Molecular characterization of canine distemper virus from Tamil Nadu, India

Abstract

The focus of the present study was to detect canine distemper virus in clinically suspected dogs and its molecular characterization. The detection of CDV N gene was carried out using RT-PCR and Nested PCR. The N gene positive cDNA were used for the amplification of partial H and F genes. H gene positive products were subjected to restriction digestion with NdeI. Phylogenetic tree of partial CDV H and F gene nucleotide sequences were constructed using maximum likelihood method.Attempts were made to isolate CDV in vero cells expressing SLAM and MDCK cell lines. Out of the 90 samples collected from CDV suspected dogs, 19 samples (21%) were found positive by RT-PCR and 21 samples (23%) by nested PCR. When the N gene positive cDNA were subjected to PCR amplification of partial H and F gene sequences, 1 positive amplification each was obtained for H and F genes using the published primers and 2 H and F gene positive amplifications were obtained using the primer designed in this study. Restriction digestion of the partial H gene products yielded 2 fragments, proving the CD viruses to be wild-type. Phylogenetic analysis of partial H and F gene nucleotide sequences revealed that the field CD viruses of this study were distinct and varied from the vaccine strain. None of the samples produced cytopathic effects evenafter 3 passages in 2 different cell lines. However, the presence of virus in 1 sample in both the cell lines after second passage was confirmed by RT-PCR.