An isoenzyme survey of Trypanosoma brucei s.l. from the Central African subregion: population structure, taxonomic and epidemiological considerations

• Published in: Parasitology Vol. 128; no. 6; pp. 645 - 653
• Main Authors: NJIOKOU, F., NKININ, S. W., GRÉBAUT, P., PENCHENIER, L., BARNABÉ, C., TIBAYRENC, M., HERDER, S.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.06.2004
• Subjects: Africa South of the Sahara - epidemiology; African trypanosomiasis; Animals; Biological and medical sciences; Cellulose acetate; chemotaxonomy; clonal population structure; clonal variation; disease reservoirs; Drug resistance; electrophoresis; Electrophoresis, Cellulose Acetate; epidemiological studies; Fundamental and applied biological sciences. Psychology; General aspects; General aspects and techniques. Study of several systematic groups. Models; genetic distance; Genetic diversity; Genetic Variation; Hogs; Human African Trypanosomiasis; Humans; Invertebrates; Isoenzymes - genetics; isozymes; linkage disequilibrium; Linkage Disequilibrium - genetics; multilocus isoenzyme electrophoresis; Phylogeny; population structure; Standard deviation; Swine; Trypanosoma brucei; Trypanosoma brucei brucei - classification; Trypanosoma brucei brucei - enzymology; Trypanosoma brucei brucei - genetics; Trypanosoma brucei brucei - isolation & purification; Trypanosoma brucei gambiense; Trypanosoma brucei s.l; Trypanosoma brucei sensu lato; Trypanosoma gambiense; Trypanosomiasis, African - epidemiology; Trypanosomiasis, African - parasitology; zymodemes; Africa; Africa South of the Sahara; Cameroon; clonal population structure; Human African Trypanosomiasis; multilocus isoenzyme electrophoresis; Trypanosoma brucei s.l; Kinetoplastida; Human; Protozoa; Protozoal disease; Isozyme; Parasite; Population structure; Parasitosis; Infection; Electrophoresis; Trypanosoma brucei; Trypanosomiasis
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182004004974

In order to improve our knowledge about the taxonomic status and the population structure of the causative agent of Human African Trypanosomiasis in the Central African subregion, 169 newly isolated stocks, of which 16 came from pigs, and 5 reference stocks, were characterized by multilocus enzyme electrophoresis, for 17 genetic loci. We identified 22 different isoenzyme profiles or zymodemes, many of which showed limited differences between them. These zymodemes were equated to multilocus genotypes. UPGMA dendrograms revealed one main group: Trypanosoma brucei gambiense group I and 3 T. brucei ‘non-gambiense’ stocks. T. b. gambiense group I zymodemes were very homogenous, grouping all the human stocks and 31% of the pig stocks. Two main zymodemes (Z1 and Z3) grouping 74% of the stocks were found in different remote countries. The genetic distances were relatively high in T. brucei ‘non-gambiense’ zymodemes, regrouping 69% of pig stocks. The analysis of linkage disequilibrium was in favour of a predominantly clonal population structure. This was supported by the ubiquitous occurrence of the main zymodemes, suggesting genetic stability in time and space of this parasite's natural clones. However, in some cases an epidemic population structure could not be ruled out. Our study also suggested that the domestic pig was a probable reservoir host for T. b. gambiense group I in Cameroon.