Hepadnaviruses

Hepadnaviruses are a family of viruses known for their distinctive replication cycle, which involves a unique reverse transcription step. This family includes viruses that infect mammals, birds, and reptiles. The most well-known member is the Hepatitis B virus (HBV), which primarily affects humans and causes hepatitis, a liver inflammation. Other hepadnaviruses include woodchuck hepatitis virus (WHV), ground squirrel hepatitis virus (GSHV), and Pekin duck hepatitis virus (DHV).

These viruses are characterized by their small, enveloped virions with an icosahedral capsid. Their genome is partially double-stranded DNA, which is characteristic of their replication strategy. Upon entering a host cell, the viral DNA is repaired and transcribed into an RNA intermediate called pregenomic RNA (pgRNA). This pgRNA then serves as the template for a viral reverse transcriptase enzyme to synthesize new viral DNA.

Hepadnaviruses are transmitted through blood and body fluids. Infection can range from acute, self-limiting illness to chronic infection, which can lead to serious liver diseases such as cirrhosis and hepatocellular carcinoma (liver cancer). Diagnosis typically involves blood tests to detect viral antigens or antibodies. Prevention strategies for HBV include vaccination and safe practices to avoid exposure to infected bodily fluids. Treatment options for chronic HBV infection exist and aim to suppress viral replication and manage liver disease.