Walsh & Hoyt: Hepadnaviridae (Hepatitus B Virus)

The DNA viruses that make up the family Hepadnaviridae have unique ultrastructural, molecular, antigenic, and biologic features that distinguish them from members of all previously recognized virus families. These hepadnaviruses are small and contain DNA that is circular. Because part of this DNA is single-stranded and part is doublestranded, the method of replication of these viruses is unlike that of any other DNA viruses. They also have a striking tropism for hepatocytes (hence the family name) and a propensity to cause persistent infection, with high concentrations of viral antigen consisting of complete and incomplete viral forms remaining in the blood continuously for months to years. One virus in this family is an important cause of human infection that has some neuro-ophthalmologic significance. This virus is called the hepatitis B virus (HBV) to distinguish it from two RNA viruses, the hepatitis A virus, which produces a somewhat similar clinical picture, and the hepatitis C virus, a flavivirus that produces completely different clinical manifestations.