensus sequence of the Buenos Aires clade (BAF). This vaccine candidate, RSV-A2-dNS-ΔSH-BAF (DB1), was attenuated in two models of primary human airway epithelial cells and in the upper and lower airways of cotton rats. DB1 was also highly immunogenic in cotton rats and elicited broadly neutralizing antibodies against a diverse panel of recombinant RSV strains. When vaccinated cotton rats were challenged with wild-type RSV A, DB1 reduced viral titers in the upper and lower airways by 3.8 log10total PFU and 2.7 log10PFU/g of tissue, respectively, compared to those in unvaccinated animals (P< 0.0001). DB1 was thus attenuated, highly immunogenic, and protective against RSV challenge in cotton rats. DB1 is the first RSV LAV to incorporate a low-fusion F protein as a strategy to attenuate viral replication and preserve immunogenicity.IMPORTANCERSV is a leading cause of infant hospitalizations and deaths. The development of an effective vaccine for this high-risk population is therefore a public health priority. Although live-attenuated vaccines have been safely administered to RSV-naive infants, strategies to balance vaccine attenuation with immunogenicity have been elusive. In this study, we introduced a novel strategy to attenuate a recombinant RSV vaccine by incorporating a low-fusion, subgroup B F protein in the genetic background of codon-deoptimized nonstructural protein genes and a deleted small hydrophobic protein gene. The resultant vaccine candidate, DB1, was attenuated, highly immunogenic, and protective against RSV challenge in cotton rats.
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Rolsma, Stephanie L., Sandy M. Yoder, Rachel S. Nargi, Eric Brady, Natalia Jimenez-Truque, Isaac Thomsen, Marissa Thompson, et al. "127. Development of a Kinetic ELISA (kELISA) and Reactive B-cell Frequency (RBF) Assay to Detect Respiratory Syncytial Virus (RSV) Pre-Fusion F Protein-Specific Immune Responses in Infants." Open Forum Infectious Diseases 8, Supplement_1 (November 1, 2021): S77—S78. http://dx.doi.org/10.1093/ofid/ofab466.127.
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Abstract Background RSV is a major cause of pediatric respiratory disease. Antibodies to the prefusion conformation of the RSV fusion (pre-F) protein are needed for virus neutralization. Methods We measured RSV-specific responses in two groups of children < 3 years of age; subjects with laboratory-confirmed RSV (RSV-infected) or infants born in the period May to September and enrolled prior to their first RSV season (RSV-uninfected). RSV-infected infants had blood samples obtained at 1, 6, 9, and 12 months after infection. RSV-uninfected infants had blood samples obtained at enrollment, at the end of their first RSV season, and 6 months later. A kELISA to measure RSV pre-F-specific antibodies and an RBF assay to identify RSV F-specific B cells were developed. Results 102 subjects were enrolled; 11 were excluded due to missed visits or withdrawal. Of the 65 subjects in the RSV-uninfected group, all were kELISA positive at enrollment, consistent with maternal antibody transfer. 53 subjects had sufficient samples for analysis at multiple time points; 29 became seronegative and 24 remained seropositive. In the seronegative group, the kELISA value decreased rapidly to < 0.25 by 6 months after the RSV season in 27/29 (93%), (Figure 1a). In the persistently seropositive group, all 24 subjects maintained a positive kELISA value, with some developing higher values over time, consistent with asymptomatic infection (Figure 1b). An RBF assay was used to determine whether antibodies were due to persistent maternal antibodies or endogenous production (Figure 2). In the seronegative group, 24/29 (80%) had a negative RBF; in the seropositive group, 23/24 (96%) had a positive RBF during follow-up. There were 26 subjects in the RSV-infected group; 22 had sufficient samples for analysis at multiple time points. All were seropositive by kELISA at one month post-infection with variable kELISA values during follow-up (Figure 3). 17/22 (77%) had a positive RBF, although 4 of the subjects without a positive RBF had indeterminate results at ≥ 1 visit. Figure 1. kELISA values of baseline RSV-negative subjects, by subject age at time of sample. Panel A: Subjects classified as seronegative (n=29). Panel B: Subjects without known RSV classified as persistently seropositive (n=24). Figure 2. Reactive B-cell frequency assay. The first step in the RBF assay is growth of Lymphoblastoid Cell Lines (LCLs), as shown over days 1-3 (Left-Day 1, Middle-Day 2, Right-Day 3, magnification 200X). The cells circled in the figure indicate a single LCL’s growth over time. LCL supernatant is used to detect RSV F-protein specific antibodies using traditional ELISA, resulting in a positive, indeterminate, or negative result. Indeterminate results occur due to a lack of cell viability and/or failure to form LCLs, resulting in failure to exceed an optical density of 5x background. Figure 3. kELISA values of RSV-infected subjects, by subject age at time of sample. First sample was obtained at approximately one