Cloning and hereditary variety analysis of H gene of canine distemper virus detected in naturally infected raccoon dogs, foxes and minks.

To characterize the variability of recent field isolates of 5 canine distemper virus(CDV) strains from different hosts and geographical areas,we conducted nucleotide sequence analysis of the H gene encoding the haemagglutinin protein.Pronounced differences between 5 field isolates were revealed in comparison to the attenuated vaccine strains vacChina,Convac and Onderstepoort.Phylogenetic tree was constructed with H gene of 5 CDV isolates,vaccine strain vacChina and 12 CDV strains in GeneBank.Results: The homology of nucleic acid sequences among the 5 isolates was high(97.6%—99.9%).The homology of nucleic acid sequences between vacChina and 5 isolates was low(90.5%—91.8%)while high with foreign vaccines,vacConvac(H:96.8%) and vacOnderstepoort(H:97.2%).The difference of amino acid homology of H protein among 5 isolates was not high(97.1%—100.0%).The homology of H protein between vacChina and 5-isolates was low,with H protein 89.7%—91.8%.VacChina and Onderstepoort,Convac had high homology of amino acid in H protein.Conclusion: The CD prevalence in several provinces of China this summer may be due to the far heredity between vaccine strain and field strains.