Differentiation and Gene Flow among European Populations of Leishmania infantum MON-1

Abstract

Background Leishmania infantum is the causative agent of visceral and cutaneous leishmaniasis in the Mediterranean region, South America, and China. MON-1 L. infantum is the predominating zymodeme in all endemic regions, both in humans and dogs, the reservoir host. In order to answer important epidemiological questions it is essential to discriminate strains of MON-1.Methodology/Principal FindingsWe have used a set of 14 microsatellite markers to analyse 141 strains of L. infantum mainly from Spain, Portugal, and Greece of which 107 strains were typed by MLEE as MON-1. The highly variable microsatellites have the potential to discriminate MON-1 strains from other L. infantum zymodemes and even within MON-1 strains. Model- and distance-based analysis detected a considerable amount of structure within European L. infantum. Two major monophyletic groups—MON-1 and non-MON-1—could be distinguished, with non-MON-1 being more polymorphic. Strains of MON-98, 77, and 108 were always part of the MON-1 group. Among MON-1, three geographically determined and genetically differentiated populations could be identified: (1) Greece; (2) Spain islands–Majorca/Ibiza; (3) mainland Portugal/Spain. All four populations showed a predominantly clonal structure; however, there are indications of occasional recombination events and gene flow even between MON-1 and non-MON-1. Sand fly vectors seem to play an important role in sustaining genetic diversity. No correlation was observed between Leishmania genotypes, host specificity, and clinical manifestation. In the case of relapse/re-infection, only re-infections by a strain with a different MLMT profile can be unequivocally identified, since not all strains have individual MLMT profiles.ConclusionIn the present study for the first time several key epidemiological questions could be addressed for the MON-1 zymodeme, because of the high discriminatory power of microsatellite markers, thus creating a basis for further epidemiological investigations.

Development of a Multilocus Microsatellite Typing Approach for Discriminating Strains of Leishmania ( Viannia ) Species

“…This needs to be verified by analyzing larger sets of samples from the different areas and by comparing the findings of distance-based analyses of MLMT data with the findings of analyses based on Bayesian statistics. The topologies of microsatellite distance trees always suffer from poor statistical support; however, in previous studies, the main clusters were always confirmed when a Bayesian model-based clustering method for inferring population structure was used (2,19,20,32). In order to evaluate the discriminatory power of our MLMT approach, we used only a limited number of Leishmania (Viannia) strains of different species and from different areas of endemicity.…”

“…Multilocus microsatellite typing (MLMT) has proven highly discriminatory in the typing of strains (5) and has been successfully used in population genetic studies of different Old World species of Leishmania (2,19,20,32). This approach could be performed directly with clinical materials without prior cultivation of the parasites.…”

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

“…LD between different genetic markers in the L. infantum complex is clear (Gouzelou et al, 2012;Kuhls et al, 2008;Mauricio et al, 2006). Some microsatellite MLGs of this species are sampled in both the Ancient and the New World .…”

The existence of only one haplotype of Leishmania major in the main and potential reservoir hosts of zoonotic cutaneous leishmaniasis using different molecular markers in a focal area in Iran

“…Microsatellite markers in Leishmania parasites are co-dominant and allelic and combine 1-7 nucleotide units into short, tandemly repeated DNA sequences 19,20 . Currently, multilocus microsatellite typing (MLMT) is being used widely in population genetic studies in different species of Leishmania parasites 21,22 . Minicircle kDNA and microsatellite ITS-rDNA are also well known as molecular markers for the detection of Leishmania infections 7,21 .…”

“…Currently, multilocus microsatellite typing (MLMT) is being used widely in population genetic studies in different species of Leishmania parasites 21,22 . Minicircle kDNA and microsatellite ITS-rDNA are also well known as molecular markers for the detection of Leishmania infections 7,21 . The Cyt b gene encodes the central catalytic subunit of an enzyme present in the respiratory chain of mitochondria and exists in almost all organisms.…”