month after laboratory-confirmed RSV. Conclusion Assays measuring F-specific immune responses in infants will be critical for RSV vaccine development. A kELISA targeting RSV pre-F epitopes, with an RBF assay targeting RSV F-specific B cells, may allow discrimination for maternal and infant-derived antibodies. Disclosures Isaac Thomsen, MD, MSCI, Horizon Therapeutics (Individual(s) Involved: Self): Consultant James E. Crowe, Jr., MD, Astra Zeneca (Grant/Research Support)IDBiologics (Board Member, Grant/Research Support, Shareholder)Luna Biologics (Consultant)Meissa Vaccines (Advisor or Review Panel member)Takeda Vaccines (Grant/Research Support) Kathryn M. Edwards, MD, Bionet (Individual(s) Involved: Self): Consultant; CDC (Individual(s) Involved: Self): Research Grant or Support; IBM (Individual(s) Involved: Self): Consultant; Merck (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; Moderna (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; NIH (Individual(s) Involved: Self): Research Grant or Support; Pfizer (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; Roche (Individual(s) Involved: Self): member of DSMB, Other Financial or Material Support; Sanofi Pasteur (Individual(s) Involved: Self): member DSMB, Other Financial or Material Support; Sequiras (Individual(s) Involved: Self): Member DSMB, Other Financial or Material Support; X4 Pharmaceuticals (Individual(s) Involved: Self): Consultant Buddy Creech, MD, MPH, Altimmune (Consultant)Astellas (Other Financial or Material Support, Data and Safety Monitoring Committee)Diotheris (Consultant)GSK (Consultant)Horizon (Consultant)Merck (Scientific Research Study Investigator)Premier Healthcare (Advisor or Review Panel member)Vir (Consultant)
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Patel, Nita, Jing-Hui Tian, Rhonda Flores, Kelsey Jacobson, Michelle Walker, Alyse Portnoff, Mimi Gueber-Xabier, et al. "Flexible RSV Prefusogenic Fusion Glycoprotein Exposes Multiple Neutralizing Epitopes that May Collectively Contribute to Protective Immunity." Vaccines 8, no. 4 (October 14, 2020): 607. http://dx.doi.org/10.3390/vaccines8040607.
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Human respiratory syncytial virus (RSV) is a cause of lower respiratory tract infection in infants, young children, and older adults. There is no licensed vaccine and prophylactic treatment options are limited. The RSV fusion (F) glycoprotein is a target of host immunity and thus a focus for vaccine development. F-trimers are metastable and undergo significant rearrangements from the prefusion to a stable postfusion structure with neutralizing epitopes on intermediate structures. We hypothesize that vaccine strategies that recapitulate the breathable F quaternary structure, and provide accessibility of B-cells to epitopes on intermediate conformations, may collectively contribute to protective immunity, while rigid prefusion F structures restrict access to key protective epitopes. To test this hypothesis, we used the near full-length prefusogenic F as a backbone to construct three prefusion F variants with substitutions in the hydrophobic head cavity: (1) disulfide bond mutant (DS), (2) space filling hydrophobic amino acid substitutions (Cav1), and (3) DS, Cav1 double mutant (DS-Cav1). In this study, we compared the immunogenicity of prefusogenic F to prefusion F variants in two animal models. Native prefusogenic F was significantly more immunogenic, producing high titer antibodies to prefusogenic, prefusion, and postfusion F structures, while animals immunized with DS or DS-Cav1 produced antibodies to prefusion F. Importantly, prefusogenic F elicited antibodies that target neutralizing epitopes including prefusion-specific site zero (Ø) and V and conformation-independent neutralizing sites II and IV. Immunization with DS or DS-Cav1 elicited antibodies primarily to prefusion-specific sites Ø and V with little or no antibodies to other key neutralizing sites. Animals immunized with prefusogenic F also had significantly higher levels of antibodies that cross-neutralized RSV A and B subtypes, while immunization with DS or DS-Cav1 produced antibodies primarily to the A subtype. We conclude that breathable trimeric vaccines that closely mimic the native F-structure, and incorporate strategies for B-cell accessibility to protective epitopes, are important considerations for vaccine design. F structures locked in a single conformation restrict access to neutralizing epitopes that may collectively contribute to destabilizing F-trimers important for broad protection. These results also have implications for vaccine strategies targeting other type 1 integral membrane proteins.
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Vasileiou, Spyridoula, Annie Turney, Manik Kuvalekar, Shivani Mukhi, Ayumi Watanabe, Premal Lulla, Carlos A. Ramos, Juan Vera, Ifigeneia Tzannou, and Ann Leen. "Rapid Generation of Multivirus-Specific T Lymphocytes for the Prevention and Treatment of Respiratory Viral Infections." Blood 132, Supplement 1 (November 29, 2018): 3332. http://dx.doi.org/10.1182/blood-2018-99-113168.
