Persistent infection of hepatitis C virus (HCV) is a major cause of liver diseases such as chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Searching for a substance with anti-HCV potential, we examined the effects of a variety of compounds on HCV replication using a HCV subgenomic replicon cell culture system. Consequently, the immunosuppressant cyclosporin A (CsA) was found to have a suppressive effect on the HCV replicon RNA level and HCV protein expression in these cells. CsA also inhibited multiplication of the HCV genome in a cultured human hepatocyte cell line infected with HCV using HCV-positive plasma. This anti-HCV activity of CsA appeared to be independent of its immunosuppressive function. In conclusion, our results suggest that CsA may represent a new approach for the development of anti-HCV therapy. (HEPATOLOGY 2003;38:1282-1288 P ersistent infection with the hepatitis C virus (HCV), identified as the major causative agent of non-A, non-B hepatitis, 1,2 has been closely related to liver diseases such as chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. 3 The development of these liver diseases from HCV carriers, an estimated 170 million people throughout the world, is a major public health problem. Effective anti-HCV therapy has been restricted mainly to therapy with interferon (IFN) and a combination of IFN and ribavirin. However, because the virus is not eliminated from approximately one half of HCVinfected patients treated with these agents, 4 alternative approaches to the treatment of HCV infection are needed.Recently, an HCV subgenomic replicon cell culture system has been established in which an HCV subgenomic replicon autonomously replicated in Huh-7 cells (HCV replicon cells). 5 This replicon is composed of the HCV 5Ј-untranslated region containing an internal ribosomal entry site, the neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural proteins (NS) 3 through NS5B; and the HCV 3Ј-untranslated region (Fig. 1A). This system provides a unique tool for studying the mechanisms of HCV replication and screening as well as evaluating anti-HCV compounds. Taking advantage of this feature, we examined the effects of various types of compounds on the replication of HCV using HCV replicon cells established in our laboratory 6 (Miyanari et al., manuscript accepted for publication). Consequently, we found that a well-known immunosuppressant, cyclosporin A (CsA), 7 had a strong suppressive effect on HCV replication in these cells. Moreover, we found suppressive activity of CsA for multiplication of the HCV genome in cultured human hepatocytes infected with HCV. The mechanism of the anti-HCV activity of CsA was also studied.
Materials and MethodsCell Culture. Huh-7 and MH-14 cells, HCV replicon cells, were cultured in Dulbecco's modified Eagle medium with 10% fetal bovine serum. PH5CH8 cells were cultured in a 1:1 mixture of Dulbecco's modified Eagle medium and F12 medium supplemented with 100 ng/mL epidermal gro...