title: Surface plasmon resonance measurements of plasma antibody avidity during primary and secondary responses to anthrax protective antigen.
abstract: Establishment of humoral immunity against pathogens is dependent on events that occur in the germinal center and the subsequent induction of high-affinity neutralizing antibodies. Quantitative assays that allow monitoring of affinity maturation and duration of antibody responses can provide useful information regarding the efficacy of vaccines and adjuvants. Using an anthrax protective antigen (rPA) and alum model antigen/adjuvant system, we describe a methodology for monitoring antigen-specific serum antibody concentration and avidity by surface plasmon resonance during primary and secondary immune responses. Our analyses showed that following a priming dose in mice, rPA-specific antibody concentration and avidity increases over time and reaches a maximal response in about six weeks, but gradually declines in the absence of antigenic boost. Germinal center reactions were observed early with maximal development achieved during the primary response, which coincided with peak antibody avidity responses to primary immunization. Boosting with antigen resulted in a rapid increase in rPA-specific antibody concentration and five-fold increase in avidity, which was not dependent on sustained GC development. The described methodology couples surface plasmon resonance-based plasma avidity measurements with germinal center analysis and provides a novel way to monitor humoral responses that can play a role in facilitating vaccine and adjuvant development.
authors: Duke Human Vaccine Institute and Departments of Medicine, Duke University Medical Center, Durham, NC 27710, United States.
authors: Heather E
authors: HE
authors: Lynch
authors: Duke Human Vaccine Institute and Departments of Medicine, Duke University Medical Center, Durham, NC 27710, United States.
authors: Shelley M
authors: SM
authors: Stewart
authors: Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, United States.
authors: Thomas B
authors: TB
authors: Kepler
authors: Duke Human Vaccine Institute and Departments of Medicine, Duke University Medical Center, Durham, NC 27710, United States.
authors: Gregory D
authors: GD
authors: Sempowski
authors: Duke Human Vaccine Institute and Departments of Medicine, Duke University Medical Center, Durham, NC 27710, United States. Electronic address: alam0004@mc.duke.edu.
authors: S Munir
authors: SM
authors: Alam
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000534:Alum Compounds / Q000008:administration & dosage; D000818:Animals; D000881:Anthrax / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D022122:Anthrax Vaccines / Q000008:administration & dosage / Q000276:immunology*; D000907:Antibodies, Bacterial / Q000097:blood*; D057134:Antibodies, Neutralizing / Q000097:blood*; D000915:Antibody Affinity; D000918:Antibody Specificity; D000942:Antigens, Bacterial / Q000276:immunology; D001408:Bacillus anthracis / Q000276:immunology* / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors* / Q000276:immunology; D005260:Female; D018858:Germinal Center; D056724:Immunity, Humoral; D007117:Immunization, Secondary; D051379:Mice; D008810:Mice, Inbred C57BL; D020349:Surface Plasmon Resonance
chemical_list: D000276:Adjuvants, Immunologic; D000534:Alum Compounds; D022122:Anthrax Vaccines; D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin; C041524:aluminum sulfate
keywords: Antibody avidity; Germinal centers; Protective antigen (PA); Surface plasmon resonance (SPR)