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Abstract Acute upper and lower respiratory tract infections (RTIs) due to community-acquired respiratory viruses (CARVs) including respiratory syncytial virus (RSV), influenza, parainfluenza virus (PIV) and human metapneumovirus (hMPV) are a leading cause of morbidity and mortality worldwide, with individuals whose immune systems are naïve (e.g. children) or compromised being most vulnerable. In allogeneic hematopoietic stem cell transplant (HSCT) recipients, the incidence of CARV-related respiratory viral infection reaches 29%. Most patients initially present with mild symptoms of upper RTI and in 50% of cases the infection progresses to a lower RTI with severe symptoms including bronchiolitis and pneumonia and mortality rates as high as 50%. Currently there are no approved vaccines nor antiviral drugs for hMPV and PIV, while the preventative vaccine for Influenza is not indicated earlier than 6 months post-HSCT. Aerosolized ribavirin is FDA-approved for the treatment of RSV infections, but it is logistically difficult to administer and comes at a considerable cost. Thus, the lack of approved antiviral agents combined with the high cost of antiviral therapy emphasize the need for alternative treatment strategies for CARVs. Our group has previously demonstrated the safety and clinical efficacy of using adoptive T-cell transfer for the treatment of both latent [Epstein-Barr virus (EBV), cytomegalovirus (CMV), BK virus (BKV), human herpesvirus 6 (HHV6)] and lytic [adenovirus (AdV)] viruses in recipients of allo-HSCT by generation of multivirus-specific T cell (VST) lines. Given that susceptibility to CARVs is highly associated with underlying immune deficiency, we wanted to explore the potential for extending this approach to Influenza, RSV, hMPV and PIV3 infections. In order to do so, we exposed PBMCs from healthy donors to a cocktail of pepmixes (overlapping peptide libraries) spanning immunogenic antigens derived from our target viruses [Influenza - NP1 and MP1; RSV - N and F; hMPV - F, N, M2-1 and M; PIV3 - M, HN, N and F] followed by expansion in the presence of activating cytokines in a G-Rex device. Over 10-13 days we achieved an average 8.5 fold expansion [increase from 0.25x107 PBMCs/cm2 to mean 1.9±0.2x107 cells/cm2; n=12). Cells were comprised almost exclusively of CD3+ T cells (96.2±0.6%; mean±SEM), with a mixture of cytotoxic (CD8+) and helper (CD4+) T cells and a phenotype consistent with immediate effector function and long term memory, as evidenced by upregulation of the activation markers CD25, CD69, and CD28 as well as expression of central (CD45RO+/CD62L+) and effector memory markers (CD45RO+/CD62L−), with minimal PD1 or Tim3 expression. Anti-viral specificity of multi-R-VSTs was tested in an IFNγ Elispot assay using each of the individual stimulating antigens as an immunogen and all 12 lines screened proved to be reactive against all 4 of the target viruses [Influenza: mean 735±75.6 SFC/2x105, RSV: 758±69.8, hMPV: 526±100.8, PIV3: 391±93.7]. As demonstrated by intracellular cytokine staining, the immune response was mediated by both CD4+ and CD8+ T cell subsets, and the majority of IFNγ-producing cells also produced TNFα. In addition, the cells secreted GM-CSF as measured by Luminex array, with baseline levels of Th2/suppressive cytokines. Furthermore, upon antigenic stimulation our VSTs produced the effector molecule Granzyme B suggesting the cytolytic potential of these expanded cells, which was confirmed in a standard Cr51-release assay against viral pepmix-loaded autologous PHA blasts. Viral antigen-loaded targets were specifically recognized and lysed by our VSTs, while there was no evidence of activity against non-infected autologous or allogeneic targets. In conclusion, we have shown that it is feasible to rapidly generate a single preparation of polyclonal multi-respiratory (multi-R)-VSTs with specificities directed to Influenza, RSV, hMPV and PIV3 and a total of 12 encoded antigens using GMP-compliant manufacturing methodologies. The expanded cells are Th1-polarized, polyfunctional and selectively able to react to and kill viral antigen-expressing targets with no auto- or alloreactivity, attesting to both their selectivity and their safety for clinical use in HSCT recipients. We anticipate such multi-R-VSTs will provide clinical benefit in preventing or treating CARV infections in the immunocompromised. Disclosures Vera: Viracyte: Equity Ownership. Tzannou:Viracyte: Consultancy, Equity Ownership. Leen:Viracyte: Equity Ownership.
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Nikonova, A. A., I. Y. Isakov, and V. V. Zverev. "IMMUNE RESPONSE TO RESPIRATORY SYNCYTIAL VIRUS INFECTION (ORTHOPNEUMOVIRUS)." Russian Journal of Infection and Immunity, June 26, 2019. http://dx.doi.org/10.15789/2220-7619-irt-1300.
