Phylogenetic analysis of HSP70 and cyt b gene sequences for Chinese Leishmania isolates and ultrastructural characteristics of Chinese Leishmania sp.

Leishmaniasis is a worldwide epidemic disease caused by the genus Leishmania, which is still endemic in the west and northwest areas of China. Some viewpoints of the traditional taxonomy of Chinese Leishmania have been challenged by recent phylogenetic researches based on different molecular markers. However, the taxonomic positions and phylogenetic relationships of Chinese Leishmania isolates remain controversial, which need for more data and further analysis. In this study, the heat shock protein 70 (HSP70) gene and cytochrome b (cyt b) gene were used for phylogenetic analysis of Chinese Leishmania isolates from patients, dogs, gerbils, and sand flies in different geographic origins. Besides, for the interesting Leishmania sp. in China, the ultrastructure of three Chinese Leishmania sp. strains (MHOM/CN/90/SC10H2, SD, GL) were observed by transmission electron microscopy. Bayesian trees from HSP70 and cyt b congruently indicated that the 14 Chinese Leishmania isolates belong to three Leishmania species including L. donovani complex, L. gerbilli, and L. (Sauroleishmania) sp. Their identity further confirmed that the undescribed Leishmania species causing visceral Leishmaniasis (VL) in China is closely related to L. tarentolae. The phylogenetic results from HSP70 also suggested the classification of subspecies within L. donovani complex: KXG-918, KXG-927, KXG-Liu, KXG-Xu, 9044, SC6, and KXG-65 belong to L. donovani; Cy, WenChuan, and 801 were proposed to be L. infantum. Through transmission electron microscopy, unexpectedly, the Golgi apparatus were not observed in SC10H2, SD, and GL, which was similar to previous reports of reptilian Leishmania. The statistical analysis of microtubule counts separated SC10H2, SD, and GL as one group from any other reference strain (L. donovani MHOM/IN/80/DD8; L. tropica MHOM/SU/74/K27; L. gerbilli MRHO/CN/60/GERBILLI). The ultrastructural characteristics of Leishmania sp. partly lend support to the phylogenetic inference that Chinese Leishmania sp. is in close relationship with reptilian Leishmania.