(redirected from HBsAg)
Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


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.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.


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

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


A substance which reacts with the products of specific humoral or cellular immunity, even those induced by related heterologous immunogens.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


a substance that stimulates the production of antibodies
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Tedavi kesilmesinde gozetilen sonlanim noktasi HBsAg kaybidir ki, oldukca az hastada ulasilabilen bir durumdur.
(26) reported a similar increase in the rate of anti-HBs and decrease in the rate of HBsAg in their study conducted on pregnant women over a 20-year period.
In this study, co-infection of HBsAg and HCV was observed in 0.096% (11/11399).
HBsAg responses observed with ARO-HBV are consistent with the ability of ARO-HBV to silence HBV mRNA from cccDNA and host-integrated viral DNA, a major source of HBsAg in certain patient populations (Wooddell, 2018)
Nevertheless, in clinical practice in China, where HBsAg may be detected among 25-61% of patients with DLBCL, the risk of HBV reactivation and the management of HBV infection during R-chemo treatment remain significant concerns.
Among 273 household contacts of HBsAg-positive participants, 39 (14%) had positive test results for HBsAg, 83 (30%) had negative test results for HBsAg and positive results for anti-HBc (immune because of resolved infection), and 101 (37%) were anti-HBs-positive and anti-HBc-negative (immune because of vaccination).
Association between participant characteristics and outcome variables (HBsAg positivity) was assessed using [chi square] test (or Fisher's exact test as appropriate) for categorical predictors.
As indicated in Figure 5, the results of age to virologic relapse (Figure 5(a)), the level of HBsAg to virologic relapse (Figure 5(b)), and the level of HBsAg to clinical relapse (Figure 5(c)) all showed significant diagnostic effectiveness (all p < 0.05).
In a study done by Butt and Amin (2008), the prevalence of both of the infections, 1.7% anti-HCV and 2.93% HBsAg were estimated in young adults14.
Sera were collected from these samples and were screened for HBsAg and Anti HCV using immunochromatography technique (ICT) in the PMRC (Pakistan Medical Research Council) labs of Khyber Medical College Peshawar.
Immunsuppresif tedavi planlanan hastalarda tedavi oncesinde HBV serolojisi (HBsAg ve Anti-HBc (hepatit B kor antijen antikoru) ile) bakilmasi nerdeyse tum kliniklerde rutin hale gelmistir (4).
The sample size calculation was based on expected HBsAg prevalence extrapolated from the 2006 survey by age group (0.7% for 1-4 years, 1.5% for 5-14 years, and 5.0% for 15-29 years) and was powered to detect differences of [+ or -]50% the expected point prevalence.