Objective  To perform etiological investigation of canine distemper virus (CDV) infection in dogs from Guangzhou and Dongguan, moniter the genetic evolution of canine CDV, and provide a data basis for the prevention and control of canine distemper (CD).

Method  Seventeen CDV positive samples were identified from dogs with CD symptoms. The haemagglutinin ( H ) genes of these wild strains were obtained by RT-PCR, and the H gene sequences were compared and analyzed through bioinformatics approach.

Result  The similarities of nucleotide and amino acid sequences of H genes from 17 CDV strains were 97.4% to 100.0% and 97.5% to 100.0%, respectively. Compared with vaccine strains such as Onderstepoort, Lederle and Convac, the similarities of nucleotide and amino acid sequences of H genes from these CDV strains were 90.3% to 91.5% and 89.4% to 90.8%, respectively. Phylogenetic tree analysis showed that 17 CDV wild strains belonged to Asia I subtype and were distant from the vaccine strains. The identified wild strains had evolved to containing nine potential N-glycosylation sites.

Conclusion  Asia I CDV is still an epidemic subtype in this region and this subtype is stable, but it has formed a certain evolutionary distance and a large number of mutations compared with vaccine strains. Therefore, it is of great significance to continue to monitor the evolution of CDV in dog populations.