Genetic analysis of the human infective trypanosome, Trypanosoma brucei gambiense: chromosomal segregation, crossing over and the construction of a genetic map

Background Trypanosoma brucei is the causative agent of human sleeping sickness and animal trypanosomiasis in sub-Saharan Africa and has been subdivided into three subspecies: Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, which cause sleeping sickness in humans and the non-human infective Trypanosoma brucei brucei. T.b.gambiense is the most clinically relevant sub-species, responsible for over 90% of all human disease. The genome sequence is now available and a Mendelian genetic system has been demonstrated in T. brucei, facilitating genetic analysis in this diploid protozoan parasite. As an essential step towards identifying loci that determine important traits in the human-infective subspecies, we report the construction of a high-resolution genetic map of the STIB 386 strain of T.b.gambiense. Results The genetic map was determined using 119 microsatellite markers assigned to the 11 megabase chromosomes. The total genetic map length of the linkage groups was 733.1 centiMorgans covering a physical distance of 17.9 Megabases with an average map unit size of 24 Kilobases per centiMorgan. Forty-seven markers in this map were also used in a genetic map of the non-human infective T.b.brucei subspecies permitting comparison of the two maps and showing that synteny is conserved between the two subspecies. Conclusions The genetic linkage map presented here is the first available for the human-infective trypanosome, T.b.gambiense. In combination with the genome sequence, this opens up the possibility of using genetic analysis to identify the loci responsible for T.b.gambiense specific traits such as human infectivity as well as comparative studies of parasite field populations.