Enzyme-linked immunosorbent assay (ELISA) was applied for seroepidemiological study of Japanese encephalitis (JE) using bovine sera. ELISA antibody titers were four fold higher than neutralizing antibody titers. Minimum titer of positive ELISA antibody was set at a serum dilution of 1: 40 to eliminate the non-specific reaction against normal mouse brain components in a test antigen. Antibody prevalence rates against JE virus in Kagoshima, an endemic area, were 26.0% in ELISA and 23.5% in the

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... tralization test. .Meanwhile, sera from Hokkaido, a JE free area, had a prevalence rate of 4.3% by ELISA. Cross-reaction in ELISA between JE and Negishi virus was seen in bovine sera from Kagoshima and also in immune rabbit sera.