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Advances in Animal and Veterinary Sciences

Research Article
Adv. Anim. Vet. Sci.1 (4S): 14 - 19. Special Issue-4 (Progress in Research on Viruses and Viral Diseases)
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Pawan Kumar1, Prasad Minakshi1*,Koushlesh Ranjan1, Ravinder Dalal1, Gaya Prasad1, 2
1Department of Animal Biotechnology, College of Veterinary Sciences, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar 125004, Haryana, India; 2Indian Council of Agricultural Research, Krishi Bhawan, New Delhi 110001, India
*Corresponding author: minakshi.abt@gmail.com

ABSTRACT
The dsRNA genome of bluetongue virus (BTV) consists of 10 segments that encodes for seven structural and four non–structural proteins. The nucleotide variations of core, NS1 and NS2 proteins, in addition to capsid proteins helps determine the geographical origin (eastern or western geographical group/ topotype) of virus isolates. International trade of vaccinated livestock are playing major role in intercontinental movement of western BTV strains or genome segments in India. The co–circulation of different virus isolates, being the segmented nature of genome, provides an opportunity to simultaneously infect the same animal or even same cell with the potential of generating reassortant viruses. The data regarding the prevalence of viral topotype/ nucleotype/ serotype is essential to establish phylogenetic relationship and intercontinental migration of the pathogen which in turn help in formulation of proper intervention strategies against the disease. We carried out full length sequencing of genome seg–5 (ns1 gene) of Indian isolate VJW64 (BTV16). Sequence identity and phylogenetic analysis revealed that genome seg–5 clusters with isolates of western topotypes showing nucleotide similarity of more than 89.5% compared to the less than 78% sequence identity with isolates of eastern geographical group that formed a separate monophyletic clade. However our previous study indicated that seg–2 and seg–6 of Indian isolate VJW64 (BTV16) belong to eastern topotypes of bluetongue virus. Thus VJW64 isolate is a reassortant virus containing segments derived from both eastern and western topotypes. The study provides an evidence of circulation of a reassortant of BTV16 serotype in India for the first time.

Key Words: Bluetongue virus, Genome seg–5, Reassortment, Topotypes