Molecular Identification and Intra-species Variations among Leishmania infantum Isolated from Human and Canine Visceral Leishmaniasis in Iran

BACKGROUND: In Iran, both forms of cutaneous (CL) and visceral leishmaniasis (VL) have been re-ported; so the accurate species identification of the parasite(s) and the analysis of genetic diversity are necessary. METHODS: The investigation was conducted from 2014 to 2015 in the northwest and south of Iran, where VL is endemic (7 provinces). Blood samples of patients and infected dogs were collected and sera separated for serologic examinations (DAT, rK39). Spleen or bone marrow samples from infected dogs were also collected to confirm the infection. DNAs of 70 samples amplified by targeting a partial sequence of ITS (18S rRNA–ITS1–5.8S rRNA–ITS2) gene. All the amplicons were sequenced and analyzed with restriction fragment length polymorphism (RFLP) using the TaqI enzyme. RESULTS: The cause of all 70 VL cases, were L. infantum, so, the dominant specie is L. infantum. The sequencing results of all VL cases and RFLP analysis corroborate each other. Discrimination of Iranian Leishmania isolates using ITS gene gives us this opportunity to detect, identify and construct the phylogenetic relationship of Iranian isolates. In addition, detection and differentiation of Leishmania spp. DNA was confirmed by amplification of variable area of the minicircle kDNA (conserved sequence blocks (CSB)). CONCLUSION: Low divergence and high likelihood were seen among L. infantum isolates of human and dogs from Iran with a very slight divergence was seen between isolates from northwest and south of Iran, thus grouped in a unique clad. No correlation was observed between intraspecies divergence and geographic distribution of the isolates.