antigen

(redirected from hepatitis B surface antigen)
Also found in: Dictionary, Thesaurus, Medical, Acronyms.
Related to hepatitis B surface antigen: hepatitis B core antigen

antigen:

see immunityimmunity,
ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.
..... Click the link for more information.
.

Antigen

A substance that initiates and mediates the formation of the corresponding immune body, termed antibody. Antigens can also react with formed antibodies. Antigen-antibody reactions serve as host defenses against microorganisms and other foreign bodies, or are used in laboratory tests for detecting the presence of either antigen or antibody. See Antibody, Antigen-antibody reaction

A protein immunogen (any substance capable of inducing an immune response) is usually composed of a large number of antigenic determinants. Thus, immunizing an animal with a protein results in the formation of a number of antibody molecules with different specificities. The antigenicity of a protein is determined by its sequence of amino acids as well as by its conformation. Antigens may be introduced into an animal by ingestion, inhalation, sometimes by contact with skin, or more regularly by injection into the bloodstream, skin, peritoneum, or other body part.

With a few exceptions, such as the autoantigens and the isoantigens of the blood groups, antigens produce antibody only in species other than the ones from which they are derived. All complete proteins are antigenic, as are many bacterial and other polysaccharides, some nucleic acids, and some lipids. Antigenicity may be modified or abolished by chemical treatments, including degradation or enzymatic digestion; it may be notably increased by the incorporation of antigen into oils or other adjuvants. See Isoantigen

Bacteria, viruses, protozoans, and other microorganisms are important sources of antigens. These may be proteins or polysaccharides derived from the outer surfaces of the cell (capsular antigens), from the cell interior (the somatic or O antigens), or from the flagella (the flagellar or H antigens). Other antigens either are excreted by the cell or are released into the medium during cell death and disruption; these include many enzymes and toxins, of which diphtheria, tetanus, and botulinus toxins are important examples. The presence of antibody to one of these constituent antigens in human or animal sera is presumptive evidence of past or present contact with specific microorganisms, and this finds application in clinical diagnosis and epidemiological surveys. See Botulism, Diphtheria, Toxin

Microbial antigens prepared to induce protective antibodies are termed vaccines. They may consist of either attenuated living or killed whole cells, or extracts of these. Since whole microorganisms are complex structures, vaccines may contain 10 or more distinct antigens, of which generally not more than one or two engender a protective antibody. Examples of these are smallpox vaccine, a living attenuated virus; typhoid vaccine, killed bacterial cells; and diphtheria toxoid, detoxified culture fluid. Several independent vaccines may be mixed to give a combined vaccine, and thus reduce the number of injections necessary for immunization, but such mixing can result in a lesser response to each component of the mixture. See Vaccination

Allergens are antigens that induce allergic states in humans or animals. Examples are preparations from poison ivy, cottonseed, or horse dander, or simple chemicals such as formaldehyde or picryl chloride. See Hypersensitivity, Immunology

antigen

[′an·tə·jən]
(immunology)
A substance which reacts with the products of specific humoral or cellular immunity, even those induced by related heterologous immunogens.

antigen

a substance that stimulates the production of antibodies
References in periodicals archive ?
Site-directed mutagenesis of cysteine residues of hepatitis B surface antigen.
Structural characterization of viral neutralizing monoclonal antibodies to hepatitis B surface antigen.
Localization of hepatitis B surface antigen epitopes present on variants and specifically recognized by antihepatitis B surface antigen monoclonal antibodies.
The same treatement regimen would apply if the patient's blood is negative for hepatitis B surface antigen but positive for core antibody and the employee's titer is less than or equal to 10.
Contract awarded for Hepatitis b surface antigen, reagent for the determination
Hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were detected in 370 of 11,893 men with hepatitis B infections.
The trial was designed to test this approach as an alternative to expensive treatment with antibodies against hepatitis B surface antigen, which are used to prevent reinfection in patients transplanted due to hepatitis B virus-related cirrhosis.
Individuals may also seroconvert to hepatitis B surface antigen (HBsAg), which is a more definitive indicator of long-term viral clearance and clinical remission.
HEPLISAV merges hepatitis B surface antigen with a Toll-like Receptor 9 agonist to boost the immune response.
Chronic and unexplained hepatitis, despite a negative test for hepatitis B surface antigen, may still be the result of hepatitis B infection, reported Dr.
Using a protocol similar to that of the TSH assay, an assay for hepatitis B surface antigen (HBsAg) was established to achieve the high sensitivity demanded of this assay when used for blood-quality screening.
The intact hepatitis B core structures are highly immunogenic, eliciting much stronger humoral and cellular responses than vaccines containing hepatitis B surface antigens.

Full browser ?