H Gene-based Molecular Characterization of Field Isolates of Canine Distemper Virus from Cases of Canine Gastroenteritis

Background: Canine distemper virus (CDV) is one of the important causes for canine gastroenteritis. Its genome codes for six structural proteins N, P, M, F, H and L, of which H is important for viral pathogenesis. Availability of CDV molecular epidemiological data is sparse. Our study reports for the first time, isolation of enteric CDV from India and its molecular epidemiology. Methods: We isolated the circulating wild type CDV from cases of canine gastroenteritis recorded during 2019 in India. Partial H gene of the isolates was amplified and phylogeny was reconstructed with other isolates from the NCBI database using MUSCLE from MEGA7. Results: The multiple sequence alignment of the partial H gene of circulating CDV with reference isolates revealed 88-95% nucleotide identity, and 83-91% amino acid identity along with the presence of Nde1 restriction site at position 1571-1576 that is typical of wild type CDV isolates. Interestingly, phylogenetic analysis revealed that the circulating CDV were grouped with three different lineages i.e., South America-2, Asia-4, and Asia-5/India-1 and distantly related with the vaccine strains. Our study strengthens the need for the development of a relevant vaccine comprising of circulating viral strains for effective vaccination strategies.