Study on infection and maturation mechanisms of hepatitis C virus and its host response.

为了探讨丙型肝炎病毒(HCV)感染的分子机制，我们在293T和CHO细胞中制备了以水疱性口炎病毒(HCVpv)为基础的含有未经修饰的丙型肝炎病毒包膜蛋白的伪型病毒。293T细胞(HCVpv/293T)产生的HCVpv对HuH7细胞具有较强的感染性，但对HepG2细胞不具感染性。抗hCD81抗体可中和HCVpv/293T对Huh7细胞的感染，这与293T细胞产生的以小鼠白血病病毒(HCVpp)为基础的伪型病毒一样。而在CHO细胞中产生的HCVpv(HCVpv/CHO)对hCD81阴性的HepG2细胞具有较强的感染性，对HuH7细胞的感染性较弱。这些结果表明，HCVpv/293T和HCVpv/CHO分别具有hCD81依赖和非独立感染性。慢性丙型肝炎患者血清有效地中和了HCVpv/293T感染，而对HCVpv/CHO感染仅有轻微的抑制作用。在感染窗口期从丙型肝炎患者的血清中自然产生的丙型肝炎病毒颗粒也显示与Huh7和HepG2细胞结合。总之，这些结果表明，丙型肝炎病毒的细胞嗜性是由产生的细胞系决定的，至少有两种类型的丙型肝炎病毒颗粒与表现出hCD81依赖和独立感染的假型病毒具有相似的性质，在丙型肝炎患者血清中循环。

To examine the molecular mechanisms of hepatitis C virus (HCV) infection, we prepared pseudotype viruses bearing unmodified HCV envelope proteins based on vesicular stomatitis virus (HCVpv) in both 293T and CHO cells. HCVpv generated in 293T cells (HCVpv/293T) exhibited a high infectivity to Huh7 cells but not to HepG2 cells. The infection of HCVpv/293T to Huh7 cells was neutralized by anti-hCD81 antibody, as reported for the pseudotype viruses based on murine leukemia virus (HCVpp) generated in 293T cells. In contrast, HCVpv generated in CHO cells (HCVpv/CHO) exhibited a high infectivity to hCD81-negative HepG2 cells and a weak infectivity to Huh7 cells. These results indicate that HCVpv/293T and HCVpv/CHO exhibit hCD81-dependent and -independent infectivity, respectively. Sera taken from chronic hepatitis C patients efficiently neutralized HCVpv/293T infection, as reported for HCVpp infection, whereas only a slight inhibition of HCVpv/CHO infection was observed. Naturally occurring HCV particles in serum taken from a hepatitis C patient during the window period of infection also exhibited binding to both Huh7 and HepG2 cells. In conclusion, these results indicate that the cell tropism of the HCV pseudotype viruses is determined by the producing cell lines, and that at least two types of HCV particles bearing similar properties to the pseudotype viruses exhibiting hCD81-dependent and -independent infection circulate in the serum of hepatitis C patients.