Multiple events associated with antigenic switching in Trypanosoma brucei

• Published in: Molecular and biochemical parasitology Vol. 29; no. 2; pp. 227 - 241
• Main Authors: Myler, Peter J., Aline, Robert F., Scholler, John K., Stuart, Kenneth D.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 01.06.1988; Elsevier Science
• Subjects: Animals; Antigenic Variation; Antigens, Protozoan - genetics; Biochemistry. Physiology. Immunology. Molecular biology; Biological and medical sciences; Chromosome Mapping; DNA - analysis; DNA Restriction Enzymes; Electrophoresis, Agar Gel; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genomic rearrangements; Human protozoal diseases; Infectious diseases; Medical sciences; Nucleic Acid Hybridization; Parasitic diseases; Protozoa; Protozoal diseases; Tropical medicine; Trypanosoma brucei; Trypanosoma brucei brucei - genetics; Trypanosoma brucei brucei - immunology; Trypanosomiasis; Variant Surface Glycoproteins, Trypanosoma - genetics; Genomic rearrangements; BC; PFGE; Antigenic variation; kb; VAT; VSG; Trypanosoma brucei; ELC; DC; Antigen; Protozoa; Gene rearrangement; Rhizoflagellata; Pathogen
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/0166-6851(88)90078-3

The genomic environments of six unrelated variant surface glycoprotein (VSG) gene families in the IsTaR 1 serodeme of Trypanosoma brucei were examined by Southern blot analysis of DNA resolved by conventional and pulse field gradient electrophoresis. The genomic locations of these gene family members were characterized in variants arising from 19 independent antigenic switches of which 13 represent single relapses. We have identified 9 distinct telomeric sites containing VSG genes on 7 different chromosomes ranging in size from ∼65 kilobase pairs to > 3 megabase pairs. VSG genes are expressed in at least 6 of these telomeric sites. All of the observed antigenic switches can be explained by two types of processes: gene conversion and telomeric activation, with almost half ( 9 19 ) the result of combinations of these processes. The implications of these observations are discussed with particular reference to the frequencies of occurrence of each process.