antigenic variation


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 defence 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.

Dictionary of molecular biology. 2004.

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  • Antigenic variation — is the process by which an infectious organism alters its surface proteins in order to evade a host immune response. This change in antigenic profile may occur as the pathogen passes through a host population (also called antigenic diversity ) or …   Wikipedia

  • antigenic variation — noun (immunology) The development of new antigenic determinants by many viruses, bacteria and protozoa through genetic mutation and selection • • • Main Entry: ↑antigen …   Useful english dictionary

  • antigenic variation — 1. a mechanism whereby microorganisms or parasites, such as trypanosomes, plasmodia, and Borrelia, are enabled to escape immune surveillance of a host by modifying or completely altering their surface antigens. 2. a phenomenon occurring in the… …   Medical dictionary

  • Antigenic escape — occurs when the immune system is unable to respond to an infectious agent. Antigenic escape is the end result of Antigenic variation.One cause of Antigenic escape is that a pathogen s epitopes (the binding sites for immune cells) become too… …   Wikipedia

  • allotypic variation — the antigenic differences that characterize immunoglobulin allotypes …   Medical dictionary

  • idiotypic variation — the antigenic differences that characterize the different amino acid sequences and structures of immunoglobulin variable regions (idiotypes) and corresponding differences in antigen specificity …   Medical dictionary

  • isotypic variation — the antigenic differences that characterize the immunoglobulin classes and subclasses (isotypes) …   Medical dictionary

  • Trypanosoma brucei — Taxobox color = khaki image width = 240px image caption = Trypanosoma brucei brucei TREU667 (Bloodstream form, phase contrast picture. Black bar indicates 10 µm.) name = Trypanosoma brucei regnum = Protista phylum = Euglenozoa classis =… …   Wikipedia

  • protozoan — /proh teuh zoh euhn/, n., pl. protozoans, (esp. collectively) protozoa / zoh euh/, adj. Biol. n. 1. any of a diverse group of eukaryotes, of the kingdom Protista, that are primarily unicellular, existing singly or aggregating into colonies, are… …   Universalium

  • vaccine — Originally, the live v. (vaccinia, cowpox) virus inoculated in the skin as prophylaxis against smallpox and obtained from the skin of calves inoculated with seed virus. Usage has extended the meaning to include essentially any preparation… …   Medical dictionary


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