Phylogenetic analysis of Cysteine-Proteases sequences of Tritrichomonas foetus: crossing the species barrier?

Objectives. To analyze the cysteine-protease (CP) gene sequences of Tritrichomonas spp. reported in GenBank, and develop a phylogenetic analysis to help clarify the possibility of transmission between species. Materials and Methods. The CP sequences of Tritrichomonas spp. available in GenBank were analyzed and aligned to identify polymorphic sites. The best nucleotide substitution model was determined, and phylogenetic trees were constructed for each gene, using Trichomonas vaginalisas an outgroup. Besides, tandem sequences of each reported pathogen were constructed to build phylogenetic trees with higher branch strength. Finally, the evolutionary divergence of the tandem repeat sequences was estimated to obtain more conclusive results. Results. The phylogenetic analysis showed the relationship that may exist between porcine T. suis and bovine T. foetus. The feline and bovine T. foetus sequences were found in separate groups; however, feline T. foetus was similar to that of bovines from Namibia. The proximity of human T. foetus to bovine and porcineT. foetus was verified. Conclusions. Phylogenetic analysis of CP sequences in different species of Tritrichomonas spp., identified relationships between bovine, porcine and human Tritrichomonas, but also between some isolated feline sequences with those of bovines, suggesting a possibility of barrier crossing between species.