Hepatitis B causes

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

The hepatitis B virus is an hepadnavirus with a DNA genome. The viral particle consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity. It shows tropism for hepatocytes and humans are its only natural reservoir.

Taxonomy

Viruses; Retro-transcribing viruses; Hepadnaviridae; Orthohepadnavirus

Biology

Hepatitis B virions Courtesy: World Health Organization

The genome organisation of HBV. The genes overlap. Courtesy: [Wikimedia Commons]

The hepatitis B virus, an hepadnavirus, is a 42 nm partially double stranded DNA virus, composed of a 27 nm nucleocapsid core (HBcAg), surrounded by an outer lipoprotein coat (also called envelope) containing the surface antigen (HBsAg).

Hepatocytes infected in vivo by hepadnaviruses produce an excess of noninfectious viral lipoprotein particles.

Tropism

Hepatitis B virus shows tropism for hepatocytes.

Natural Reservoir

The natural reservoir for hepatitis B virus is man. Closely related hepadnaviruses have been found in woodchucks and ducks, but they are not infectious for humans.