Applying a cytochrome c oxidase I barcode for Leishmania species typing

Species delimitation has always been a challenge for taxonomists and for Leishmania studies there is no exception. Herein we attempt to display the usefulness of the mitochondrial gene Cytochrome Oxidase I-coI in classical and barcode-based approaches for Leishmania characterization. A total of 228 samples were analyzed, comprising 28 Leishmania related taxa, mainly from cultures of the Oswaldo Cruz Foundation`s Leishmania Collection. Primers were designed for amplification of coI; sequences were analyzed by distance-based indicators and both the Neighbor Joining and NeighborNet as species grouping techniques. Automatic Barcode Gap Discovery was applied to define species delimitation while for the character-based analysis a software for Barcoding with Logic formulas was employed. Final sequences of 486 bp with 238 parsimonious sites were aligned and edited. Robust groups were formed for most of the genus species, distinctive nucleotide positions in the barcode sequence were observed for 11 of them. A good agreement between the techniques applied and the original characterization was observed. Few species were not distinguished by coI: (i) L. (V.) peruviana, L. (V.) lindenbergi, and L. (V.) utingensis; (ii) L. (L.) venezuelensis and (iii) L. colombiensis and L. equatorensis with identical sequences. Some of these taxa have been, at one time or another, classified as controversial and, for most of them, a higher number of isolates should be studied to properly infer their taxonomic status. CoI represents a mitochondrial target that stands out as a taxonomically important asset with multiple advantages over other genes. This paper corresponds to the first report of coI analysis in Leishmania, a potentially advantageous target for the characterization of this parasite.