Relevant bibliographies by topics / Opsonophagocytic killing assay

Academic literature on the topic 'Opsonophagocytic killing assay'

Author: Grafiati
Published: 9 March 2023
Last updated: 10 March 2023

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Journal articles on the topic "Opsonophagocytic killing assay"

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Lin, J. S., M. K. Park, and M. H. Nahm. "Chromogenic Assay Measuring Opsonophagocytic Killing Capacities of Antipneumococcal Antisera." Clinical Diagnostic Laboratory Immunology 8, no. 3 (May 1, 2001): 528–33. http://dx.doi.org/10.1128/cdli.8.3.528-533.2001.

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ABSTRACT Assays measuring opsonophagocytic killing capacity of immune sera are good surrogate assays for assessing pneumococcal vaccine responses, but they are tedious to perform primarily because the enumeration of surviving bacteria requires the counting of individual bacterial colonies. To overcome this limitation, we have developed a simple and rapid chromogenic assay for estimating the number of surviving bacteria. In this method, the conventional opsonophagocytic killing assays were performed in microtiter wells with differentiated HL-60 cells as phagocytes. At the end of the assay the reaction mixture was cultured for an additional 4.5 h to increase the number of bacteria. After the short culture, XTT (3,3′-[1{(phenylamino)carbonyl}-3,4-tetrazolium]-bis[4-methoxy-6-nitro] benzene sulfonic acid hydrate) and coenzyme Q were added to the wells and the optical density at 450 nm was measured. Our study shows that changes in the optical density were proportional to the number of CFU of live bacteria in the wells. Also, the number of bacteria at the end of the 4.5-h culture was found to be proportional to the original number of bacteria in the wells. When the performance of the chromogenic assay was evaluated by measuring the opsonizing titers ofStreptococcus pneumoniae serotypes 6B and 19F, the sensitivity and precision of the new method were similar to those of the conventional opsonization assay employing the colony counting method. Furthermore, the results of this chromogenic assay obtained with 33 human sera correlate well with those obtained with the conventional colony counting method (R > 0.90) for the two serotypes (6B and 19F). Thus, this simple chromogenic assay would be useful in rapidly measuring the capacities of antisera to opsonize pneumococci.
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Nahm, Moon H., David E. Briles, and Xinhong Yu. "Development of a multi-specificity opsonophagocytic killing assay." Vaccine 18, no. 24 (June 2000): 2768–71. http://dx.doi.org/10.1016/s0264-410x(00)00044-x.

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Nolan, Katrina M., Marie E. Bonhomme, Christina J. Schier, Tina Green, Joseph M. Antonello, and Rocio D. Murphy. "Optimization and validation of a microcolony multiplexed opsonophagocytic killing assay for 15 pneumococcal serotypes." Bioanalysis 12, no. 14 (July 2020): 1003–20. http://dx.doi.org/10.4155/bio-2020-0024.

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Background: To streamline and improve throughput, the agar-based multiplexed opsonophagocytic killing assay (MOPA) was optimized and validated on a microcolony platform for use in the Phase III clinical trial program for V114, an MSD 15-valent pneumococcal conjugate vaccine candidate. Results & methodology: The precision, dilutional linearity and specificity of the microcolony MOPA (mMOPA) were assessed for each serotype in validation experiments. All prespecified acceptance criteria on assay performance were satisfied. Accuracy was assessed by testing 007sp and the US FDA reference panel and comparing to consensus values. The mMOPA produced comparable results to other opsonophagocytic killing assays/MOPAs. Conclusion: The mMOPA is suitable for measuring functional antibodies in adult and pediatric samples. Benefits include throughput, reduced analyst-to-analyst variability and automation potential.
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Hu, Branda T., Xinhong Yu, Thomas R. Jones, Carol Kirch, Sarah Harris, Stephen W. Hildreth, Dace V. Madore, and Sally A. Quataert. "Approach to Validating an Opsonophagocytic Assay for Streptococcus pneumoniae." Clinical Diagnostic Laboratory Immunology 12, no. 2 (February 2005): 287–95. http://dx.doi.org/10.1128/cdli.12.2.287-295.2005.

