However, our preliminary analysis using available L. siamensis isolates indicates that the overall mean genetic distance varied depending on the markers analyzed. The most variable marker was the ITS1 region, followed by the cyt b gene, and the hsp70 gene whereas the SSU-rRNA sequences were identical for all isolates. Sequence analysis could divide the L. siamensis isolates into two groups; the first one consisted of four isolates (isolates CU1, PCM1, PCM4, and PCM5), and the second group consisted of only one isolate (isolate

PCM2). According to these results, the isolates of groups 1 and 2 could be considered as different lineages and primarily designated as lineages PG (isolates CU1, PCM1, PCM4, and PCM5) and TR (isolate PCM2), respectively. In addition, the genetic divergence between TR and PG lineages was much RAD001 higher than usually observed within other species (data not shown). Phylogenetic analysis Three phylogenetic analyses using the NJ, MP, and Bayesian methods were performed to observe the relationships between two L. siamensis lineages. Using three different constructing methods, the trees showed similar phylogenetic topology for all four loci supported by related bootstrapping/posterior probability values. Regarding the phylogenetic tree inferred from each locus, the SSU-rRNA tree was constructed using four L. siamensis isolates and ten reference sequences of different Leishmania species

(7-Cl-O-Nec1 in vivo Figure 1a). The phylogenetic analyses grouped DZNeP chemical structure both L. siamensis lineages PG and TR together in a separated clade apart from other Leishmania species. Although lineages PG and TR were closely related according to the SSU-rRNA analysis, these Niclosamide two lineages formed separate clades in the phylogenetic tree inferred from other three markers.

The ITS1 analysis of 13 Leishmania reference sequences and 14 L. siamensis sequences revealed a close relationship of L. siamensis to the members of L. braziliensis complex by forming a strongly supported cluster with both lineages PG and TR. Moreover, L. siamensis lineage TR formed a separate branch from the lineage PG but still shared a close relationship (Figure 1b). Interestingly, L. siamensis lineage PG clustered with the reference sequences previously isolated from Thai patients (GQ226034, GQ293226, JQ001751, and JQ001752), horse (JQ617283) in USA, and those isolated from a cow (CQ281282) and horses (CQ281278, CQ281279, CQ281280, and CQ281281) in Europe. Among these isolates, 100% sequence identity was revealed, except 99.6% identity of the isolate LECU1. For the hsp70 region, the phylogenetic tree was constructed using 15 reference sequences and four L. siamensis sequences. Both L. siamensis lineages apparently formed independent monophyletic clades outside the clusters of those other species while each L. siamensis lineage was still separated into different branches (Figure 1c).