antigen

(redirected from antigenic)
Also found in: Dictionary, Thesaurus, Medical.
Related to antigenic: antigenic determinant, Antigenic drift

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 ?
We generated an antigenic map from HI data to visualize antigenic relationships among contemporary H3N2 swine IAV from multiple regions in Mexico and the United States (Figure 6, panel A).
Antigenic variations occured either when one variation occurs at a sialic acid receptor-binding site and another at an antigenic site or [greater than or equal to]2 variations occur at antigenic sites (Li et al., 2011; Shih et al., 2007).
The progression of inflammatory lesions to MF, a type of cutaneous T-cell lymphoma, showed that chronic inflammation and consequently, chronic antigenic stimulation could lead to neoplasia.
PDBsum (https://www .ebi.ac.uk/thornton-srv/ databases/cgi-bin/pdbsum/GetPage .pl?pdbcode=index.html) was used to check location of predicted conserved antigenic region in the 3D structure of D.
Serotyping is a serological procedure which separates strains of microorganisms into different groups based on their antigenic composition.
This limitation could be overcome by the use of Multiple Antigenic Peptide (MAP) (Tam and Zavala, 1989; Sadler and Tam, 2002).
As observed, sera recognized only three antigenic proteins with apparent Mr 42, 64 and 72 kDa, but some differences were observed among studied animals.
These results confirm extensive serological cross-neutralization between BoHV-1 and BoHV-5, yet indicate the existence of antigenic differences.
The phenomenon where parasite exhibits variable antigens on the surface of infected erythrocytes enables the parasite to endure and escape the host immune response known as antigenic variation.
Specific binding of antigenic peptides to a particular HLA molecule is a central problem for most of the HLA studies.
manufacturer 510(k) clearance for the first protein claim for condoms made with VNRL, less than 2 [micro]g/[dm.sup.2] of antigenic protein, potentially opening the door for other condom makers to make similar claims.
created a latex raw material called Vytex Natural Rubber Latex (NRL) that not only retains the eco-friendly nature of NRL, but significantly reduces the antigenic proteins found in natural rubber latex--the reason why some have moved away from latex.