[[File:HepB Assay Results.jpg|thumb|center|700px|Hepatitis B assay results <SMALL> Adapted from ''[http://www.who.int/en/ World Health Organization]''<ref>{{Cite web | title = http://www.who.int/en/ | url = http://www.who.int/en/}}</ref></SMALL>]]
[[File:HepB Assay Results.jpg|thumb|center|700px|Hepatitis B assay results <SMALL> Adapted from ''[http://www.who.int/en/ World Health Organization]''<ref>{{Cite web | title = http://www.who.int/en/ | url = http://www.who.int/en/}}</ref></SMALL>]]
===Antigens===
====HBsAg====
Hepatitis B surface antigen is the earliest indicator of acute infection and is also indicative of chronic [[infection]] if its presence persists for more than 6 months. It is useful for the diagnosis of [[HBV]] infection and for [[screening]] of blood. Its specific [[antibody]] is anti-HBs. [[HBsAg]] indicates that the person is potentially [[infectious]].
====HBcAg====
Hepatitis B core antigen is derived from the protein envelope that encloses the [[viral]] DNA, and it is not detectable in the [[bloodstream]]. When HBcAg peptides are expressed on the surface of [[hepatocytes]], they induce an [[immune]] response that is crucial for killing infected cells. The HBcAg is a marker of the infectious viral material and it is the most accurate index of [[viral replication]]. Its specific [[antibody]] is anti-HBc.
====HBeAg====
Hepatitis B e antigen appearing during weeks 3 to 6 indicates an acute active infection at its most [[infectious]] period, and means that the patient is [[infectious]]. Persistence of this virological marker beyond 10 weeks shows progression to chronic infection and infectiousness. Continuous presence of anti-HBe indicates chronic or chronic active liver disease. HBeAg is not incorporated into [[virions]], but is instead secreted into the [[serum]]. Mutant strains of HBV exist that replicate without producing HBeAg. HBeAg’s function is uncertain. Its specific [[antibody]] is anti-HBe.
====HBxAg====
Hepatitis B x antigen is detected in HBeAg positive blood in patients with both acute and chronic hepatitis. HBxAg is a transcriptional activator. It does not bind to [[DNA]]. Its specific [[antibody]] is anti-HBx.
====HBV DNA====
HBV DNA is detectable by PCR as soon as 1 week after initial infection, but the test is generally only performed for research purposes or to detect mutants that escape detection by current methods.
====HBV DNA Polymerase====
Tests for the presence of [[HBV]] [[DNA polymerase]], detectable within 1 week of initial infection, are only performed for research purposes.
===Antibodies===
====Anti-HBs====
This is the specific [[antibody]] to hepatitis B surface antigen. Its appearance 1 to 4 months after onset of [[symptoms]] indicates clinical recovery and subsequent immunity to HBV. Anti-HBs can neutralize HBV and provide protection against HBV infection.
====Anti-HBc====
This is the specific [[antibody]] to hepatitis B core antigen. [[Antibodies]] to HBc are of class IgM and IgG. They do not neutralize the [[virus]]. The presence of [[IgM]] identifies an early acute [[infection]]. In the absence of [[HBsAg]] and anti-HBs, it shows recent [[infection]]. IgG with no IgM may be present in chronic and resolved infections. Anti-HBc testing identifies all previously infected persons, including [[HBV]] carriers, but does not differentiate carriers and non-carriers.
====Anti-HBe====
This is the specific [[antibody]] to hepatitis B e antigen. During the acute stage of infection the [[seroconversion]] from e antigen to e antibody is [[prognostic]] for resolution of [[infection]]. Its presence in the patient’s blood along with anti-HBc and in the absence of HBsAg and anti-HBs indicates low contagiousness and convalescence.
====Anti-HBx====
This is the specific [[antibody]] to hepatitis B x antigen. It appears when other [[virus|virological]] markers are becoming undetectable.
The three standard blood tests for hepatitis B can determine if a person is currently infected with HBV, has recovered, is a chronic carrier, or is susceptible to HBV infection:[1]
