The genome and the antigen gene repertoire of Trypanosoma brucei gambiense are smaller than those of T. b. brucei.

The amount of nuclear DNA of Trypanosoma brucei gambiense is only 70% of that of T. b. brucei. The difference is partially due to depletion of 50-150 kb mini-chromosomes in T. b. gambiense, as well as a reduction in the content of some repetitive DNA families. Quantitation of 'barren' DNA regions characteristic of the 5' environment of telomeric antigen genes confirms that the T. b. gambiense genome contains fewer chromosome ends, and thus most probably fewer telomeric antigen genes, than T. b. brucei. The extent of the antigen gene repertoire of the two subspecies has been estimated by hybridization with probes specific for the conserved 3' region of antigen genes. It appears that the repertoire of the gambiense subspecies is only about 50% of that of T. b. brucei. These observations are discussed with regard to the stability of the T. b. gambiense repertoire.