Genetic diversity and haplotype analysis of Leishmania tropica identified in sand fly vectors of the genera Phlebotomus and Sergentomyia using next-generation sequencing technology.

Abstract

Next-generation sequencing (NGS) was used to investigate the genetic diversity of Leishmania tropica in the sand fly vector, targeting the internal transcribed spacer 1 (ITS1) of the genus Leishmania. Bioinformatics analyses were conducted using Galaxy, MEGA version X, DnaSP ver. 6.12.03, and PopART 1.7 software for NGS analysis, phylogenetic tree, genetic diversity, and haplotype networking, respectively. A total of 307 engorged sand flies were trapped, with an overall Leishmania infection rate of 9.4 (29/307) and 6.8% by NGS and ITS1-PCR, respectively. Two Leishmania-infectedsand fly genera were identified: Phlebotomus (10.2%, 26/254) and Sergentomyia (5.7% (3/53). The phylogenetic tree showed two clusters, cluster I included the four study sequences along with 25 GenBank-retrieved DNA sequences. Cluster II consisted of three sequences from Iran and Pakistan. The genetic diversity analysis for the 29 L. tropica sequences showed high haplotype (gene) diversity index (Hd) (0.62 ± 0.07) but low nucleotide diversity index (π) (0.04 ± 0.01). Tajima's D, a neutrality test, is more negative in cluster I (D = - 2.0) than in total population (D = - 1.83), but both are equally significant (P < 0.001), indicating that observed variation in cluster I and whole population is less frequent than expected. The median-joining haplotype network produced a total of 11 active haplotypes. In conclusion, L. tropica from sand flies in Palestine is monophyletic that assembled in one main phylogroup and one haplotype.