Persistence of HCV in quiescent hepatic cells under conditions of an interferon-induced antiviral response

Hepatitis C virus (HCV) is a common cause of chronic liver disease. Many patients do not clear the viral infection; little is known about the mechanisms of HCV persistence or the frequent failure of interferon (IFN) to eliminate it. Better culture systems are needed to study viral replication in quiescent liver cells.

Methods: We used human hepatoma (Huh7.5) cells and those that had undergone proliferation arrest and differentiation (Huh7.5dif) to study the persistence of HCV infection following exposure of the cells to IFN-α and to compare the antiviral effects of IFN-α and IFN-λ. We validated these results with primary human hepatocytes and Huh7 cells that expressed an IFN-inducible fluorophore.

Results: Following infection of Huh7.5dif cells, HCV replicated persistently and released infectious particles. Long-term exposure of the cells to IFN-α reduced HCV replication 1000-fold but did not eliminate the virus; viral replication rebounded after withdrawal of IFN, as it does in patients with chronic HCV infection. HCV replicated at higher levels, but not exclusively, in cells that had a low level of response to IFN-α. Following incubation of cells with equipotent concentrations of IFN-α or IFN-λ, Huh7.5dif cells expressed a wider pattern of IFN-stimulated genes than undifferentiated Huh7.5 cells or primary human hepatocytes, indicating that the antiviral response depends on the differentiation status of the cells.

Conclusions: We developed a cell culture system using hepatoma cells to study persistent HCV infection during the type I or type III IFN-induced antiviral response. The level and range of the antiviral responses were associated with the differentiation status of the cells. We propose that HCV exploits the stochastic nature of the response of hepatocytes to IFN to sustain persistence.