The five tests for hepatitis B are preliminary tests used to determine whether you are infected with hepatitis B and to roughly estimate the level of viral replication, although the items are few and the tests are simple, the significance is very important. The five tests for hepatitis B are: 1. surface antigen (HBSAg); 2. surface antibody (anti-HBs); 3. е antigen (HBeAg); 4. е antibody (anti-HBe); 5. core antibody (anti-HBc). The five hepatitis B tests are also called hepatitis B two-and-a-half. 1, HBsAg – surface antigen: is the shell protein of the hepatitis B virus, itself is not infectious, but its appearance is often accompanied by the presence of the hepatitis B virus, so it is a sign of having been infected with the hepatitis B virus. Clinical Significance: It is a sign that the virus has been infected, and does not reflect the strength of viral replication or infectiousness. Hepatitis B surface antigen titer is not necessarily related to the severity of liver disease Hepatitis B surface antigen (HBsAg) titer indicates the amount of HBsAg in the serum. High titers of HBsAg often indicate high levels of viral replication; low titers of HBsAg may be due to low viral replication during recovery from infection, or partial clearance of virus and antigen during inflammatory activity; in a few cases, it is due to viral mutation, causing changes in HBsAg antigenicity and thus reduced affinity for reagent antibodies, manifesting as low titers of HBsAg on clinical examination. 2, HBsAb-surface antibody: generally referred to as surface antibody. When the hepatitis B virus invades the body, stimulates the human immune system to produce an immune response, the human immune system in the B lymphocytes secrete a specific immunoglobulin G. It can specifically bind with the surface antigen, in the body and the body’s other immune function together, the virus can be removed to protect the body from further infection by the hepatitis B virus, so called surface antibodies for protective antibodies. Clinical significance: a neutralizing antibody marker, the main sign of recovery or resistance. 3, e antigen (HBeAg): generally known as e antigen. It originates from the core of hepatitis B virus and is a subcomponent of core antigen or a product of core antigen cleavage. e antigen is a soluble protein. When the core antigen is cleaved, the soluble protein fraction (i.e., e antigen) dissolves in the serum and is present in the circulation, and can be detected if blood is taken for testing. Clinical significance: as a marker of viral replication, persistently positive for more than 3 months, then there is a tendency to chronicity. 4, HBeAb-e antibody: e antibody is the abbreviation of hepatitis B e antibody (anti-HBe), which is a specific antibody produced by the human immune system stimulated by e antigen, this specific e antibody can bind with e antigen. Clinical significance: a sign of viral replication cessation, reduced viral replication and weaker infectivity, but anti-HBe is different from anti-HBs. e antibody is not a protective antibody and does not mean that the patient has immunity. 5, HBcAb-core antibody: although the core antigen is not detected in the serum (it is quickly cleaved in the blood), but it is antigenic and can stimulate the body’s immune system to produce characteristic antibodies, that is, core antibodies, so the detection of anti-HBc can understand whether the body has had the stimulation of core antigen, that is, whether there has been hepatitis B virus infection. Therefore, anti-HBc is a marker of viral infection. Clinical significance: a marker of previous infection or the presence of a period of infection. Core antibody IGM is a marker of recent infection or viral replication, and core antibody IgG is produced right after infection, and is of some significance in aiding the two-to-one half test.