Treatment Options for Hepatitis B

Hepatitis B virus (HBV) is an enveloped DNA virus with a double-stranded circular genome that replicates through an RNA intermediate within the host hepatocyte (1,2). The virus infects the hepatocyte and is converted to covalently closed circular DNA, which serves as a template for viral replication. When the replication cycle of HBV is complete, mature, infectious virions are released into the bloodstream (1–3). The virus itself is noncytopathic, and the mechanism of cellular injury is immune-mediated. Viral clearance is mediated by both cytopathic and noncytopathic pathways and, although the majority of individuals are able to clear the virus and exhibit firm immunological control, some individuals fail to mount an adequate immune response to eliminate the virus, which leads to chronic infection (3,4). Chronic infection appears to be associated with inadequate or exhausted T cell responses to the virus, such that most patients with chronic HBV infection have few or no HBV-specific T cells in their circulation (2). The use of nucleoside analogue treatments may transiently restore T cell responses (5,6).