MECHANISMS OF HOSTSPECIFICITY OF CANINE DISTEMPER VIRUS

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Recently, the incidence of canine distemper (CDV) in domestic dogs has increased in the world. We isolated numbers of viruses from affected dogs. Genetic analysis of the Haemagglutinin (H) proteins revealed that the recent isolated strains have an increased number of potential sites for glycosylation. We also revealed that the prevalence of the disease in Japan mainly caused by new types of CDV which could be distinguished from vaccines and old types of CDV by restriction fragment length polymorphism of H genes. By the analyses of cross-reactivity to monoclonal antibodies, at least one neutralizing epitope of the H protein of prevalent viruses was suggested to be changed. The full genome of the Yanaka strain, a new isolate was sequenced. It contains 15,690bp of nucleotides and deduced amino acid sequence had approximately 92% of homology compared with that of vaccine strain. The reverse genetics of Mononegavirales is an innovative technique for the rescue of infectious viruses. We conducted to develop this system on CDV and succeeded to recover recombinant CDV from the cDNA of CDV with unique restriction enzyme sites between structural genes for further basic and applied studies. On the other hand, we conducted the epidemiological survey of morbilliviruses on aquatic animals in the coast of Japan. Serological analysis of more than 300 animals including cetaceans and pinnipeds indicated that the pinnipeds appeared to have been infected with PDV-like virus before 1988 and cetaceans with DMV-like 1978 along the coast of Japan. The genetic and serological analyses of a newly isolated CDV from a raccoon dog in Japan revealed that only four differences in amino acids sequence of H protein indicating that the virus spreading in Japanese raccoon dogs belongs to the same group as the CDV strains causing recent outbreaks in dogs.