Diversidade, taxonomia e filogenia de tripanossomatídeos da subfamilia Leishmaniinae.

Abstract

The Leishmaniinae subfamily trypanosomatids include parasites exclusively found in insects, and classified as Crithidia and Leptomonas, and species evolving in vertebrate and insects of genera Endotrypanum and Leishmania. Phylogenetic analysis positioned Crithidia and Leptomonas species in several clades corroborating their polyphyly. In addition, the genus Endotrypanum of trypanosomatids from sloths and sand flies has been questioned due to its relationships with some "enigmatic", Neotropical species of Leishmania (mostly of wildlife). Therefore, Crithidia, Leptomonas and Endotrypanum need to be revised taxonomically. Aiming to understand the phylogenetic relationships of taxons within Leishmaniinae the main goals of this study were: a) to characterize a large number of Leishmaniinae isolates; b) to evaluate the suitability of different molecular markers to assess the relationships among species separated by small genetic distances. With these purposes, large sampling of trypanosomatids from insects (Hemiptera and Diptera) and wild vertebrates from Central America (CA), South America (SA) and Africa (AF) was analyzed by V7V8 SSUrRNA barcoding. All samples assigned to Leishmaniinae were selected for phylogenetic inferences based on SSUrRNA, gGAPDH, CATB, HSP70 and ITS1rDNA, including other sequences available in databanks. Phylogeny of SSUrRNA revealed several groups despite high degrees of sequence conservation inter-and intra-group. In contrast, gGAPDH and CATB gene analyses allowed the positioning of Leishmaniinae species in well-supported clades, with two major clades being evidenced in all analyses: 1) one clade comprised exclusively trypanosomatids of insects distributed in 7 subclades, each corresponding to one genus, including Crithidia, Leptomonas, Legeria (proposed in this work), and four unnamed additional genera. The species within these genera were widespread in a range of insects: Crithidia harbored parasites of flies, mosquitoes and hemipterans from SA and NA (North America); Legeria isolates of flies and hemipterans from AF, CA and SA; and Leptomonas only isolates of hemipterans from AF, CA and SA. 2) The proposed new genus Legeria was closest to the second major clade. The latter harbored Leishmania/Endotrypanum and the basal Costarricensis group comprised by equatorial parasites from hemipteran predators and sand flies, thus supporting the origin of Leishmania from a Neotropical insect trypanosomatid. Diverse isolates of lyzards, including new species from AF (Mozambique), were all nested into the subgenera L. (Sauroleishmania), which was positioned with strong support closer to the subgenus L. (Leishmania) than to Viannia, then supporting that lizard leishmanias diverged in the Old World. The three subgenera were separated from another clade formed by Neotropical isolates of sandflies, sloths and humans classified as Endotrypanum and Leishmania, with L. deanei/L.hertigi of porcupines as basal species. The comprehensive analysis performed in this study regarding the number and diversity of isola...