Hepatitis B virus

species of the genus Orthohepadnavirus

thumb|The genome organisation of HBV; the genes overlap. ORF S, in green, encodes HBsAg. thumb|HBsAg under a transmission electron microscope: the protein self assembles into [[virus-like particles]] HBsAg (also known as the Australia antigen) is the surface antigen of the hepatitis B virus (HBV). Its presence in blood indicates existing hepatitis B infection.

Hepatitis B virus X-interacting protein is a protein that in humans is encoded by the HBXIP gene.

thumb|Schematic overview of the hepatitis B virus particle. HBcAg is a constituent of the nucleocapsid core (green hexagon). thumb|The genome organisation of HBV. Some genes overlap. (ORF Core, at bottom left, encodes HBcAg.

species of virus

cccDNA (covalently closed circular DNA) is a special DNA structure that arises during the propagation of some viruses in the cell nucleus and may remain permanently there. It is a double-stranded DNA that originates in a linear form that is ligated by means of DNA ligase to a covalently closed ring. In most cases, transcription of viral DNA can occur from the circular form only. The cccDNA of viruses is also known as episomal DNA or occasionally as a minichromosome.