Isolation and Phylogenetic Analysis of the Canine Distemper Virus from a Naturally Infected Dog in China

Abstract

Background: Canine distemper virus (CDV) can infect a variety of predators, such as Canidae, Mustelidae and Procyonidae family and cause high morbidity and mortality. Genetic/antigenic heterogeneity has been observed among various CDV strains, notably in the haemagglutinin (H) gene. Based on sequence analysis of the H gene, wild-type CDV strains can be divided into distinct genotypes. Methods: We used Vero/SLAM cells to isolate CDV strains from clinically naturally infected dog tissues. Here, the H gene sequence of the isolated strain was analyzed for the restriction enzyme polymorphism with RT-PCR-RFLP method and the method could be used to distinguish CDV vaccine strains from wild-type strains. Furthermore, the genetic and antigenic variation of the H gene was also analyzed.Result: Our results indicated that Vero cells expressing canine SLAM allow the efficient isolation of CDV wild-type strains. The isolated CDV was named Shandong strain. Phylogenetic analysis identified that Shandong strain was CDV wild-type strain, the Asian genotype I. Analysis of the potential glycosylation site of the H gene and determination of the neutralization titer PD50 showed that there were immunogenic differences between the Shandong strain and the vaccine strains.