Evolutionary history and molecular phylogeny of Babesia parasites

SCHNITTGER L; RODRIGUEZ AE; FLORIN-CHRISTENSEN M; MORRISON DA

Congreso; 13th International Congress of Parasitology (ICOPA); 2014

Evolutionary history and molecular phylogeny of BabesiaBACKGROUND: Piroplasmids are tick-transmitted hemoprotozooans which infectmammals and birds. They are acknowledged for their major impact on farm and petanimal health and associated economic costs worldwide. Human babesiosis, alsotransmitted by blood transfusion, is an increasing public health concern. Piroplasmidsrepresent an apicomplexan group that consists of the closely related Babesia,Cytauxzoon and Theileria parasites.METHODS: Over six hundred 18S rRNA gene sequences were aligned based onhomology criteria and secondary structure models to construct a bayesian phylogenetictree.RESULTS: We present a thoroughly revised molecular classification, comprising of fivemonophyletic Babesia lineages, one Cytauxzoon clade, and one Theileria clade.Notably, Babesia lineages constitute a paraphyletic assemblage calling for a change ofgenus name for at least four of these lineages. Monophyly of Cytauxzoon speciescould be confirmed. Theileria youngi and T. bicornis are demonstrated to representBabesia species. T. equi, formerly: Babesia equi, is shown to be neither a Theileria nora Babesia species but to belong to a separate piroplasmid clade. Each of three birdinfectingBabesia species represent a sister taxon to different Babesia clades.Furthermore, seven Babesia species belonging to three unrelated clades have beenreported to infect humans.CONCLUSIONS: Babesia species infecting birds may have played an important role inthe dissemination of the parasite at an early timeframe of piroplasmid evolution.Babesia species infecting humans belong to at least three unrelated monophyleticlineages. A more widespread taxon sampling will allow to further advance Babesiaphylogeny and taxonomy.Financed by CONICET, INTA (PNBIO-1131034) and ANPCyT (PICT 2010-0438) andEC (INCO245145)