O EFEITO DA PRESSÃO SELETIVA COM PRAZIQUANTEL NA DIVERSIDADE GENÉTICA DA CEPA LE DE Schistosoma mansoni.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Schistosomiasis is one of the parasitic diseases that make a considerable impact upon public health worldwide. In Brazil, it is caused by the digenetic trematode Schistosoma mansoni. The most important schistosomiasis control measure is a large-scale specific chemotherapy. Currently, the drug chosen for schistosomiasis treatment is praziquantel (PZQ). Although PZQ is efficient and safe, its use on a large-scale in repetitive treatments, in endemic areas, may lead to the selection of resistant strains. Resistant or low susceptible to PZQ isolates have already been found in Nature, and can also be selected in laboratory. The impact of selecting strains with a resistance-phenotype has not been investigated yet. The present work was aimed at selecting a S. mansoni resistant strain to PZQ, analyzing its genetic profile in comparison with the origin strain by using polymorphic markers, microsatellite type. In order to induce resistance to PZQ, the LE S. mansoni strain was used. Infected mice were treated with increasing PZQ doses until the curative dose was reached throughout seven generations. DNA from worms obtained at each generation was analyzed by using six microsatellite loci. Parasitological and genetic data were compared with those from the same strain with no resistance induction. After six parasite generations submitted to PZQ treatment, it was possible to obtain a S. mansoni strain with a decreased susceptibility to PZQ. Female worms showed a higher susceptibility to PZQ when compared with males in the selected population. The selective pressure with PZQ led to a decreased genetic variability of S. mansoni. There was no significant difference concerning genetic variability between males and females. Obtaining a resistant strain to PZQ is important for a better understanding of the parasite resistance mechanisms which would be also useful for further comparisons of sensitivity levels among field isolates.

ASSUNTO(S)

schistosoma mansoni resistência biologia molecular drogas diversidade biológica

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