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Respiratory syncytial virus (RSV) infect children as well as elderly and immunocompromised subjects. In 2016, RSV was renamed to Orthopneumovirus owing to virus taxonomy latinization that was included into the family Pneumoviridae. However, in this review we will use old more common name of the respiratory syncytial virus (RSV). RSV can occur throughout human lifetime as it does not induce sterilizing immunity. Diverse immune cell types such as dendritic cells, macrophages, T cells, B cells and eosinophils are involved in the antiviral response during RSV infection. Some of them play an important role in eliminating RSV, while the others can provoke tissue damage. An interaction between these cells occurs through induced cytokines and chemokines, some of them emerged at early disease stages, while the others at later stages. In addition, they can affect course of both primary and secondary RSV infection. Prolonged or persistent RSV infection is observed in children with T cell immunodeficiency, emphasizing importance of T cells in resolution of acute infection and for virus-specific immunological memory development. Virtually all adults and children contain RSV-specific antibodies, but they do not protect from repeated infection. It was shown that high mucosal vs. serum IgG level correlated better with reduced RSV load. A growing body of RSV vaccine candidates has emerged: live-attenuated, protein-based, whole-inactivated, particle-based, subunit antigens, and nucleic acid-based vaccines. While developing vaccines, there should be taken into consideration features of anti-RSV immune response as well as age of subjects to be vaccinated. In particular, to avoid vaccine-associated aggravation of RSV infection it is justified to use live attenuated vaccines in children, whereas middle-aged subjects and the elderly might be applied with subunit vaccines. Currently, no licensed vaccine for RSV infection is available. In this review, we will detail an interaction of the RSV with diverse immune cells as well as on contemporary understanding regarding preventive vaccines in RSV infection.
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Cortjens, B., E. Yasuda, X. Yu, K. Wagner, Y. B. Claassen, A. Q. Bakker, J. B. M. van Woensel, and T. Beaumont. "Broadly Reactive Anti-Respiratory Syncytial Virus G Antibodies from Exposed Individuals Effectively Inhibit Infection of Primary Airway Epithelial Cells." Journal of Virology 91, no. 10 (March 8, 2017). http://dx.doi.org/10.1128/jvi.02357-16.
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ABSTRACT Respiratory syncytial virus (RSV) causes severe respiratory disease in young children. Antibodies specific for the RSV prefusion F protein have guided RSV vaccine research, and in human serum, these antibodies contribute to >90% of the neutralization response; however, detailed insight into the composition of the human B cell repertoire against RSV is still largely unknown. In order to study the B cell repertoire of three healthy donors for specificity against RSV, CD27+ memory B cells were isolated and immortalized using BCL6 and Bcl-xL. Of the circulating memory B cells, 0.35% recognized RSV-A2-infected cells, of which 59% were IgA-expressing cells and 41% were IgG-expressing cells. When we generated monoclonal B cells selected for high binding to RSV-infected cells, 44.5% of IgG-expressing B cells and 56% of IgA-expressing B cells reacted to the F protein, while, unexpectedly, 41.5% of IgG-expressing B cells and 44% of IgA expressing B cells reacted to the G protein. Analysis of the G-specific antibodies revealed that 4 different domains on the G protein were recognized. These epitopes predicted cross-reactivity between RSV strain A (RSV-A) and RSV-B and matched the potency of antibodies to neutralize RSV in HEp-2 cells and in primary epithelial cell cultures. G-specific antibodies were also able to induce antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis of RSV-A2-infected cells. However, these processes did not seem to depend on a specific epitope. In conclusion, healthy adults harbor a diverse repertoire of RSV glycoprotein-specific antibodies with a broad range of effector functions that likely play an important role in antiviral immunity. IMPORTANCE Human RSV remains the most common cause of severe lower respiratory tract disease in premature babies, young infants, the elderly, and immunocompromised patients and plays an important role in asthma exacerbations. In developing countries, RSV lower respiratory tract disease has a high mortality. Without an effective vaccine, only passive immunization with palivizumab is approved for prophylactic treatment. However, highly potent RSV-specific monoclonal antibodies could potentially serve as a therapeutic treatment and contribute to disease control and mortality reduction. In addition, these antibodies could guide further vaccine development. In this study, we isolated and characterized several novel antibodies directed at the RSV G protein. This information can add to our understanding and treatment of RSV disease.
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McGinnes Cullen, Lori, Madelyn R. Schmidt, and Trudy G. Morrison. "Effect of Previous Respiratory Syncytial Virus Infection on Murine Immune Responses to F and G Protein-Containing Virus-Like Particles." Journal of Virology 93, no. 9 (February 13, 2019). http://dx.doi.org/10.1128/jvi.00087-19.
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ABSTRACTMost individuals are infected with respiratory syncytial virus (RSV) by age two, but infection does not result in long-term protective immunity to subsequent infections. Previous RSV infection may, however, impact responses to an RSV vaccine. The goal of these studies was to explore the effect of previous RSV infection on murine antibody responses to RSV F and G protein-containing virus-like particles (VLP), comparing responses to those resulting from VLP immunization of RSV-naive animals. These studies showed that after RSV infection, immunization with a single dose of VLPs containing a conformation-stabilized prefusion F protein stimulated high titers of neutralizing antibodies (NA), while an immunization with post-F-containing VLPs or a second RSV infection only weakly stimulated NA, even though total anti-F protein IgG antibody levels in both VLP-immunized animals were similar. Furthermore, single pre-F or post-F VLP immunization of animals previously infected (primed) with RSV resulted in total anti-F antibody titers that were 10- to 12-fold higher than titers after a VLP prime and boost of RSV-naive animals or after two consecutive RSV infections. The avidities of serum antibodies as well as numbers of splenic B cells and bone marrow cells after different immunization protocols were also assessed. The combined results show that RSV infection can quite effectively prime animals for the production of protective antibodies that can be efficiently activated by a pre-F VLP boost but not by a post-F VLP boost or a second RSV infection.IMPORTANCEHumans may experience repeated infections caused by the same serotype of respiratory syncytial virus (RSV), in contrast to infections with most other viruses, indicating that immune memory responses to RSV are defective. However, the effects of any residual but nonprotective immunity on responses to RSV vaccines are not clear. This study demonstrates that a VLP vaccine candidate containing a stabilized prefusion F protein can robustly stimulate protective immunity in animals previously infected with RSV, while a second RSV infection or a postfusion F-containing VLP cannot. This result shows that a properly constructed immunogen can be an effective vaccine in animals previously infected with RSV. The results also suggest that the defect in RSV memory is not in the induction of that memory but rather in its activation by a subsequent RSV infection.
