Hepatitis B and the Immune System

As a persistent virus, hepatitis B virus (HBV) is believed to be noncytopathic in most circumstances, with its disease pathogenesis mediated by host innate and adaptive immune responses. Although HBV may initially avoid activating critical innate intracellular defenses (eg, type I interferons), T cells exert both cytopathic and noncytopathic antiviral effects toward resolution of HBV infection. With chronic HBV infection, various immune regulatory or tolerance mechanisms are induced with varying degrees of effector T-cell dysfunction and liver inflammation, which contributes to liver disease progression. This review highlights some components of host immune response relevant for HBV infection, including the more recent appreciation of immune regulatory mechanisms induced during chronic viral infection. Although therapeutic options are evolving for HBV, a better understanding of its immune pathogenetic and regulatory mechanisms may help develop better approaches to treat HBV infection and prevent disease progression.