Advances in Animal and Veterinary Sciences
Diversity among Topotypes of Bluetongue Virus Serotype 9 as Revealed by Whole Genome Sequence Analysis
Sushila Maan1*, Arnab Ghosh1, Kanisth Batra1, Aman Kumar1, Narender Singh Maan2
1Department of Animal Biotechnology, College of Veterinary Sciences, LLR University of Veterinary and Animal Sciences, Hisar, 125 004, Haryana, India; 2Department of Animal Nutrition, College of Veterinary Sciences, LLR University of Veterinary and Animal Sciences, Hisar, 125 004, Haryana, India.
*Corresponding author: sushilamaan105@gmail.com
ABSTRACT
To understand the diversity and molecular epidemiology of bluetongue virus serotype 9 (BTV–9), the complete genomes (19,177 base pairs) of several strains of BTV–9 originated from Europe, Greek islands, Mediterranean basin, Middle East, South Africa, Australia and Indian subcontinent were compared. These comparisons showed that all ten genome segments of a south African reference strain (RSArrrr/09) and its derivative vaccine strain (RSAvvvv/09) belong to western lineage, showing only 68% – 69% nucleotide (nt) identity with the eastern topotypic field strains including eastern strain from Australia (DP0837), Europe and Mediterranean region as well as reassortant strains from India. These detailed comparisons involving global strains showed that there is a very high degree of variation (up to 32%) between BTV–9 strains from eastern and western geographical regions. Full genome sequencing and availability of data are therefore highly recommended in order to quickly and accurately identify the emergence of viruses with novel genome segment constellation. These studies can also help to identify representative suitable ‘reference–strain’ of eastern topotype (BTV–9e), western topotype (BTV–9w), as well as ‘cross–topotype’ reassortant strains (BTV–9r) of BTV–9 which are circulating in the field.
Key Words: Orbivirus, Bluetongue virus, BTV–9, Reference strain, Topotype, Whole genome sequencing
