Rethinking cytokine function during hepatitis A and hepatitis C infections

Hepatitis A virus (HAV) and hepatitis C virus (HCV) are both viruses with hepatotropic lifestyles. HAV induces an acute infection that results in the elimination of the virus by the host whereas HCV is typically able to establish a persistent infection that may result in cirrhosis and hepatocellular carcinoma. The mechanisms responsible for this difference are unknown. However, given HAV and HCV are both non-cytophatic viruses, the observed symptoms and liver injury during the infections are the result of specific immune responses under the control of cytokines. Thus, the production of cytokines during hepato- tropic viral infections may constitute a mechanism leading to different outcomes. Therefore, understand- ing the differences in the cytokine patterns induced in response to HAV and HCV is likely to provide important insights into the cytokine-mediated mechanisms underlying the long-term persistence of HCV, the broad spectrum of clinical manifestations induced by HAV and the resolution of HAV infection during the acute phase. Herein, we focus on discoveries that hold promise in identifying cytokines as therapeutic targets for the treatment of viral hepatitis.