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Chang, Lauren A., Emily Phung, Michelle C. Crank, Kaitlyn M. Morabito, Tonya Villafana, Filip Dubovsky, Judith Falloon, et al. "A prefusion-stabilized RSV F subunit vaccine elicits B cell responses with greater breadth and potency than a postfusion F vaccine." Science Translational Medicine 14, no. 676 (December 21, 2022). http://dx.doi.org/10.1126/scitranslmed.ade0424.
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There is currently no licensed vaccine for respiratory syncytial virus (RSV). Here, we assess the effect of RSV fusion protein (F) conformation on B cell responses in a post hoc comparison of samples from the DS-Cav1 [prefusion (pre-F)] and MEDI7510 [postfusion (post-F)] vaccine clinical trials. We compared the magnitude and quality of the serological and B cell responses across time points and vaccines. We measured RSV A and B neutralization, F-binding immunoglobulin G titers, and competition assays at week 0 (before vaccination) and week 4 (after vaccination) to evaluate antibody specificity and potency. To compare B cell specificity and activation, we used pre-F and post-F probes in tandem with a 17-color immunophenotyping flow cytometry panel at week 0 (before vaccination) and week 1 (after vaccination). Our data demonstrate that both DS-Cav1 and MEDI7510 vaccination robustly elicit F-specific antibodies and B cells, but DS-Cav1 elicited antibodies that more potently neutralized both RSV A and B. The superior potency was mediated by antibodies that bind antigenic sites on the apex of pre-F that are not present on post-F. In the memory (CD27 + ) B cell compartment, vaccination with DS-Cav1 or MEDI7510 elicited B cells with different epitope specificities. B cells preferentially binding the pre-F probe were activated in DS-Cav1–vaccinated participants but not in MEDI7510-vaccinated participants. Our findings emphasize the importance of using pre-F as an immunogen in humans because of its deterministic role in eliciting highly potent neutralizing antibodies and memory B cells.
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Xiao, Xiao, Arthur Fridman, Lu Zhang, Pavlo Pristatsky, Eberhard Durr, Michael Minnier, Aimin Tang, et al. "Profiling of hMPV F-specific antibodies isolated from human memory B cells." Nature Communications 13, no. 1 (May 10, 2022). http://dx.doi.org/10.1038/s41467-022-30205-x.
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AbstractHuman metapneumovirus (hMPV) belongs to the Pneumoviridae family and is closely related to respiratory syncytial virus (RSV). The surface fusion (F) glycoprotein mediates viral fusion and is the primary target of neutralizing antibodies against hMPV. Here we report 113 hMPV-F specific monoclonal antibodies (mAbs) isolated from memory B cells of human donors. We characterize the antibodies’ germline usage, epitopes, neutralization potencies, and binding specificities. We find that unlike RSV-F specific mAbs, antibody responses to hMPV F are less dominant against the apex of the antigen, and the majority of the potent neutralizing mAbs recognize epitopes on the side of hMPV F. Furthermore, neutralizing epitopes that differ from previously defined antigenic sites on RSV F are identified, and multiple binding modes of site V and II mAbs are discovered. Interestingly, mAbs that bind preferentially to the unprocessed prefusion F show poor neutralization potency. These results elucidate the immune recognition of hMPV infection and provide novel insights for future hMPV antibody and vaccine development.
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Blunck, Brittani N., Laura S. Angelo, David Henke, Vasanthi Avadhanula, Matthew Cusick, Laura Ferlic-Stark, Lynn Zechiedrich, Brian E. Gilbert, and Pedro A. Piedra. "Adult Memory T Cell Responses to the Respiratory Syncytial Virus Fusion Protein During a Single RSV Season (2018–2019)." Frontiers in Immunology 13 (March 29, 2022). http://dx.doi.org/10.3389/fimmu.2022.823652.
