| antigenic | Having the properties of an antigen (allergen). Synonym: allergenic, immunogenic. (05 Mar 2000) |
|---|---|
| antigenic competition | Competition that occurs when two different antigens, each of which can evoke an immunological response when inoculated alone, are mixed in equal quantities and inoculated together; the response may be to only one, that to the other being largely or entirely suppressed. (05 Mar 2000) |
| antigenic complex | A composite of different antigenic structures, such as a cell or a bacterium, or, by extension, a molecule containing two or more determinant groups of different antigenic specificities. (05 Mar 2000) |
| antigenic determinant | That part of an antigenic molecule against which a particular immune response is directed. For instance a tetra to penta peptide sequence in a protein, a tri to penta glycoside sequence in a polysaccharide. In the animal most antigens will present several or even many antigenic determinants simultaneously. See: hapten. (18 Nov 1997) |
| antigenic drift | <immunology> A change that occurs on the molecular level to effect a change in the antigenicity of a bacteria or virus. Antigenic drift occurs naturally and more rapidly in certain viruses (for example HIV). It is antigenic drift which complicates the development of an effective HIV (AIDS) vaccine. (27 Sep 1997) |
| antigenic modulation | Loss of detectable antigen from the surface of a cell after incubation with antibodies. This is one method in which some tumours escape detection by the immune system. Antigenic modulation of target antigens also reduces the therapeutic effectiveness of treatment by monoclonal antibodies. (12 Dec 1998) |
| antigenic shift | Mutation, i.e., sudden change in molecular structure of RNA/DNA in microorganisms, especially viruses, which produces new strains of the microorganism; hosts previously exposed to other strains have little or no acquired immunity to the new strain; antigenic shift is believed to be the explanation for the occurrence of strains of microorganisms, such as the influenza virus, associated with large scale epidemics. (05 Mar 2000) |
| antigenic switching | <immunology> The process by which a pathogenic microbe's genetic structure is altered tochange its surface antigens inorder to avoid being detected by the host's immune system. (09 Oct 1997) |
| antigenic variation | The phenomenon of changes in surface antigens in parasitic populations of Trypanosoma and Plasmodium (and some other parasitic protozoa) in order to escape immunological defense mechanisms. at least 100 different surface proteins have been found to appear and disappear during antigenic variation in a clone of trypanosomes. Each antigen is encoded in a separate gene. Antigenic variation is also known to occur in free living Protozoa and certain bacteria. (18 Nov 1997) |
| antigenicity | <immunology> The ability of a substance to trigger an immune response in a particularorganism. (09 Oct 1997) |
| idiotypic antigenic determinant | The antigenic specificites defined by the unique sequences (idiotopes) of the antigen combining site. Thus anti-idiotype antibodies combine with those specific sequences, may block immunological reactions and may resemble the epitope to which the first antibody reacts. (18 Nov 1997) |
|---|