[Genetic Variations and Cellular Receptors of Canine Distemper Virus--a Review]

Canine distemper (CD) caused by Canine distemper virus (CDV) was first reported in 1905, and has been one of the most serious contagious diseases of dogs as well as other carnivores. Recently, increasing cases of canine distemper (CD) both in vaccinated and unvaccinated dogs and in wildlife have been reported in Japan, America, Europe and Africa. Based on phylogenetic analysis of the hemagglutinin (H) gene sequences, six genotypes of CDV were distinguished. Antigenic heterogeneity of the H protein that provides an important protective antigen against CDV infection has been observed between wild-type CDV and vaccine strains. So it was suspected that the vaccines currently used can no longer efficiently protect animal from present-day circulating CDV infection. The host range of CDV includes all species of the families Canidae and many other species. Both signaling lymphocyte activation molecule (SLAM) and heparin sulfate (HS) expressed on the cells of the immune system or other non-lymphoid tissues can act as the cellular receptors for CDV, and are one of the major determinants of the host range and tissue tropism. In this review, we discussed the above-mentioned issues based on the recent research progress and the studies in our laboratory.