Comparison of antibody titers determined by hemagglutination inhibition and enzyme immunoassay for JC virus and BK virus

A comparison of antibody titers to JC virus (JCV) or BK virus (BKV) was mad e by hemagglutination inhibition (HI) and enzyme immunoassay (EIA) with 114 human plasma samples. Antibody titers to JCV or BKV determined by HI were lower than those determined by EIA. Nevertheless, as HI titers increased so did EW titers, When antibody data were compared by the Spearman rank corre lation test, highly significant correlations were found between HI and EIA titers, Results obtained by plotting EIA antibody titers for JCV against th ose for BW generally showed a reciprocal relationship, i.e., samples with h igh antibody titers to JCV had lower antibody titers to BKV and vice versa, Some samples, however, had antibody titers to both viruses. Of the samples tested, 25.4% (25 of 114) had HI and EIA antibody titers to JCV and BKV wh ich were identical or closely related. This is not the scenario one would e xpect for cross-reactive epitopes shared by the two viruses, but one sugges ting that these samples were from individuals who had experienced infection s by both viruses. Adsorption with concentrated JCV or BW antigen of sera w ith high antibody titers to both JCV and BKV and testing by JCV and BKV EIA gave results which support this conclusion. Although 52.6% (51 of 97) of t he samples from the Japanese population tested had very high antibody titer s (greater than or equal to 40,960) to either JCV or BW, none of the sample s were found by a dot blot immunoassay to have antibodies which cross-react ed with simian virus 40. The results from this study, in agreement with tho se of others, suggest that humans infected by JCV or BKV produce antibodies to species-specific epitopes on their VP1 capsid protein, which is associa ted with hemagglutination and cellular binding.