Department of Infectious Diseases and Center for Liver Diseases, Peking University First Hospital, Beijing, China.
Chronic hepatitis B (CHB) is characterized by an impaired immune response to hepatitis B virus. Among the nucleos(t)ides used in CHB treatment, telbivudine is associated with the highest rates of hepatitis B e antigen (HBeAg) seroconversion rates, which are similar to those observed with pegylated interferon (PegIFN). Besides direct antiviral effect, modulation of the immune system may be an additional benefit for telbivudine-treated patients. Indeed, there is much clinical data indicating an IFN-like behaviour for telbivudine in contrast to other oral nucleos(t)ides, such as high HBeAg seroconversion, similar hepatitis B surface antigen (HBsAg) decline and biphasic viral kinetics. Clinical studies, animal models and in vitro studies suggest that both the innate and adaptive immune system responses contribute to high HBeAg seroconversion during telbivudine treatment through modulation of the function and/or expression of CD4+/CD8+ T cells, Th1/Th2, Treg, PD-1/PD-L1, Th17, IL-21 and TFH. The results described in this review suggest that the antiviral effect of telbivudine may be attributable not only to direct suppression of hepatitis B virus, but also to immunoregulatory effects. Hypothetically, telbivudine shares some common signal pathways with IFN.