H gene-based molecular characterization of field isolates of canine distemper virus from cases of canine gastroenteritis

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.

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.

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.