Rapid biotin-avidin method for quantitation of antiviral antibody isotypes

A rapid and efficient method is described for isotype quantitation of antiviral antibodies in mice infected with Theiler's murine encephalomyelitis virus (TMEV). Serum antibodies were reacted with fluorochrome-labeled TMEV in a modified fluid-phase particle concentration fluorescence immunoassay (PCFIA). Biotin and avidin were used to attach antiimmunoglobulin isotype antibodies to polystyrene particles by the separate incubation of biotinylated goat anti-mouse isotypes (IgG1-, IgG2a-, IgG2b-,IgG3-, or IgM-specific) with avidin coupled polystyrene particles. These anti-isotype particles captured the virus-antibody complexes. Mouse myeloma proteins were used to quantitate and standardize isotype profiles of normal mouse serum using fluorescein isothiocyanate (FITC)-labeled, goat anti-mouse isotypes and polystyrene particles coated with goat anti-mouse. These assays quantitated the affinity-purified mouse serum antiviral antibodies for the standardization of antiviral isotype assays. Immunoglobulin of all serum isotypes as well as the amount of virus-specific isotypes can be quantitated rapidly and accurately.