ISOLATION OF TICK-BORNE ENCEPHALITIS-VIRUS FROM IXODES OVATUS (ACARI,IXODIDAE) IN JAPAN

A case of tick-borne encephalitis (TBE) was found in a farming area lo cated in the southern part of Hokkaido, Japan, in 1993. TBE viruses we re isolated from sentinel dogs in the area where the human case occurr ed in 1995. Ticks were collected in the area by 2 collection methods i n 1995 and virus isolation was conducted on ticks in 1995 and 1996. Ix odes ovatus Neumann was found to be the predominant tick species in th e area. In 1996, 2 virus strains were isolated from 600 I. ovatus tick s (300 females and 300 males), giving the minimum infection rate of 0. 33% (2 of 600). The 2 virus strains were identified as TBE virus by an tigenic analysis using monoclonal antibodies and the indirect immunofl uorescent antibody test. The results showed that I. ovatus was a suspe cted vector of the emerging TBE virus in Hokkaido.