| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1995: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Research Abstract |
Clinical significance of the subtypes of hepatitis C virus (HCV) was studied. Seven (1a, 1b, 2a, 2b, 3a, 3b, 4a) subtypes of HCV were determined by blotting using type specific cDNA probes at the NS5 region. In about 1,600 samples obtained from the world, HCV-3b was not found, and HCV-4a was detected occasionally mainly in samples from Africa. indicating these two types distributed in only limited area, and the other 5 types commonly distributed through the world. To obtain the accurate results of HCV subtypes, a combined analysis with different methods for typing was needed. In a nationwide analysis in Japan, it was confirmed that the effects of interferon (IFN) treatment were significantly better in HCV 1b-related patients than in non-related patients. In the Western countries, the effect of IFN treatment tended to be better in patients with HCV-3a than HCV-1b. The pattern of changes in HCV titers during IFN treatment was classified into 3 types : rapid decreased (A) type, high titer
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sustained (C) type and intermediate (B) type between A and C types. The pattern of C type was found only in patients with HCV-1b and not with HCV-2a and-2b, suggesting that the difference of IFN effects between HCV subtypes may be attributed to the difference of quality of HCV subtypes and not to the quantities of HCV-RNA.Quansispesies population of HCV at the IFN sensitivity determining region were analyzed using single strand conformation polymorphism. In C type, the most quasispesies were IFN-resistance type. On the other hand, the most quasispesies in A type were IFN sensitive type. The prevalence of HCV-1b in different countries of the world was significantly correlated with the incidence of hepatocellular carcinoma (HCC). In Japan, a significant correlation between the prevalence of HCV-1b and mortality rate by HCC in different prefectures was found. The prevalence of HCV-1b in patients HCC was significantly higher than patients without HCC.The duration for the development of HCC was shorted in HCV-1b than the other subtypes of HCV., These results suggest that the oncogenecity of HCV-1b may be stronger than the other subtypes of HCV. Less
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