Development of an alternative method for neutralization test of Japanese encephalitis virus using pig sera in national epidemiological surveillance program in Japan

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We previously reported that the cytopathic effect (CPE) and single-round infectious particles (SRIPs) assays are useful alternatives to the focus-forming assay method for testing human Japanese encephalitis virus (JEV) susceptibility. In this study, we investigated whether these alternative methods were useful for testing JEV antibodies in pig sera in the same survey. A total of 240 serum samples from 6-month-old pigs were used in this study. Antibody titers were evaluated using four methods: the hemagglutination inhibition (HI) assay, currently used for pig serum in the national epidemiological surveillance program for vaccine-preventable diseases in Japan; the focus-forming assay, which is currently used for human serum; and the CPE and SRIPs assays, both previously evaluated using human serum. Unfortunately, the antibody titers in the HI assay showed almost no correlation with those of other methods. However, if the presence or absence of antibodies is determined instead of titer, using each assay method, a concordance rate > 90% was observed for all combinations of assay methods. Among the evaluated assays, the SRIPs assay showed excellent agreement with conventional neutralization assays and may serve as a practical alternative for evaluating JEV neutralizing antibodies in pigs.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.