Species discrimination and phylogenetic inference of 17 Chinese Leishmania isolates based on internal transcribed spacer 1 (ITS1) sequences

Leishmaniasis is a geographically widespread disease, caused by protozoan flagellates of the genus Leishmania. This disease still remains endemic in China, especially in the west and northwest frontier regions. To date, the phylogenetic relationships among Chinese Leishmania isolates are still unclear, and the possible taxonomic diversity remains to be established. In this study, the ITS1-5.8S fragments of ten isolates collected from different foci in China were determined. To infer the phylogenetic relationships among them, seven sequences of Chinese Leishmania isolates retrieved from GenBank were also included. Both parsimony and Bayesian analyses reveal an unexpected but strongly supported clade comprising eight newly determined isolates, which is sister to other members of subgenus Leishmania. In combination with genetic distance analysis, this provides evidence of the occurrence of an undescribed species of Leishmania. Our results also suggest that (1) the isolate IPHL/CN/77/XJ771 from Bachu County, Xinjiang Uygur Autonomous Region is not Leishmania infantum but Leishmania donovani; (2) the status referring to an isolate MRHO/CN/88/KXG-2 from a great gerbil in Karamay as Leishmania turanica, formerly based on multilocus enzyme electrophoresis, is recognized; (3) an earlier finding demonstrating the L. donovani identity of isolate MHOM/CN/80/801 from Kashi city is corroborated; (4) the three isolates from eastern Jiashi County, Xinjiang Uygur Autonomous Region, causing desert type of zoonotic visceral leishmaniasis (see Wang et al., Parasitol Int (in press), 2010), belong to L. donovani instead of L. infantum. In addition, the results of this study make an important contribution to understanding the heterogeneity and relationships of Chinese Leishmania isolates, further indicating that the isolates from China may have had a more complex evolutionary history than expected.