Desorption of porcine parvovirus from aluminum hydroxide adjuvant with subsequent viral immunoassay or hemagglutination assay.

Cell culture fluids containing porcine parvovirus were adjuvanted with varying concentrations of aluminum hydroxide gel. Adsorption of virus and total protein to adjuvant was proportional to adjuvant concentration. Desorption of virus and protein from the adjuvant in substantial, reproducible quantities was achieved by washing adjuvanted preparations with 1.2 M potassium phosphate, followed by dialysis and concentration of wash fluids. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of unadjuvanted viral fluids, supernatants of adjuvanted mixtures, and desorptive washings of the corresponding adjuvant pellets revealed no qualitative differences in protein banding patterns. Desorbed virus was quantitated by a hemagglutination assay, or by an enzyme-linked immunoassay employing a monoclonal anti-porcine parvovirus antibody. Virus desorption and subsequent assays permitted in vitro estimation of virus content in adjuvanted porcine parvovirus preparations. This approach may be useful in estimating the antigen content of inactivated aluminum hydroxide adjuvanted veterinary vaccines and reducing the extent of required in vivo testing.