Cooperative studies of seroepidemiology and pathogenesis of Viral and parasitie diseases in Okinawa and Thailand

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The cooperative study consists of three fields : 1. Flavivirus infections, specifically Japanese encephalitis(JE) and dengue hemorrhagic fever(DHF). 2. Herpes simplex virus type 2(HSV 2) infection. 3. Strongyloidiasis.Results obtained are described briefly as follows :1. Cross immune response between JE and DHF was examined by neutralization(N) tests. When individuals with pre-existing N antibody to JE or dengue virus were infected sequentially with dengue or JE virus, significant increases of N titer were observed not only to the causative virus but also to the previously infected virus at the frequency of 35%-40%. Thus, even the N test could not always identify the causative virus in re-infection of flaviviruses.The truncated dengue-4 E protein produced by a recombinant baculovirus was wxamined for the possibility of diagnostic antigen to differentiate dengue and JE infection. Results indicated that the expressed protein was a useful diagnostic antigen in differentiation of dengue in … More fection from JE with slightly lower specificity than N test.RT-PCR method was examined for the early diagnosis of DHF. Appropriate selections of primers for RT-PCR resulted in a useful identification method of 4 serotypes of dengue virus in comparison with virus isolation.2. HSV 2 isolates in Okinawa and Chiang Mai were analyzed by the restriction endonuclease cleavage patterns and virulence to mice. Some cleavage patterns characteristic to each regional isolate were observed. The Okinawan isolates showed higher, intermediate and lower virulence while the Chiand Mai isolates showed only intermediate virulence to mice by peripheral injection3. Field study on strongyloidiasis in Chiang Mai gave positive rates of 46.3% in adult villagers and 6.9% in school children.The newly developed ELISA for strongyloidiasis gave well-corresponding results with those of the stool culture examination for the Okinawan samples but did not for the Chiang Mai samples, possibly due to cross reactions caused by co-infections with other intestinal parasites such as Opisthorchis viverrini and hookworm, which were found to be highly prevalent in the Chiang Mai area. Less