Expanded genome-wide comparisons give novel insights into population structure and genetic heterogeneity of Leishmania tropica complex

PLoS Negl Trop Dis. 2020 Sep 18;14(9):e0008684. doi: 10.1371/journal.pntd.0008684. eCollection 2020 Sep.

Abstract

Leishmania tropica is one of the main causative agents of cutaneous leishmaniasis (CL). Population structures of L. tropica appear to be genetically highly diverse. However, the relationship between L. tropica strains genomic diversity, protein coding gene evolution and biogeography are still poorly understood. In this study, we sequenced the genomes of three new clinical L. tropica isolates, two derived from a recent outbreak of CL in camps hosting Syrian refugees in Lebanon and one historical isolate from Azerbaijan to further refine comparative genome analyses. In silico multilocus microsatellite typing (MLMT) was performed to integrate the current diversity of genome sequence data in the wider available MLMT genetic population framework. Single nucleotide polymorphism (SNPs), gene copy number variations (CNVs) and chromosome ploidy were investigated across the available 18 L. tropica genomes with a main focus on protein coding genes. MLMT divided the strains in three populations that broadly correlated with their geographical distribution but not populations defined by SNPs. Unique SNPs profiles divided the 18 strains into five populations based on principal component analysis. Gene ontology enrichment analysis of the protein coding genes with population specific SNPs profiles revealed various biological processes, including iron acquisition, sterols synthesis and drug resistance. This study further highlights the complex links between L. tropica important genomic heterogeneity and the parasite broad geographic distribution. Unique sequence features in protein coding genes identified in distinct populations reveal potential novel markers that could be exploited for the development of more accurate typing schemes to further improve our knowledge of the evolution and epidemiology of the parasite as well as highlighting protein variants of potential functional importance underlying L. tropica specific biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Azerbaijan
  • DNA Copy Number Variations
  • DNA, Protozoan / genetics
  • Gene Dosage
  • Genetic Variation*
  • Genome, Protozoan*
  • Geographic Mapping
  • Humans
  • Lebanon
  • Leishmania tropica / genetics*
  • Leishmaniasis, Cutaneous / parasitology
  • Leishmaniasis, Cutaneous / pathology
  • Microsatellite Repeats
  • Phylogeny
  • Polymorphism, Single Nucleotide
  • Refugees
  • Syria

Substances

  • DNA, Protozoan

Grants and funding

This work was financed by the School of Arts and Sciences at the Lebanese American University, Office of Graduate Studies and Research (Grant number GSR-R0063) and Newcastle University that partially supported TS with an Overseas Research Scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.