We conducted genetic and phylogenetic analyses of genome segment 2 (Seg-2) of bluetongue virus (BTV), which encodes a serotype-specific structural protein of the outer capsid, in samples isolated in Japan between 1985 and 2008. The Japanese strains of BTV clearly sorted into 6 groups by several genetic characteristics of Seg-2, including segment length, open reading frame length, and 5′- and 3′- terminal sequences; these groups were identified as serotypes 2, 3, 9, 12, 16, and 21 by phylogenetic comparison with Seg-2 of reference and field strains of serotypes 1 to 24. Thus, our present study revealed that at least 6 serotypes of BTV were isolated in Japan, suggesting that BTV from several different origins has appeared sporadically in Japan. Our data may be beneficial for understanding BTV epidemiology and for taking better control measures against bluetongue disease in Japan and its neighboring countries in the Asia-Pacific region.
(Subtropical Diseases Research Division)
Shirafuji H. et al. (2012) J. Gen. Virol. 93:1465-1473