title: Extreme inbreeding in Leishmania braziliensis.
abstract: Leishmania species of the subgenus Viannia and especially Leishmania braziliensis are responsible for a large proportion of New World leishmaniasis cases. The reproductive mode of Leishmania species has often been assumed to be predominantly clonal, but remains unsettled. We have investigated the genetic polymorphism at 12 microsatellite loci on 124 human strains of Leishmania braziliensis from 2 countries, Peru and Bolivia. There is substantial genetic diversity, with an average of 12.4 +/- 4.4 alleles per locus. There is linkage disequilibrium at a genome-wide scale, as well as a substantial heterozygote deficit (more than 50% the expected value from Hardy-Weinberg equilibrium), which indicates high levels of inbreeding. These observations are inconsistent with a strictly clonal model of reproduction, which implies excess heterozygosity. Moreover, there is large genetic heterogeneity between populations within countries (Wahlund effect), which evinces a strong population structure at a microgeographic scale. Our findings are compatible with the existence of population foci at a microgeographic scale, where clonality alternates with sexuality of an endogamic nature, with possible occasional recombination events between individuals of different genotypes. These findings provide key clues on the ecology and transmission patterns of Leishmania parasites.
authors.affiliation: Génétique et Evolution des Maladies Infectieuses, IRD/CNRS/UMI (UMR 2724), Montpellier, France. rougeron.virginie@gmail.com
authors.forename: Virginie
authors.initials: V
authors.lastname: Rougeron
authors.forename: Thierry
authors.initials: T
authors.lastname: De Meeûs
authors.forename: Mallorie
authors.initials: M
authors.lastname: Hide
authors.forename: Etienne
authors.initials: E
authors.lastname: Waleckx
authors.forename: Herman
authors.initials: H
authors.lastname: Bermudez
authors.forename: Jorge
authors.initials: J
authors.lastname: Arevalo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Llanos-Cuentas
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dujardin
authors.forename: Simone
authors.initials: S
authors.lastname: De Doncker
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Ray
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Ayala
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Bañuls
mesh_terms: D000818:Animals; D001838:Bolivia; D006579:Heterozygote; D006801:Humans; D007892:Leishmania braziliensis / Q000235:genetics*; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats / Q000235:genetics; D010568:Peru; D011110:Polymorphism, Genetic; D012098:Reproduction / Q000235:genetics