RAPID COMMUNICATION Sequences of Genes Encoding Type-Specific and Group- Specific Antigens of an Indian Isolate of Bluetongue Virus Serotype 10 (BTV-10) and Implications for their Origin S. R. K. Gollapalli 1 , S. Mallavarapu 2 , M. Uma 2 , P. P. Rao 1,2 , B. Susmitha 1 , P. U. V. S. Prasad 1 , P. Chaitanya 1 , G. Prasad 3 , N. R. Hegde 2 and Y. N. Reddy 1 1 Department of Veterinary Microbiology, College of Veterinary Science, Sri Venkateswara Veterinary University, Rajendranagar, Hydera- bad, India 2 Ella Foundation, Genome Valley, Turkapally, Shameerpet Mandal, Hyderabad, India 3 Department of Animal Biotechnology, Lala Lajpat Rai University of Veterinary & Animal Sciences, Hisar, Haryana, India Introduction Bluetongue (BT) is an emerging as well as transboun- dary disease caused by bluetongue virus (BTV). Although BTV can infect several species of wild and domestic animals, clinical manifestation is observed only in sheep, and to some extent in cattle (Hourrigan and Klingsporn, 1975; Erasmus and Christiaan, 2009; Elbers et al., 2009; Durand et al., 2010). Although the ability of the virus to survive and replicate in various host species, especially in wild animals, and subsequently be transmitted, is not well understood, spread rarely occurs without Culicoides midges (Erasmus and Christiaan, 2009). Hence, movement of animals and/or midges is the major reason for movement of the virus from one geographical location to another. This has led to many parts of the world, especially the tropics and the sub- tropics, being endemic for BTV. There are 24 confirmed serotypes of BTV, and two more have been recently proposed (Hofmann et al., 2008; Maan et al., 2009, 2011). Bluetongue virus is an Orbivirus containing segmented double-stranded RNA genome, the 10 segments encoding seven structural and three non- structural proteins (Pedley et al., 1988). VP2, an outer capsid protein, has the highest rate of sequence variation among all the proteins (Maan et al., 2004, 2007, 2009) and determines serotype. To some extent, VP5, another outer capsid protein, can also contribute to serotype determination (Ghiasi et al., 1987; Inumaru and Roy, 1987; Cowley and Gorman, 1989; Mertens et al., 1989; Keywords: bluetongue virus; genome sequence; phylogenetic analysis; virus movement; transboundary disease; modified live virus vaccine Correspondence: Dr P. P. Rao. Ella Foundation, Genome Valley, Turkapally, Shameerpet Mandal, Hyderabad 500078, India. Tel.: +91 40 2348 0571; Fax: +91 40 2348 0560; E-mail: raopp@ellafoundation.org Present address: G. Prasad, Assistant Director General (AH), 405, ICAR, Krishi Bhawan, New Delhi 110 114, India. Received for publication March 26, 2011 doi:10.1111/j.1865-1682.2011.01266.x Summary Bluetongue, a transboundary disease, is endemic in several tropical countries and is caused by bluetongue virus (BTV). The origin and movement of BTV can be predicted by comparing nucleotide sequences of its segmented RNA genome. Such analyses have been useful in evaluating the source of the virus responsible for recent incursion of BTV into previously unreported areas. Besides several serotypes, genetically related BTV strains circulate in each ende- mic area, but such clusters of strains have been reported to be distinct from one geographical region to another. We obtained partial or complete sequences of the open reading frames encoded by VP2, VP6, VP7, NS1 and NS2 genes of a BTV-10 isolate of India and compared them with other BTV-10 sequences available in public database. Sequences of all the five genes showed >99% iden- tity to BTV-10 prototype, vaccine strain and vaccine-like virus isolates from the USA. Our results suggest that Indian BTV-10 virus analysed in this study possibly originated from the United States. Transboundary and Emerging Diseases ª 2011 Blackwell Verlag GmbH • Transboundary and Emerging Diseases. 1