Phylogenetic Characterization Genome Segment 2 of Bluetongue Virus Strains Belonging to Serotypes 5, 7 and 24 Isolated for the First Time in China During 2012 to 2014.

Bluetongue is endemic in China, and Bluetongue virus (BTV) strains belonging to eight different serotypes (BTV-1, BTV-2, BTV-3, BTV-4, BTV-9, BTV-12, BTV-15 and BTV-16) had been isolated between 1996 and 1997. However, there has been a long pause in investigating the epidemiology of BTV infection since then. During 2012-2014, eight BTV strains belonging to serotypes 5, 7 and 24 were isolated for the first time in Yunnan and Guangdong provinces from the blood of sentinel animals. Phylogenetic analyses of genome segment 2 of these Chinese BTV strains grouped them into nucleotypes E, F and A, respectively, along with the reference strains of the same serotype. For each serotype, Chinese strains cluster together closely to form a China's sublineage. In addition, these strains were most closely related to strains from Africa, indicating that they may share a recent common ancestry with African strains. To our knowledge, this is the first time that BTV-5, BTV-7 and BTV-24 strains have been isolated in South-East Asia. These data will be beneficial for understanding the BTV epidemiology and improving diagnostic assays and control measures against bluetongue in China and its neighbouring countries in the Asia-Pacific region.