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Respiratory Syncytial Virus (RSV) is ubiquitous and re-infection with both subtypes (RSV/A and RSV/B) is common. The fusion (F) protein of RSV is antigenically conserved, induces neutralizing antibodies, and is a primary target of vaccine development. Insight into the breadth and durability of RSV-specific adaptive immune response, particularly to the F protein, may shed light on susceptibility to re-infection. We prospectively enrolled healthy adult subjects (n = 19) and collected serum and peripheral blood mononuclear cells (PBMCs) during the 2018–2019 RSV season. Previously, we described their RSV-specific antibody responses and identified three distinct antibody kinetic profiles associated with infection status: uninfected (n = 12), acutely infected (n = 4), and recently infected (n = 3). In this study, we measured the longevity of RSV-specific memory T cell responses to the F protein following natural RSV infection. We stimulated PBMCs with overlapping 15-mer peptide libraries spanning the F protein derived from either RSV/A or RSV/B and found that memory T cell responses mimic the antibody responses for all three groups. The uninfected group had stable, robust memory T cell responses and polyfunctionality. The acutely infected group had reduced polyfunctionality of memory T cell response at enrollment compared to the uninfected group, but these returned to comparable levels by end-of-season. The recently infected group, who were unable to maintain high levels of RSV-specific antibody following infection, similarly had decreased memory T cell responses and polyfunctionality during the RSV season. We observed subtype-specific differences in memory T cell responses and polyfunctionality, with RSV/A stimulating stronger memory T cell responses with higher polyfunctionality even though RSV/B was the dominant subtype in circulation. A subset of individuals demonstrated an overall deficiency in the generation of a durable RSV-specific adaptive immune response. Because memory T cell polyfunctionality may be associated with protection against re-infection, this latter group would likely be at greater risk of re-infection. Overall, these results expand our understanding of the longevity of the adaptive immune response to the RSV fusion protein and should be considered in future vaccine development efforts.
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Phung, Emily, Lauren A. Chang, Maryam Mukhamedova, Lijuan Yang, Deepika Nair, Scott A. Rush, Kaitlyn M. Morabito, et al. "Elicitation of pneumovirus-specific B cell responses by a prefusion-stabilized respiratory syncytial virus F subunit vaccine." Science Translational Medicine 14, no. 650 (June 22, 2022). http://dx.doi.org/10.1126/scitranslmed.abo5032.
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Respiratory syncytial virus (RSV) is a substantial cause of morbidity and mortality globally. A candidate RSV prefusion (pre-F)–stabilized subunit vaccine, DS-Cav1, has previously been shown to elicit potent and durable neutralizing activity in a phase 1 clinical trial in healthy adults. Here, we used fluorescently labeled probes and flow cytometry to evaluate the antigen specificity and phenotype of RSV F–specific B cells longitudinally after DS-Cav1 immunization. Peripheral blood mononuclear cells (PBMCs) collected at time points before the first immunization through the end of the trial at 44 weeks were assessed by flow cytometry. Our data demonstrate a rapid increase in the frequency of pre-F–specific IgG + and IgA + B cells after the first immunization and a modest increase after a second immunization at week 12. Nearly all F-specific B cells down-regulated CD21 and up-regulated the proliferation marker CD71 after the first immunization, with less pronounced activation after the second immunization. Memory B cells (CD27 + CD21 + ) specific for pre-F remained elevated above baseline at 44 weeks after vaccination. DS-Cav1 vaccination also activated human metapneumovirus (HMPV) cross-reactive B cells capable of binding prefusion-stabilized HMPV F protein and increased HMPV F-binding antibodies and neutralizing activity for HMPV in some participants. In summary, vaccination with RSV pre-F resulted in the expansion and activation of RSV and HMPV F-specific B cells that were maintained above baseline for at least 10 months and could contribute to long-term pneumovirus immunity.
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Jenkins, Tiffany, Rongzhang Wang, Olivia Harder, Miaoge Xue, Phylip Chen, Jacqueline Corry, Christopher Walker, et al. "A novel live attenuated RSV vaccine candidate with mutations in the L protein SAM binding site and the G protein cleavage site is protective in cotton rats and a rhesus macaque." Journal of Virology, November 11, 2020. http://dx.doi.org/10.1128/jvi.01568-20.
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Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in children < 5 years of age worldwide, infecting the majority of infants in their first year of life. Despite the widespread impact of this virus, no vaccine is currently available. For over 50 years, live attenuated vaccines (LAV) have been shown to protect against other childhood viral infections, offering the advantage of presenting all viral proteins to the immune system for stimulation of both B and T cell responses and memory. The RSV LAV candidate described here, rgRSV-L(G1857A)-G(L208A), contains two modifications: an attenuating mutation in the S-adenosylmethionine (SAM) binding site of the viral mRNA cap methyltransferase (MTase) within the large (L) polymerase protein and a mutation in the attachment (G) glycoprotein that inhibits its cleavage during production in Vero cells, resulting in virus with a “non-cleaved G” (ncG). RSV virions containing the ncG have an increased ability to infect primary well-differentiated human bronchial epithelial (HBE) cultures which model the in vivo site of immunization, the ciliated airway epithelium. This RSV LAV candidate is produced efficiently in Vero cells, is highly attenuated in HBE cultures, efficiently induces neutralizing antibodies that are long-lasting, and provides protection against an RSV challenge in the cotton rat, without causing enhanced disease. Similar results were obtained in a rhesus macaque. Importance Globally, RSV is a major cause of death in children under one year of age, yet no vaccine is available. We have generated a novel RSV live attenuated vaccine candidate containing mutations in the L and G proteins. The L polymerase mutation does not inhibit virus yield in Vero cells, the cell type required for vaccine production, but greatly reduces virus spread in HBE cultures, a logical in vitro predictor of in vivo attenuation. The G attachment protein mutation reduces its cleavage in Vero cells, thereby increasing vaccine virus yield, making vaccine production more economical. In cotton rats, this RSV vaccine candidate is highly attenuated at a dose of 105 PFU and completely protective following immunization with 500 PFU, 200-fold less than the dose usually used in such studies. It also induced long-lasting antibodies in cotton rats and protected a rhesus macaque from RSV challenge. This mutant virus is an excellent RSV live attenuated vaccine candidate.
