1High Security Animal Disease Laboratory, IVRI, Anand Nagar, Bhopal-462021, India
2Indian Veterinary Research Institute, Hebbal, Bangalore-560024, India
3PD ADMAS, IVRI Campus, Hebbal, Bangalore-560024, India
4Division of Virology, IVRI, Mukteshwar-263138, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Bluetongue, caused by Bluetongue virus (BTV), is an important viral disease of sheep in India. The BTV is transmitted by the bite of Culicoides midges and almost 21 serotypes of the virus are circulating presently in different ruminant species in India. Segment 10 (S10) of BTV genome codes for non-structural protein NS3/3A, which is essential for virus assembly and release of BTV particles from infected cells. It has been proved that BTV S10 based phylogenetic studies are important in understanding the evolution of different BTV isolates and topotype analysis. Hence, nucleotide sequences (690 bases each) of NS3/3A coding region of S10 gene of six different BTV isolates (one BTV1, three BTV18 and two BTV23) from India were generated and the corresponding amino acid sequences were deuced. The MEGA 4 programme based phylogenetic analysis of S10 genes placed all Indian BTV isolates along with BT viruses from Mediterranean Basin, Australia and Asia in a different subclade where in Indian BTV18 and BTV23 serotypes formed a single monophyletic cluster distinct from another monophyletic group of BTV1 isolates from India. The deduced NS3/3A amino acid sequences confirmed that the potential glycosylation sites at amino acid (aa) residue 63 and 150, the cysteine at residue 137, a tryptophan residue at aa position 159 and the PPXY and PS/TAP late domain motifs between aa 36 and 44 were conserved. The significant aa substitutions that occurred only in Indian BTV isolates were Q to R at residue 35 (in BTV18RIND), A to V at residue 40 and H to Y at residue 97 (in BTV1AIND as in BTV1f1IND and BTV1f2IND), A to V at residue 48 and P to L at residue 220 (in BTV1AIND) and L to M at residue 177, C to S at residue 181 and P to Q at aa position 220 (in BTV18BIND). It was concluded that S10 gene sequences of all BTV isolates from India were largely conserved (>95.7% homology).
