Biomaterial Database

Control of antigenic variation in African trypanosomes. 1991

L H Van der Ploeg

Department of Genetics and Development, Columbia University, New York, NY 10032.

Antigenic variation of African trypanosomes results from the controlled expression of a single variant cell-surface glycoprotein (VSG) gene from a repertoire of about 1,000 genes. The transcription of the VSG genes occurs uniquely at telomeres, where the expressed VSG gene is part of a large polycistronic transcription unit that appears to be transcribed by a specialized RNA polymerase. Recent developments that enhanced our understanding of the control of VSG gene expression and of the mechanisms of antigenic variation are discussed in this review.

UI	MeSH Term	Description	Entries
D012045	Regulatory Sequences, Nucleic Acid	Nucleic acid sequences involved in regulating the expression of genes.	Nucleic Acid Regulatory Sequences,Regulatory Regions, Nucleic Acid (Genetics),Region, Regulatory,Regions, Regulatory,Regulator Regions, Nucleic Acid,Regulatory Region,Regulatory Regions
D005786	Gene Expression Regulation	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.	Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D005812	Genes, Switch	Genes that cause the epigenotype (i.e., the interrelated developmental pathways through which the adult organism is realized) to switch to an alternate cell lineage-related pathway. Switch complexes control the expression of normal functional development as well as oncogenic transformation.	Switch Genes,Switching Complex,Switch Complexes,Switching Complexes,Complex, Switching,Complexes, Switch,Complexes, Switching,Gene, Switch,Switch Gene
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000940	Antigenic Variation	Change in the surface ANTIGEN of a microorganism. There are two different types. One is a phenomenon, especially associated with INFLUENZA VIRUSES, where they undergo spontaneous variation both as slow antigenic drift and sudden emergence of new strains (antigenic shift). The second type is when certain PARASITES, especially trypanosomes, PLASMODIUM, and BORRELIA, survive the immune response of the host by changing the surface coat (antigen switching). (From Herbert et al., The Dictionary of Immunology, 4th ed)	Antigen Switching,Antigenic Diversity,Variation, Antigenic,Antigen Variation,Antigenic Switching,Antigenic Variability,Switching, Antigenic,Diversity, Antigenic,Switching, Antigen,Variability, Antigenic,Variation, Antigen
D000953	Antigens, Protozoan	Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.	Protozoan Antigens
D014158	Transcription, Genetic	The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.	Genetic Transcription
D014347	Trypanosoma brucei gambiense	A hemoflagellate subspecies of parasitic protozoa that causes Gambian or West African sleeping sickness in humans. The vector host is usually the tsetse fly (Glossina).	Trypanosoma gambiense,Trypanosoma brucei gambienses,Trypanosoma gambienses,brucei gambiense, Trypanosoma,brucei gambienses, Trypanosoma,gambiense, Trypanosoma brucei,gambienses, Trypanosoma
D014643	Variant Surface Glycoproteins, Trypanosoma	Glycoproteins attached to the surface coat of the trypanosome. Many of these glycoproteins show amino acid sequence diversity expressed as antigenic variations. This continuous development of antigenically distinct variants in the course of infection ensures that some trypanosomes always survive the development of immune response to propagate the infection.	Surface Variant Glycoproteins, Trypanosoma,Trypanosoma Variant Surface Coat Glycoproteins,SSP-4,VSG 117,VSG 118,VSG 221
D015321	Gene Rearrangement	The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.	DNA Rearrangement,DNA Rearrangements,Gene Rearrangements,Rearrangement, DNA,Rearrangement, Gene,Rearrangements, DNA,Rearrangements, Gene