Hepatitis B surface antigen
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
HBsAg is the surface antigen of the hepatitis B virus (HBV). It indicates current hepatitis B infection.
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.
Structure and function
The viral envelope of an enveloped virus has different surface proteins from the rest of the virus which act as antigens. These antigens are recognized by antibody proteins that bind specifically to one of these surface proteins.
Immunoassay
Today, these antigen-proteins can be genetically manufactured (e.g. transgene E. coli) to produce material for a simple antigen test, which detects the presence of HBV.
It is present in the sera of patients with viral hepatitis B (with or without clinical symptoms). Patients who developed antibodies against HBsAg (anti-HBsAg seroconversion) are usually considered non-infectious. HBsAg detection by immunoassay is used in blood screening, to establish a diagnosis of hepatitis B infection in the clinical setting (in combination with other disease markers) and to monitor antiviral treatment.
In histopathology, the presence of HBsAg is more commonly demonstrated by the use of the Shikata orcein technique, which uses a natural dye to bind to the antigen in infected liver cells.[1]
Positive HBsAg tests can be due to recent vaccination against Hepatitis B virus but this positivity is unlikely to persist beyond 14 days post-vaccination.[2]
History
It is commonly referred to as the Australia Antigen. This is because it was first isolated by the American research physician and Nobel Prize winner Baruch S. Blumberg in the serum of an Australian Aboriginal person.[3] It was discovered to be part of the virus that caused serum hepatitis by virologist Alfred Prince in 1968.
Heptavax, a "first-generation" hepatitis B vaccine in the 1980s, was made from HBsAg extracted from the blood plasma of hepatitis patients. Current vaccines are made from recombinant HBsAg grown in yeast.
See also
References
- ↑ Guarascio, P.; et al. (1983). "Value of copper-associated protein in diagnostic assessment of liver biopsy". Journal of Clinical Pathology. 36 (1): 18–23. doi:10.1136/jcp.36.1.18. PMC 498098. PMID 6185545.
- ↑ Rysgaard, Carolyn D; Morris, Cory S; Drees, Denny; Bebber, Tami; Davis, Scott R; Kulhavy, Jeff; Krasowski, Matthew D (2012). "Positive hepatitis B surface antigen tests due to recent vaccination: a persistent problem". BMC Clinical Pathology. 12 (1): 15. doi:10.1186/1472-6890-12-15. Retrieved 11 March 2014.
- ↑ Blumberg B, Alter H (1965). "A "new" antigen in leukemia sera". JAMA. 191: 101–106. doi:10.1001/jama.1965.03080070025007. PMID 14239025.