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ABSTRACT Streptococcus pneumoniae (pneumococcus) polysaccharide serotype-specific antibodies that have opsonophagocytic activity are considered a primary mechanism of host defense against pneumococcal disease. In vitro opsonophagocytic assays (OPAs) with antibody and complement to mediate opsonophagocytic killing of bacteria have been designed and developed as an adjunct to the standardized serum immunoglobulin G antipneumococcal capsular polysaccharide enzyme immunoassay to assess the effectiveness of pneumococcal vaccines. OPA presents challenges for assay standardization and assay precision due to the multiple biologically active and labile components involved in the assay, including human polymorphonuclear leukocytes or cultured effector cells, bacteria, and complement. Control of these biologically labile components is critical for consistent assay performance. An approach to validating the performance of the assay in accordance with International Conference for Harmonization guidelines, including its specificity, intermediate precision, accuracy, linearity, and robustness, is presented. Furthermore, we established parameters for universal reagents and standardization of the use of these reagents to ensure the interlaboratory reproducibility and validation of new methodologies.
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Winter, Linda E., and Stephen J. Barenkamp. "Antibodies Specific for the High-Molecular-Weight Adhesion Proteins of Nontypeable Haemophilus influenzae Are Opsonophagocytic for both Homologous and Heterologous Strains." Clinical and Vaccine Immunology 13, no. 12 (October 4, 2006): 1333–42. http://dx.doi.org/10.1128/cvi.00221-06.

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ABSTRACT The HMW1/HMW2-like adhesion proteins of nontypeable Haemophilus influenzae (NTHI) are expressed by 75% of NTHI strains. Antibodies directed against these proteins are opsonophagocytic in vitro and are protective in an animal model of infection. The objective of the present study was to determine the opsonophagocytic activity of high-titer anti-HMW1/HMW2 immune sera against both homologous and heterologous NTHI strains. Chinchillas were immunized with purified HMW1/HMW2-like proteins from five prototype NTHI strains. Serum opsonophagocytic activity was monitored in an assay that uses a human promyelocytic cell line, HL-60, as the source of phagocytic cells. Preimmune sera did not demonstrate opsonophagocytic killing of any strains. In contrast, the immune sera demonstrated killing of the five homologous NTHI strains at titers ranging from 1:320 to 1:640. The immune sera also demonstrated killing of eight heterologous NTHI strains that express HMW1/HMW2-like proteins at titers ranging from 0 to 1:640. Killing of heterologous strains sometimes demonstrated a prozone phenomenon. None of the immune sera killed NTHI strains that did not express HMW1/HMW2-like proteins. Adsorption of immune sera with HMW1/HMW2-like proteins purified from either homologous or heterologous NTHI strains eliminated opsonophagocytic killing of homologous strains in most cases. These data demonstrate that antibodies produced following immunization with the HMW1/HMW2-like proteins are opsonophagocytic for both homologous and heterologous NTHI and strongly suggest that common epitopes recognized by functionally active antibodies exist on the HMW1/HMW2-like proteins of unrelated NTHI strains. The results argue for the continued investigation of the HMW1/HMW2-like proteins as potential vaccine candidates for the prevention of NTHI disease.
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Ramachandran, Girish, Mary Adetinuke Boyd, Jennifer MacSwords, Ellen E. Higginson, Raphael Simon, James E. Galen, Marcela F. Pasetti, Myron M. Levine, and Sharon M. Tennant. "Opsonophagocytic Assay To Evaluate Immunogenicity of Nontyphoidal Salmonella Vaccines." Clinical and Vaccine Immunology 23, no. 6 (March 30, 2016): 520–23. http://dx.doi.org/10.1128/cvi.00106-16.

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ABSTRACTNontyphoidalSalmonella(NTS) invasive infections are an important cause of morbidity and mortality in sub-Saharan Africa. Several vaccines are in development to prevent these infections. We describe an NTS opsonophagocytic killing assay that uses HL-60 cells and baby rabbit complement to quantify functional antibodies elicited by candidate NTS vaccines.
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Jones, Scott, Nicole J. Moreland, Marta Zancolli, Jeremy Raynes, Jacelyn M. S. Loh, Pierre R. Smeesters, Shiranee Sriskandan, Jonathan R. Carapetis, John D. Fraser, and David Goldblatt. "Development of an opsonophagocytic killing assay for group a streptococcus." Vaccine 36, no. 26 (June 2018): 3756–63. http://dx.doi.org/10.1016/j.vaccine.2018.05.056.

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Choi, Min Joo, Ji Yun Noh, Hee Jin Cheong, Woo Joo Kim, Shun-Mei Lin, Yong Zhi, Jae Hyang Lim, Sangyong Lim, Ho Seong Seo, and Joon Young Song. "Development of a multiplexed opsonophagocytic killing assay (MOPA) for group BStreptococcus." Human Vaccines & Immunotherapeutics 14, no. 1 (October 30, 2017): 67–73. http://dx.doi.org/10.1080/21645515.2017.1377379.