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Huang, Jiachen, Rose J. Miller, and Jarrod J. Mousa. "A Pan-Pneumovirus vaccine based on immunodominant epitopes of the fusion protein." Frontiers in Immunology 13 (August 8, 2022). http://dx.doi.org/10.3389/fimmu.2022.941865.
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Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two leading causes of severe respiratory infections in children, the elderly, and immunocompromised patients. The fusion (F) protein is the major target of neutralizing antibodies. Recent developments in stabilizing the pre-fusion conformation of the F proteins, and identifying immunodominant epitopes that elicit potent neutralizing antibodies have led to the testing of numerous pre-fusion RSV F-based vaccines in clinical trials. We designed and tested the immunogenicity and protective efficacy of a chimeric fusion protein that contains immunodominant epitopes of RSV F and hMPV F (RHMS-1). RHMS-1 has several advantages over vaccination with pre-fusion RSV F or hMPV F, including a focus on recalling B cells to the most important protective epitopes and the ability to induce protection against two viruses with a single antigen. RHMS-1 was generated as a trimeric recombinant protein, and analysis by negative-stain electron microscopy demonstrated the protein resembles the pre-fusion conformation. Probing of RHMS-1 antigenicity using a panel of RSV and hMPV F-specific monoclonal antibodies (mAbs) revealed the protein retains features of both viruses, including the pre-fusion site Ø epitope of RSV F. Mice immunized with RHMS-1 generated neutralizing antibodies to both viruses and were completely protected from RSV or hMPV challenge. Overall, this study demonstrates protection against two viruses with a single antigen and supports testing of RHMS-1 in additional pre-clinical animal models.
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Maier, Clara, Jana Fuchs, Pascal Irrgang, Michael Hermann Wißing, Jasmin Beyerlein, Matthias Tenbusch, and Dennis Lapuente. "Mucosal immunization with an adenoviral vector vaccine confers superior protection against RSV compared to natural immunity." Frontiers in Immunology 13 (July 28, 2022). http://dx.doi.org/10.3389/fimmu.2022.920256.
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Respiratory syncytial virus (RSV) infections are the leading cause of severe respiratory illness in early infancy. Although the majority of children and adults mount immune responses against RSV, recurrent infections are frequent throughout life. Humoral and cellular responses contribute to an effective immunity but also their localization at respiratory mucosae is increasingly recognized as an important factor. In the present study, we evaluate a mucosal vaccine based on an adenoviral vector encoding for the RSV fusion protein (Ad-F), and we investigate two genetic adjuvant candidates that encode for Interleukin (IL)-1β and IFN-β promoter stimulator I (IPS-1), respectively. While vaccination with Ad-F alone was immunogenic, the inclusion of Ad-IL-1β increased F-specific mucosal immunoglobulin A (IgA) and tissue-resident memory T cells (TRM). Consequently, immunization with Ad-F led to some control of virus replication upon RSV infection, but Ad-F+Ad-IL-1β was the most effective vaccine strategy in limiting viral load and weight loss. Subsequently, we compared the Ad-F+Ad-IL-1β-induced immunity with that provoked by a primary RSV infection. Systemic F-specific antibody responses were higher in immunized than in previously infected mice. However, the primary infection provoked glycoprotein G-specific antibodies as well eventually leading to similar neutralization titers in both groups. In contrast, mucosal antibody levels were low after infection, whereas mucosal immunization raised robust F-specific responses including IgA. Similarly, vaccination generated F-specific TRM more efficiently compared to a primary RSV infection. Although the primary infection resulted in matrix protein 2 (M2)-specific T cells as well, they did not reach levels of F-specific immunity in the vaccinated group. Moreover, the infection-induced T cell response was less biased towards TRM compared to vaccine-induced immunity. Finally, our vaccine candidate provided superior protection against RSV infection compared to a primary infection as indicated by reduced weight loss, virus replication, and tissue damage. In conclusion, our mucosal vaccine candidate Ad-F+Ad-IL-1β elicits stronger mucosal immune responses and a more effective protection against RSV infection than natural immunity generated by a previous infection. Harnessing mucosal immune responses by next-generation vaccines is therefore a promising option to establish effective RSV immunity and thereby tackle a major cause of infant hospitalization.
