1987 Volume 61 Issue 7 Pages 802-809
Serological study of neutralizing (NT) antibody against Japanese Encephalitis virus was performed in non-affected district of Tokyo. In the group without vaccination, NT antibody was detected in 17 out of 62 sera (27%) below one year of age, 17 out of 87 (20%) in one to two years, and 10 out of 97 (10%) in two to three years. NT positive rate increased gradually up to 46%(6 out of 13 sera), in five to six years of age.
In eight to ten years of age, including vaccine recipients, NT antibody was detected in 23 out of 30 (77%). NT positive rate showed approximately more than 80% over twenties and thirties, declining to 60% in fifties and sixties.
The Kumamoto, JaGAr01, Beijing, and Nakayama-NIH strains of Japanese Encephalitis virus were employed for the comparative serological study. All NT positive sera obtained from children without vaccination revealed a high titer of NT antibody agaisnt Nakayama-NIH strain, and the titer against the Kumamoto strain was the lowest. In most NT positive sera, the NT titers against Nakayama-NIH strain were higher than those against the Beijing strain.
These results demonstrate that Japanese Encephalitis virus is still prevailing even in Tokyo, and that the antigenicity of virus in Tokyo might closely relate to Nakayama-NIH strain.
We should pay attention to a trend of Japanese Encephalitis virus epidemic, considering the recent extent of urbane sanitary conditions.
