Search results
Results from the WOW.Com Content Network
The genome organisation of HBV; the genes overlap. ORF S, in green, encodes HBsAg. 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.
The time between the removal of the HBsAg and the appearance of anti-HBs is called the window period. A person negative for HBsAg but positive for anti-HBs either has cleared an infection or has been vaccinated previously. Individuals who remain HBsAg positive for at least six months are considered to be hepatitis B carriers. [68]
HBsAg (hepatitis B surface antigen) was the first hepatitis B virus protein to be discovered. [15] It consists of small (S), medium (M) and large (L) protein. [16] HBcAg (hepatitis B core antigen) is the main structural protein of HBV icosahedral nucleocapsid and it has function in replication of the virus. [17]
It is an indicator of active viral replication; this means the person infected with Hepatitis B can likely transmit the virus on to another person (i.e. the person is infectious). HBeAg is considered a marker for cccDNA replication.
The HBV has four genes: S, P, C, and X. The S gene codes for the "major" envelope protein (HBsAg). The largest gene is P. It codes for DNA polymerase. The C gene codes for HBeAg and HBcAg. The C gene has a precore and a core region. If translation is initiated at the precore region, the protein product is HBeAg.
If HBsAg is present, a second test – usually done on the same blood sample – that detects the antibody for the hepatitis B core antigen (anti-HBcAg) can differentiate between acute and chronic infection. [84] [88] People who are high-risk whose blood tests negative for HBsAg can receive the hepatitis B vaccine to prevent future infection.
An individual with a chronic infection would test positive for HBsAg and total anti-HBc (IgM and IgG), but negative for IgM anti-HBc and anti-HBs. An individual who has successfully resolved their HBV infection will test negative for HBsAg, positive for anti-HBc, and may test negative or positive for anti-HBs, although most will test positive ...
It is produced by yeast cells, into which the gene for HBsAg has been inserted. [65] Afterward an immune system antibody to HBsAg is established in the bloodstream. The antibody is known as anti-HBs. This antibody and immune system memory then provide immunity to hepatitis B virus (HBV) infection. [71]