Inference of Population Structure of Leishmania donovani Strains Isolated from Different Ethiopian Visceral Leishmaniasis Endemic Areas

Abstract

BackgroundParasites' evolution in response to parasite-targeted control strategies, such as vaccines and drugs, is known to be influenced by their population genetic structure. The aim of this study was to describe the population structure of Ethiopian strains of Leishmania donovani derived from different areas endemic for visceral leishmaniasis (VL) as a prerequisite for the design of effective control strategies against the disease.Methodology/Principal FindingsSixty-three strains of L. donovani newly isolated from VL cases in the two main Ethiopian foci, in the north Ethiopia (NE) and south Ethiopia (SE) of the country were investigated by using 14 highly polymorphic microsatellite markers. The microsatellite profiles of 60 previously analysed L. donovani strains from Sudan, Kenya and India were included for comparison. Multilocus microsatellite typing placed strains from SE and Kenya (n = 30) in one population and strains from NE and Sudan (n = 65) in another. These two East African populations corresponded to the areas of distribution of two different sand fly vectors. In NE and Sudan Phlebotomus orientalis has been implicated to transmit the parasites and in SE and Kenya P. martini. The genetic differences between parasites from NE and SE are also congruent with some phenotypic differences. Each of these populations was further divided into two subpopulations. Interestingly, in one of the subpopulations of the population NE we observed predominance of strains isolated from HIV-VL co-infected patients and of strains with putative hybrid genotypes. Furthermore, high inbreeding irreconcilable from strict clonal reproduction was found for strains from SE and Kenya indicating a mixed-mating system.Conclusions/SignificanceThis study identified a hierarchical population structure of L. donovani in East Africa. The existence of two main, genetically and geographically separated, populations could reflect different parasite-vector associations, different ecologies and varying host backgrounds and should be further investigated.

Chromosome and gene copy number variation allow major structural change between species and strains of Leishmania

“…Conversely, in L. braziliensis M2904, the high level of heterozygosity could in part be due to its triploidy (see below) and the supernumerary nature of many of its chromosomes, which, if stable, may have resulted in a redundancy of essential genes and allowed for a higher rate of neutral mutation than that of the typically diploid L. major Friedlin or L. infantum JPCM5 genomes. Recent population studies of Leishmania species have proposed inbreeding, natural selection, the Wahlund effect, or conversion on a genome-wide scale as possible causes of deficiency of heterozygous sites in strains of L. braziliensis (Rougeron et al 2009) and L. donovani (Gelanew et al 2010).…”

Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses?

“…Flores-L opez and Machado (2011) b Ni et al (2013) b,c Feil (2010) b Gatei et al (2007) b,e Taylor (2015) b,c Fraser et al (2007) b Gelanew et al (2010) d Xu (2006) b,e…”

Disseminated Cutaneous Leishmaniasis Resembling Post-Kala-Azar Dermal Leishmaniasis Caused by Leishmania donovani in Three Patients Co-Infected with Visceral Leishmaniasis and Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome in Ethiopia

“…18 The 7 strains from Ethiopian HIV/AIDS patients with cutaneous involvement and PKDL strains from other countries in eastern Africa did not belong to a particular L. donovani population, subpopulation, or cluster, but were interspersed in the tree ( Figure 4 population that comprises VL strains from north Ethiopia and Sudan. 18 The strain pair MHOM/ET/2009/DM-376sk-MHOM/ ET/2009/DM-376sp associated with concomitant disseminated CL was found in the other subpopulation (B) of NE/SD. The isolate MHOM/ET/2008/DM309/skin was different from each one of these subpopulations.…”