Unravelling the phylogenetic relationships of African trypanosomes of suids

Abstract

African trypanosomes of the subgenera Nanomonas and Pycnomonas ha\'e been recorded from both wild and domestic suids. However, complete descriptions of some of these trypanosomes with regard to host range, pathogenic, transmission and distribution are stilliackmg. Either the recently described Trypanosoma (Nannomonas) godfreyi or Trypanosoma (Nannomonas) congoiense Tsavo have been isolated from mammalian hosts, while Trypanosoma (Pyonononas) Suis remains the rarest of the Salivarian trypanosomes. The only isolate presumed to be of the latter species is maintained at the Kenya Trypanosomiasis Research Institute, Nairobi. We present here the results of characterization of this isolate by morphology, tsetse transmission, the use of species-specific DNA probes and DNA sequence analysis. Morphology in stained blood smears revealed a small trypanosome with a free flagellum. Experimental transmission through Glossinaa morsltans 1norsitans showed a developmental cycle typical of subgenus nanomonas. A positive identification was obtained with species-specific PCR primers for T. congelencese Tsavo; moreover, the sequence of the SSU rRNA gene \vas almost identical to that of T. congolense Tsavo on database. In phylogenetic analysis of the SSP rRNA genes of SaliYarian trypanosomes, T. congolense Tsavo grouped with T. simiae rather than T. congolense, suggesting that the name T. simiae Tsavo is more appropriate.