Genome Sequence of a Reassortant Strain of Bluetongue Virus

The full genome sequence (19,177 bp) of an Indian strain (IND1988/02) of bluetongue virus (BTV) serotype 23 was determined. This virus was isolated from a sheep that had been killed during a severe bluetongue outbreak that occurred in Rahuri, Maha-rashtra State, western India, in 1988. Phylogenetic analyses of these data demonstrate that most of the genome segments from IND1988/02 belong to the major “eastern ” BTV topotype. However, genome segment 5 belongs to the major “western ” BTV to-potype, demonstrating that IND1988/02 is a reassortant. This may help to explain the increased virulence that was seen during this outbreak in 1988. Genome segment 5 of IND1988/02 shows>99 % sequence identity with some other BTV isolates from In-dia (e.g., BTV-3 IND2003/08), providing further evidence of the existence and circulation of reassortant strains on the subcontinent. Bluetongue virus (BTV) is the type species of the genusOrbivi-rus within the family Reoviridae. There are 26 BTV serotypes that are determined by the specificity of interactions between the virus outer capsid (particularly protein VP2) with neutralizing antibodies generated during infection of the ruminant host (10). The genome of BTV is composed of 10 linear segments of double-stranded RNA (dsRNA) packaged within the three-layered pro-tein capsid (2, 16, 20, 23). The BTV genome codes for a total o