MECHANISMS OF HOSTSPECIFICITY OF CANINE DISTEMPER VIRUS

近年来，犬瘟热(CDV)在世界范围内的发病率呈上升趋势。我们从受感染的狗身上分离出了一些病毒。对血凝素(H)蛋白的遗传分析表明，最近分离的菌株具有更多的潜在糖基化位点。通过H基因的限制性片段长度多态性可以区分新型CDV和老型CDV，是日本流行该病的主要原因。通过与单抗的交叉反应分析，建议至少改变流行病毒H蛋白的一个中和表位。对柳中新分离株的全基因组进行了测序。该基因全长15690bp，推导的氨基酸序列与疫苗株的同源性约为92%。单粒病毒的反向遗传学是一种拯救传染性病毒的创新技术。我们在CDV上进行了该系统的开发，并成功地从CDV的结构基因之间具有唯一限制性内切酶位点的cDNA中回收了重组CDV，为进一步的基础和应用研究奠定了基础。另一方面，我们对日本沿海水生动物进行了麻疹病毒的流行病学调查。对300多种动物的血清学分析表明，日本沿海的鳍脚类动物似乎在1988年之前感染了类PDV病毒，而鲸目动物则在1978年感染了类DMV病毒。对日本一只浣熊新分离的CDV的遗传和血清学分析表明，H蛋白的氨基酸序列只有4个差异，表明在日本浣熊体内传播的病毒与最近在狗中暴发的CDV毒株属于同一群。

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.