Characterization and grouping of Trypanosoma brucei brucei, T.b. gambiense and T.b. rhodesiense by quantitative DNA-cytofluorometry and discriminant analysis.

For characterization and differentiation 13 stocks of Trypanosoma brucei spp. were used for a quantitative cytofluorometric determination of their DNA fluorescence intensities by two base-pair-specific fluorochromes. T. b. gambiense could be distinguished from T. b. brucei by an about 20% smaller G-C, and A-T content in the nuclear DNA and a 4% greater G-C and 15% greater A-T content of the kinetoplast DNA. T. b. gambiense could be differentiated from T. b. rhodesiense by a 20% smaller G-C and a 3.8% smaller A-T nuclear DNA content and a 2% greater G-C and a 18% greater A-T DNA content in the kinetoplast. After chromomycin (G-C specific) staining the DNA ratio kinetoplast/nucleus of T. b. gambiense was 6.8, of T. b. brucei 5.2 and of T. b. rhodesiense 5.4. The corresponding values after DAPI (A-T specific) application were 20.8 for T. b. gambiense, 14.4 for T. b. brucei and 16.6 for T. b. rhodesiense. With the fluorescence intensities a discriminant analysis has been computed. After chromomycin application the gambiense stocks could be separated from T. b. brucei and T. b. rhodesiense by this method with a hit rate of 100%. Such perfect separation could not be observed between T. b. brucei and T. b. rhodesiense. Even if most of them were classified into the corresponding subgroups some trypanosomes would nevertheless pass over into the brucei or rhodesiense subgroup and vice versa.(ABSTRACT TRUNCATED AT 250 WORDS)