| Summary: | 碩士 === 國立中山大學 === 生物科學系研究所 === 93 === Tzukuan is an HBV-, HCV-, HDV- endemic township in southern Taiwan. Based on a mass screening on 2909 residents age of 45 years or more in 1997, the prevalence rates of HBsAg and anti-HCV were 12.8% and 41.6% respectively. Of HBsAg carriers, 15.3% were positive for anti-HDV. Tzukaun was divided into coastal area and inland area. The prevalence of anti-HCV of coastal area was two times higher than that of inland area (61.4% v.s. 29.1%) and genotype 1b and 2a are the main two subtypes. We wish to find the causes of discrepancy in these nearby areas by phylogenetic analysis. Stratified by the living areas, coastal or inland, 27 samples were picked up (ingroup). HCV sequence of NS5B region could be detected by RT-PCR then a nested PCR in eight males and ninteen females with mean age of 54.8 years old (range: 45-70). None of these 27 residents came from the same family. Another 10 HCV infected persons whose living townships also in southern Taiwan but other than Tzukuan were enrolled as local controls. From GenBank, 30 different HCV isolates were included. Phylogenic analysis unequivocally confirmed the simultaneous spread of two different HCV strains in this township clusters according to their subtypes were noted. A trend of the spreading from coastal to land area or an ultra-aggregation phynomenon which according to their living area, as we suspected, were not noted between Tzukuan’s residents. In ingroup, the short genetic distance between the isolates of C hepatitis virus which came from different villages might be caused from the wide-spreading of HCV in this endemic area (the maximal and minimal genetic distance in 1b or 2a isolates are 0.0869 vs. 0.0098 and 0.0996 vs. 0.0334). Besides, according to the contacting history to foreigner by our aborigine tribes, from genebank, all isolates from different countries were included and three possible origins of HCV genotype 1b were noted in Tzukuan. All these findings might be caused from frequently HCV inflow in this endemic area and wide-spreading of HCV between different countries.
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