Molecular epidemiological studies on Japanese encephalitis and dengue viruses in Asia

本研究旨在通过分子流行病学研究来阐明流行性乙型脑炎病毒的越冬问题，即病毒是在温带气候中持续存在还是在夏季从热带地区传入，这与在流行间期发现病毒的方法有很大不同。本研究还旨在获得病毒毒力因子在登革出血热发病机制中的可能作用的信息。登革出血热自1953年首次暴发以来一直是东南亚国家的主要病毒性疾病。研究中使用了3型和4型登革热病毒。将这些病毒在白纹伊蚊克隆C6/36细胞中大量培养，并通过聚乙二醇沉淀和超离心从感染的液体中浓缩和纯化病毒。病毒RNA为ph ...更多信息 从沉淀的病毒中提取烯醇，并通过蔗糖梯度沉降纯化，以获得42 S病毒体RNA。用T1-RNase消化RNA，用多核苷酸激酶和<r^（32）> P-ATP标记。用双向凝胶电泳和放射自显影技术对标记核苷酸进行分析，发现日本分离的乙脑病毒与1980年以后东南亚分离的乙脑病毒指纹图谱有很大的不同。这一发现支持病毒在冬季持续存在于日本某处的假设。在菲律宾分离的3型登革热病毒的指纹模式与印度尼西亚分离的病毒的指纹模式截然不同。这些分离物的指纹图谱也与泰国分离物的指纹图谱不同。即使分离年份相差10年，菲律宾分离物的指纹图谱也相当相似，印度分离物也是如此。从印度尼西亚同一流行季节的重症出血热病例中分离的3型病毒与从轻型病例中分离的3型病毒之间存在11个斑点差异。少

The study was performed to clarify the unsolved problem of overwintering of Japanese encephalitis; whether the virus persists in the temperate climate or it is introduced from tropical area during the summer time, by using molecular epidemiological studies, which is quite different from those to find out the virus during interepidemic season. The study also aimed to obtain informations on the possible role of virus virulence factor in the pathogenesis of dengue haemorrhagic fever, which has been a major viral disease in Southeast Asian Countries since the first outbreak in 1953.The strains of Japanese encephalitis virus isolated from 1935 to 1983 in Japan as well as in foreign countires was used for the analysis. Dengue virus type 3 and 4 were used in the studies. These viruses were grown in Aedes albopictus clone C6/36 cells in mass culture and the virus was concentrated and purified from the infected fluid by polyethylene glycol precipitation and ultracentrifugation. Viral RNA was ph … More enol-extracted from the pelleted virus, and purified by the sucrose gradient sedimentation to obtain 42S virion RNA. The RNA was digested by T1-RNase and labeled by polynucleotide kinase and <r^(32)> P-ATP. The labeled nucleotides were analyzed by 2-dimensional gel electrophoresis and revealed by the autoradiography.The fingerprints of Japanese encephalitis virus isolated in Japan were quite different from those of southeast Asian isolates after 1980. The finding was in favour of the hypothesis that the virus persists somewhere in Japan during winter season.The fingerprint pattern of type 3 dengue virus isolated in the Philippines was quite distinct from those of the Indonesian isolates. The fingerprints of these isolates were also different from those of Thailand. The fingerprints of the Philippine isolates were rather similar even when the year of isolation showed 10 years difference, so were the Indoensian isolates. There were 11 spots difference between the type 3 dengue virus isolated from severe haemorrhagic fever case from the strain isolated from mild case in the same epidemic season in the Indonesia. Less