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Migueles, Stephen A., Daniel C. Rogan, Noah V. Gavil, Elizabeth P. Kelly, Sushila A. Toulmin, Lawrence T. Wang, Justin Lack, et al. "Antigenic Restimulation of Virus-Specific Memory CD8+ T Cells Requires Days of Lytic Protein Accumulation for Maximal Cytotoxic Capacity." Journal of Virology 94, no. 23 (September 9, 2020). http://dx.doi.org/10.1128/jvi.01595-20.
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ABSTRACT In various infections or vaccinations of mice or humans, reports of the persistence and the requirements for restimulation of the cytotoxic mediators granzyme B (GrB) and perforin (PRF) in CD8+ T cells have yielded disparate results. In this study, we examined the kinetics of PRF and GrB mRNA and protein expression after stimulation and associated changes in cytotoxic capacity in virus-specific memory cells in detail. In patients with controlled HIV or cleared respiratory syncytial virus (RSV) or influenza virus infections, all virus-specific CD8+ T cells expressed low PRF levels without restimulation. Following stimulation, they displayed similarly delayed kinetics for lytic protein expression, with significant increases occurring by days 1 to 3 before peaking on days 4 to 6. These increases were strongly correlated with, but were not dependent upon, proliferation. Incremental changes in PRF and GrB percent expression and mean fluorescence intensity (MFI) were highly correlated with increases in HIV-specific cytotoxicity. mRNA levels in HIV-specific CD8+ T-cells exhibited delayed kinetics after stimulation as with protein expression, peaking on day 5. In contrast to GrB, PRF mRNA transcripts were little changed over 5 days of stimulation (94-fold versus 2.8-fold, respectively), consistent with posttranscriptional regulation. Changes in expression of some microRNAs, including miR-17, miR-150, and miR-155, suggested that microRNAs might play a significant role in regulation of PRF expression. Therefore, under conditions of extremely low or absent antigen levels, memory virus-specific CD8+ T cells require prolonged stimulation over days to achieve maximal lytic protein expression and cytotoxic capacity. IMPORTANCE Antigen-specific CD8+ T cells play a major role in controlling most virus infections, primarily by perforin (PRF)- and granzyme B (GrB)-mediated apoptosis. There is considerable controversy regarding whether PRF is constitutively expressed, rapidly increased similarly to a cytokine, or delayed in its expression with more prolonged stimulation in virus-specific memory CD8+ T cells. In this study, the degree of cytotoxic capacity of virus-specific memory CD8+ T cells was directly proportional to the content of lytic molecules, which required antigenic stimulation over several days for maximal levels. This appeared to be modulated by increases in GrB transcription and microRNA-mediated posttranscriptional regulation of PRF expression. Clarifying the requirements for maximal cytotoxic capacity is critical to understanding how viral clearance might be mediated by memory cells and what functions should be induced by vaccines and immunotherapies.
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Raj, Gerard, Rekha Priyadarshini, Sakthibalan Murugesan, and Mangaiarkkarasi Adhimoolam. "Monoclonal antibodies against infectious microbes: so long and too little!" Infectious Disorders - Drug Targets 20 (March 12, 2020). http://dx.doi.org/10.2174/1871526520666200312154649.
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Monoclonal antibodies (mAbs) as alternatives or more often as complementary to the conventional antimicrobials are being developed for the management of infectious conditions for the past two decades. These pharmacotherapeutic strategies are inevitable as the burden of antimicrobial resistance is far-reaching in recent times. MAbs are part of the targeted pharmacotherapy armamentarium with high degree of specificity – hence, exert comparatively superior efficacy and tolerability than the conventional polyclonal antisera. So far, only five mAbs have been approved for the management of infectious states – since, the marketing authorization (1998) given to palivizumab (Synagis®) for the prophylaxis of lower respiratory tract disease caused by respiratory syncytial virus in pediatric patients. Ibalizumab-uiyk (Trogarzo™) used for the management of multidrug resistant HIV-1 infection not yielding to at least 10 antiretroviral drugs previously was approved recently. Among the three antibacterial mAbs, raxibacumab (ABthrax®/ Anthrin®) and obiltoxaximab (Anthim®) are indicated for the treatment and prophylaxis of inhalation anthrax due to Bacillus anthracis; bezlotoxumab (Zinplava®) is used to reduce the recurrence of Clostridium difficile infection. There are also around 30 and 15 mAbs in different phases of development for viral and bacterial conditions. As alternatives to the traditional antivirals and antibacterials, the antimicrobial mAbs are the need of the hour. These mAbs are more relevant in the management of conditions like emerging viral outbreaks wherein there is a lack of prophylactic vaccines. The current cutting-edge engineering technologies revolutionizing the production of mAbs include phage-displayed antibody libraries, cloning from single-memory B cells or single-antibody-secreting plasma B cells, proteomics-directed cloning of mAbs from serum clubbed with high-throughput sequencing techniques. Yet, the cost of manufacture continues to be the main limiting factor.