Application of multiple DNA fingerprinting techniques to study the genetic relationships among three members of the subgenus Trypanozoon (Protozoa: Trypanosomatidae)

Abstract

Three different DNA fingerprinting techniques, the mobile genetic element (MGE)-PCR, simple sequence repeat (SSR)-PCR and random amplified polymorphic DNA (RAPD)-PCR, were used to define a large set of genetic markers to study genetic similarity within and among Trypanosoma brucei, Trypanosoma equiperdum and Trypanosoma evansi strains (n=18) from China, Africa and South America and to investigate their genetic relationships. Using the three fingerprinting techniques, >890 bands (ranging in size from 0.2 to 2kb) were defined for all 18 strains of Trypanosoma. Within each of the strains, 39-59 bands were defined. The similarity coefficients between strains ranged from approximately 41 to 94%, with a mean of 65%. There was more genetic similarity among strains within T. evansi (mean of approximately 79%) compared with T. equiperdum ( approximately 65%) and T. brucei ( approximately 59%). The similarity coefficient data were used to construct the dendrogram, which revealed that (irrespective of species) the majority of strains from China and South America grouped together to the exclusion of those from Africa. The exceptions were a T. brucei strain from Africa and a T. equiperdum strain of unknown origin. Hence, employing data sets generated using the three different fingerprinting methods, it was not possible to unequivocally distinguish among T. brucei, T. evansi and T. equiperdum, although there was a tendency for T. evansi strains to group together to the exclusion of T. brucei. The findings provide support for the hypothesis that T. evansi originated from a mutated form of T. equiperdum and stimulate further investigations of the genetic make-up and evolution of members of the subgenus Trypanozoon.