Antigenic characterization among strains of Japanese encephalitis virus isolated in Hyogo Prefecture by the antibody-absorption test.

The immunological characteristics of Japanese encephalitis (JE) virus isolated in Hyogo Prefecture, Japan were investigated by the neutralizing (NT) antibody-absorption and plaque reduction tests. The Nakayama-NIH, JaGAr 01 and Mie 44-1 strains of JE were employed as reference strains. It was confirmed that the JaGAr 01 strain differed immunologically from the Nakayama strain. The new isolates in Hyogo were shown to be different from the JaGAr 01 or Nakayama-NIH, appearing to be intermediates between the two. The antigenicity among the wild strains resembles closely each other. It is to be pointed out that the Nakayama-NIH strain has been the seed virus of JE vaccine currently used in Japan, and the significance of the immunological relation between the Nakayama and newly isolated strains is stressed. The data clearly indicate that the NT antibody-absorption method is useful for antigenic differentiation of JE virus strains.