Extreme inbreeding in Leishmania braziliensis.
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.
Rougeron
Virginie
V
Génétique et Evolution des Maladies Infectieuses, IRD/CNRS/UMI (UMR 2724), Montpellier, France. rougeron.virginie@gmail.com
De Meeûs
Thierry
T
Hide
Mallorie
M
Waleckx
Etienne
E
Bermudez
Herman
H
Arevalo
Jorge
J
Llanos-Cuentas
Alejandro
A
Dujardin
Jean-Claude
JC
De Doncker
Simone
S
Le Ray
Dominique
D
Ayala
Francisco J
FJ
Bañuls
Anne-Laure
AL
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