Enzyme-Linked Immunosorbent Assay for qualitative or quantitative determination of Hepatitis B surface Antibody (Anti-HBs) in human serum or plasma
In 1965, Dr. Blumberg who was studying hemophilia, found an antibody in two patients which reacted against an antigen from an Australian Aborigine. Later the antigen was found in patients with serum type hepatitis and was initially designated "Australian Antigen". Subsequent study has shown the Australian Antigen to be the hepatitis B surface antigen (HBsAg, HBs Antigen). Initially there appeared to be three particles associated with hepatitis B infection: a large "complete" particle called the "Dane particle", a small circular 22 nm particle and an oblong 42 nm C particle. Further research identified the Dane particle as the hepatitis B virion and the other two particles as excess surface protein. This former terminology is no longer used and the virus is referred to according to its structure. Subsequent association with hepatitis B virus (HBV) led to the development of sensitive, specific markers of HBV infection. During acute and chronic HBV infection, HBsAg is produced in excess amounts, circulating in blood as both 22 nm spherical and tubular particles. HBsAg can be identified in serum 30~60 days after exposure to HBV and persists for variable periods depending on the resolution of the infection. Antibody to HBsAg (anti-HBs) develops after a resolved infection and is responsible for long-term immunity. Anti-HBc develops in both resolved acute infections and chronic HBV infections and persists indefinitely. Immunoglobulin M (IgM) anti-HBc appears early in infection and persists for greater than or equal to 6 months. It is a reliable marker of acute HBV infection.
** Modes of Transmission: Transmission of HBV occurs via percutaneous or permucosal routes, and infective blood or body fluids can be introduced at birth, through sexual contact or by contaminated needles. Infection can also occur in settings of continuous close personal contact (such as in households or among persons in institutions for the developmentally disables), presumably via inapparent or unnoticed contact of infective secretions with skin lesions or mucosal surfaces.
Testing for antibodies against Hepatitis B surface antigen (Anti-HBs), the last marker to appear in seroconversion, is an important tool in evaluating recovery from Hepatitis B Virus infection and also for screening of populations undergoing immunization programs. Generally Anti-HBs appears in serum at the end of the "window" period, following HBsAg clearance, after which they may persist for years or for a lifetime. A lack of seroconversion into Anti-HBs indicates that the patient is evolving into chronic hepatitis (5% of infection cases).