Research from M.D. Raedler and colleagues has provided new data on immunization
2009 JUL 8 - (NewsRx.com) -- "A direct binding Luminex assay has been developed and validated for the detection of human immunoglobulin G (IgG) antibodies to the Staphylococcus aureus iron surface determinant B protein (IsdB) in serum following natural infection or immunization with investigational Saccharomyces cerevisiae-derived IsdB-based vaccines. To ensure that IsdB-specific IgG antibodies are measured following immunization with S. cerevisiae-derived IsdB, an Escherichia coli-produced IsdB antigen is used in the assay," investigators in the United States report. "The IsdB antigen is covalently conjugated to maleimide microspheres via an engineered carboxy-terminal cysteine residue. Antibody titers are determined in a direct binding format, where the phycoerythrin-labeled monoclonal antibody (HP6043) specific for IgG1 to IgG4 binds to human serum IgG antibodies. Fluorescent signal emitted from bound HP6043 is directly proportional to an individual's antibody levels. A pooled human reference serum from vaccinees with high titers to IsdB is used to generate a 12-point standard curve. The correlation of mean fluorescent intensity (MFI) units to mu g/ml of IsdB-specific IgG is made by interpolating the MFI data through a four-parameter curve-fitting algorithm. The assay is sensitive to 1.06 mu g/ml with a dynamic range of 2.1 to 10,625 mu g/ml. The overall specificity of the assay is >96% and the linearity (parallelism) of the assay is -4% per 10-fold dilution. The total precision of the assay was 16.6% relative standard deviation across three different IsdB antigen lots, three different microsphere lots, two secondary antibody lots, and three different operators," wrote M.D. Raedler and colleagues. The researchers concluded: "The assay has proven useful for evaluating the immune response following the administration of different dosages and formulations of investigational IsdB-based vaccines.." Raedler and colleagues published their study in Clinical and Vaccine Immunology (Serologic Assay To Quantify Human Immunoglobulin G Antibodies to the Staphylococcus aureus Iron Surface Determinant B Antigen. Clinical and Vaccine Immunology, 2009;16(5):739-748). For additional information, contact M.D. Raedler, Pharmaceutical Prod Development Vaccines & Biology, Wayne, PA, USA. The publisher of the journal Clinical and Vaccine Immunology can be contacted at: American Society Microbiology, 1752 N St. NW, Washington, DC 20036-2904, USA. Keywords: United States, Wayne, Biotechnology, Cysteine, Dietary Supplement, Escherichia coli, Immunization, Immunology, Medical Device, Monoclonal Antibody, Nutritional Supplement, Vaccines. This article was prepared by Vaccine Weekly editors from staff and other reports. Copyright 2009, Vaccine Weekly via NewsRx.com.
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