HBsAg

Overview
HBsAg is the surface antigen of the Hepatitis-B-Virus (HBV). The capsid of a virus has different surface proteins from the rest of the virus. The antigen is a protein that binds specifically on one of these surface proteins. Today these antigen-proteins can be a genetically manufactured (e.g. transgene E.coli) to produce material for a simple antigen test, which finds out the presence of HBV.

It is commonly referred to as the Australian Antigen.

It is present in the sera of patients with viral hepatitis as well as in normal populations in the tropics and the southeast Asia. However, it is rarely present in patients with infectious hepatitis.

It was first isolated by the American research physician and Nobel Prize winner Baruch S. Blumberg (1925) in the serum of an Australian aborigine.