Antigenic analysis of Japanese encephalitis viruses in Asia by using monoclonal antibodies

Based on our previous study using monoclonal antibodies against three Japanese encephalitis (JE) virus strains, Nakayama-RFVL, Beijing 1 and Kamiyama, 25 JE virus strains isolated mainly in Japan and some from Southeast Asia between 1935 and 1979 fell into five antigenic groups, Nakayama, Beijing 1, Kamiyama, Muar and 691004. In the present study, monoclonal antibodies against Muar and 691004 strains were produced to analyze immunological characteristics of JE virus in detail. We obtained the Muar group-specific antibody and three anti-691004 monoclonal antibodies which showed different reactivities. Furthermore, antigenic comparison of the 22 JE virus strains isolated in Asia between 1963 and 1984 was performed by using the 15 monoclonal antibodies characterized by the different reactivities against the above five antigenic groups. Of these 22 strains, the 17 strains reacted with the Kamiyama group-specific monoclonal antibody, but anti-Nakayama, anti-Beijing 1 and anti-Muar group-specific monoclonal antibodies showed no reactivities with any of the strains. This suggested that the currently prevalent JE virus strains in Asia belonged to the Kamiyama group. The other five strains, ThCMP 1982, KE083, KE093, 733913 and Ling, did not react with the above four group-specific monoclonal antibodies, but all except the KE093 strain showed a similar pattern to the Kamiyama strain on the basis of the reactivities against the other 11 antibodies. The KE093 strain isolated from Thailand in 1983 showed immunologically outstanding difference from other strains.