Canine parvovirus serum neutralizing antibody assay: assessment of factors responsible for disparity of results between tests.

Canine parvovirus (CPV) serum neutralization (SN) test components were evaluated to determine their effect on antibody titer results. The use of different strains of CPV and different cell substrates had little effect on assay results. Variations in SN antibody titer results were associated with the use of challenge virus preparations that differed in the ratio of hemagglutination units (HAU) to infectivity units (FAID50). Sensitivity and reproducibility can be achieved by using a standardized challenge virus preparation containing a low HAU/FAID50 ratio.