Hepatitis B Virus.

This infographic about hepatitis B virus explores its replication cycle, natural history of infection and pathogenesis, and how this can be controlled and treated. Hepatitis B virus (HBV) is a common worldwide blood-borne pathogen. Chronic hepatitis B can progress to an inactive carrier state, and then, in some patients, give rise to cirrhosis and cancer of the liver, leading to death. An HBV surface-antigen vaccine is effective, but treatments are currently not curative. HBV replicates via reverse transcription. Its covalently closed circular (ccc) DNA in the nucleus encodes a pregenomic RNA (pgRNA), which can be encapsidated by HBV polymerase. Reverse transcription occurs in the capsids by using the pgRNA as a template for the synthesis of single-stranded linear and then partially double-stranded relaxed circular (rc) DNA. Capsids containing a mature rc DNA genome target to the nucleus for ccc DNA synthesis. Persistent HBV infection is caused mainly by ccc DNA and immune tolerance to HBV antigens in the liver. Unlike acute infection, chronic carriers contain only a low level of HBV core-antigen-specific T cell activity, contributing to the lack of viral clearance.