[Antigenic variation of African trypanosomes].
Although several hundred of different antigen genes exist in the trypanosome genome, only one is usually expressed at a time. This expression occurs in one of several possible telomeric expression sites. Besides being exclusively telomeric, transcription of the antigen gene exhibits other particular characteristics: the RNA polymerase is highly resistant to alpha-amanitin, and the transcription unit comprises several other genes, one of which may encode an adenylate cyclase. Post-transcriptional controls modulate the activity of this transcription unit during the parasite life-cycle. Antigenic variation is achieved through either alternative activation of different expression sites, or gene recombination within a given expression site. These mechanisms ensure a relative programming of antigen expression.
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Département de Biologie Moléculaire, Université Libre de Bruxelles, Belgique.
D000818:Animals; D000940:Antigenic Variation / Q000235:genetics*; D005786:Gene Expression Regulation; D011995:Recombination, Genetic; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000276:immunology*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000235:genetics*
D014643:Variant Surface Glycoproteins, Trypanosoma
Variation antigénique des trypanosomes africains.