RESUMO
BACKGROUND/OBJECTIVES: Parasites of the subgenus Leishmania (Viannia) cause varying clinical symptoms ranging from cutaneous leishmaniases (CL) with single or few lesions, disseminated CL (DL) with multiple lesions to disfiguring forms of mucocutaneous leishmaniasis (MCL). In this population genetics study, 37 strains of L. (V.) guyanensis, 63 of L. (V.) braziliensis, four of L. (V.) shawi, six of L. (V.) lainsoni, seven of L. (V.) naiffi, one each of L. (V.) utingensis and L. (V.) lindenbergi, and one L. (V.) lainsoni/L. naiffi hybrid from different endemic foci in Brazil were examined for variation at 15 hyper-variable microsatellite markers. METHODOLOGY/PRINCIPAL FINDINGS: The multilocus microsatellite profiles obtained for the 120 strains were analysed using both model- and distance-based methods. Significant genetic diversity was observed for all L. (Viannia) strains studied. The two cluster analysis approaches identified two principal genetic groups or populations, one consisting of strains of L. (V.) guyanensis from the Amazon region and the other of strains of L. (V.) braziliensis isolated along the Atlantic coast of Brazil. A third group comprised a heterogeneous assembly of species, including other strains of L. braziliensis isolated from the north of Brazil, which were extremely polymorphic. The latter strains seemed to be more closely related to those of L. (V.) shawi, L. (V.) naiffi, and L. (V.) lainsoni, also isolated in northern Brazilian foci. The MLMT approach identified an epidemic clone consisting of 13 strains of L. braziliensis from Minas Gerais, but evidence for recombination was obtained for the populations of L. (V.) braziliensis from the Atlantic coast and for L. (V.) guyanensis. CONCLUSIONS/SIGNIFICANCE: Different levels of recombination versus clonality seem to occur within the subgenus L. (Viannia). Though clearly departing from panmixia, sporadic, but long-term sustained recombination might explain the tremendous genetic diversity and limited population structure found for such L. (Viannia) strains.
Assuntos
Variação Genética , Leishmania/classificação , Leishmania/genética , Recombinação Genética , Brasil , Análise por Conglomerados , DNA de Protozoário/genética , Genótipo , Técnicas de Genotipagem , Humanos , Leishmania/isolamento & purificação , Leishmaniose/parasitologia , Repetições de MicrossatélitesAssuntos
Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/etiologia , Biópsia , Criança , Doenças Endêmicas , Granuloma/diagnóstico , Humanos , Leishmania donovani/metabolismo , Leishmaniose Cutânea/tratamento farmacológico , Masculino , Paromomicina/uso terapêutico , Pele/patologia , Viagem , Resultado do TratamentoRESUMO
In order to understand the epidemiological dynamics of antimonial (Sb(V)) resistance in zoonotic tegumentary leishmaniasis and its link with treatment outcome, we analyzed the population structure of 24 Peruvian Leishmania braziliensis clinical isolates with known in vitro antimony susceptibility and clinical phenotype by multilocus microsatellite typing (14 microsatellite loci). The genetic variability in the Peruvian isolates was high and the multilocus genotypes were strongly differentiated from each other. No correlation was found between the genotypes and in vitro drug susceptibility or clinical treatment outcome. The finding of a polyphyletic pattern among the Sb(V)-resistant L. braziliensis might be explained by (i) independent events of drug resistance emergence, (ii) sexual recombination and/or (iii) other phenomena mimicking recombination signals. Interestingly, the polyphyletic pattern observed here is very similar to the one we observed in the anthroponotic Leishmania donovani (Laurent et al., 2007), hereby questioning the role of transmission and/or chemotherapeutic drug pressure in the observed population structure.
Assuntos
Antimônio/farmacologia , Antiprotozoários/farmacologia , Resistência a Medicamentos/genética , Leishmania braziliensis/classificação , Leishmania braziliensis/efeitos dos fármacos , Leishmania braziliensis/genética , Animais , Antimônio/uso terapêutico , Antiprotozoários/uso terapêutico , Variação Genética , Genótipo , Humanos , Leishmania braziliensis/patogenicidade , Leishmaniose Cutânea/tratamento farmacológico , Repetições de Microssatélites , Testes de Sensibilidade Parasitária , Peru , Resultado do TratamentoRESUMO
The evolutionary history of Leishmania chagasi, the aetiological agent of visceral leishmaniasis in South America has been widely debated. This study addresses the problem of the origin of L. chagasi, its timing and demography with fast evolving genetic markers, a suite of Bayesian clustering algorithms and coalescent modelling. Here, using 14 microsatellite markers, 450 strains from the Leishmania donovani complex, we show that the vast majority of the Central and South American L. chagasi were nested within the Portuguese Leishmania infantum clade. Moreover, L. chagasi allelic richness was half that of their Old World counterparts. The bottleneck signature was estimated to be about 500 years old and the settlement of L. chagasi in the New World, probably via infected dogs, was accompanied by a thousand-fold population decrease. Visceral leishmaniasis, lethal if untreated, is therefore one more disease that the Conquistadores brought to the New World.