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Wang, D., and S. J. Soong. "Comparisons of titer estimation methods for multiplexed pneumococcal opsonophagocytic killing assay." Computational Statistics & Data Analysis 52, no. 11 (July 2008): 5022–32. http://dx.doi.org/10.1016/j.csda.2008.04.025.

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Kim, Jean O., Sandra Romero-Steiner, Uffe B. Skov Sørensen, Jens Blom, M. Carvalho, S. Barnard, George Carlone, and Jeffrey N. Weiser. "Relationship between Cell Surface Carbohydrates and Intrastrain Variation on Opsonophagocytosis ofStreptococcus pneumoniae." Infection and Immunity 67, no. 5 (May 1, 1999): 2327–33. http://dx.doi.org/10.1128/iai.67.5.2327-2333.1999.

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ABSTRACT Streptococcus pneumoniae undergoes spontaneous phase variation between a transparent and an opaque colony phenotype, the latter being more virulent in a murine model of sepsis. Opaque pneumococci have previously been shown to express lower amounts of C polysaccharide (cell wall teichoic acid) and in this study were shown to have a higher content of capsular polysaccharide by immunoelectron microscopy. This report then examined the relationship between expression of these two cell surface carbohydrate structures and their relative contribution to the increased virulence of opaque variants. Comparison of genetically related strains showed that the differential content of capsular polysaccharide did not affect the amount of teichoic acid as measured by a capture enzyme-linked immunosorbent assay (ELISA). In contrast, when the teichoic acid structure was altered by replacing choline in the growth medium with structural analogs, the quantity of capsular polysaccharide as measured by a capture ELISA was decreased, demonstrating a linkage in the expression of the two surface carbohydrate structures. A standardized assay was used to assess the relative contribution of cell surface carbohydrates to opsonophagocytosis. The opaque variants required 1.2- to 30-fold more immune human serum to achieve 50% opsonophagocytic killing than did related transparent variants (types 6B and 9V). The opsonophagocytic titer was proportional to the quantity of capsular polysaccharide rather than teichoic acid. The major factor in binding of the opsonin, C-reactive protein (CRP), was also the amount of capsular polysaccharide rather than the teichoic acid ligand. Only for the transparent variant (type 6B), which bound more CRP, was there enhanced opsonophagocytic killing in the presence of this serum protein. Increased expression of capsular polysaccharide, therefore, appeared to be the major factor in the decreased opsonophagocytic killing of opaque pneumococci.
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Dissertations / Theses on the topic "Opsonophagocytic killing assay"

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MORASCHINI, LUCA. "Likelihood free and likelihood based approaches to modeling and analysis of functional antibody titers with applications to group B Streptococcus vaccine development." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/76794.

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Opsonophagocytic killing assays (OPKA) are routinely used for the quantification of bactericidal antibodies against Gram-positive bacteria in clinical trial samples. The OPKA readout, the titer, is traditionally estimated using non-linear dose-response regressions as the highest serum dilution yielding a predefined threshold level of bacterial killing. Therefore, these titers depend on a specific killing threshold value and on a specific dose-response model. This thesis describes a novel OPKA titer definition, the threshold free titer, which preserves biological interpretability whilst not depending on any killing threshold. First, a model-free version of this titer is presented and shown to be more precise than the traditional threshold-based titers when using simulated and experimental group B Streptococcus (GBS) OPKA experimental data. Second, a model-based threshold-free titer is introduced to automatically take into account the potential saturation of the OPKA killing curve. The posterior distributions of threshold-based and threshold-free titers is derived for each analysed sample using importance sampling embedded within a Markov chain Monte Carlo sampler of the coefficients of a 4PL logistic dose-response model. The posterior precision of threshold-free titers is again shown to be higher than that of threshold-based titers. The biological interpretability and operational characteristics demonstrated here indicate that threshold-free titers can substantially improve the routine analysis of OPKA experimental and clinical data.
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Book chapters on the topic "Opsonophagocytic killing assay"

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McGregor, Reuben, Scott Jones, Raynes M. Jeremy, David Goldblatt, and Nicole J. Moreland. "An Opsonophagocytic Killing Assay for the Evaluation of Group A Streptococcus Vaccine Antisera." In Methods in Molecular Biology, 323–35. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0467-0_26.

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Wagstaffe, Helen, Scott Jones, Marina Johnson, and David Goldblatt. "Opsonophagocytic Killing Assay to Measure Anti–Group A Streptococcus Antibody Functionality in Human Serum." In Methods in Molecular Biology, 373–86. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1900-1_20.

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