Abstract
The objectives of this study were to investigate the molecular basis for Plasmodium falciparum resistance to chloroquine in isolates from the Brazilian Amazon and to identify polymorphisms in the pfmdr1 gene, codons 184, 1042, and 1246, the kappa and gamma regions of the cg2 gene, and the K76T mutation of the pfcrt gene, in order to calculate the distribution of polymorphism within each target gene, comparing samples from distinct geographic areas, using allele-specific polymerase chain reaction (PCR) for the pfmdr gene and PCR plus restriction fragment length polymorphism (RFLP) for the cg2 and pfcrt genes. The sample consisted of 40 human blood isolates, already collected and morphologically diagnosed as carriers of P. falciparum parasites, from four localities: Porto Velho in Rondonia State and Maraba, Itaituba, and Tailandia in Pará State. Distribution of P. falciparum in vitro chloroquine resistance in the isolates was 100% for pfmdr1, cg2 gamma region, and pfcrt, except for the polymorphism in the cg2 kappa region, which was not found.
Highlights
The objectives of this study were to investigate the molecular basis for Plasmodium falciparum resistance to chloroquine in isolates from the Brazilian Amazon and to identify polymorphisms in the pfmdr[1] gene, codons 184, 1042, and 1246, the kappa and gamma regions of the cg[2] gene, and the K76T mutation of the pfcrt gene, in order to calculate the distribution of polymorphism within each target gene, comparing samples from distinct geographic areas, using allele-specific polymerase chain reaction (PCR) for the pfmdr gene and PCR plus restriction fragment length polymorphism (RFLP) for the cg[2] and pfcrt genes
The objective of the current study was to investigate the molecular basis for P. falciparum chloroquine resistance in isolates from the Brazilian Amazon, by identifying polymorphisms in codons Asn1042Asp, Asp1246Tyr, and Tyr184Phe of the pfmdr[1] gene, polymorphisms in κ and γ in the cg[2] gene, and the K76T mutation in the pfcrt gene
The mutant allele K76T of the pfcrt gene was found in all 40 samples
Summary
The objectives of this study were to investigate the molecular basis for Plasmodium falciparum resistance to chloroquine in isolates from the Brazilian Amazon and to identify polymorphisms in the pfmdr[1] gene, codons 184, 1042, and 1246, the kappa and gamma regions of the cg[2] gene, and the K76T mutation of the pfcrt gene, in order to calculate the distribution of polymorphism within each target gene, comparing samples from distinct geographic areas, using allele-specific polymerase chain reaction (PCR) for the pfmdr gene and PCR plus restriction fragment length polymorphism (RFLP) for the cg[2] and pfcrt genes. Distribution of P. falciparum in vitro chloroquine resistance in the isolates was 100% for pfmdr[1], cg gamma region, and pfcrt, except for the polymorphism in the cg[2] kappa region, which was not found. The first references to malaria cases from chloroquine-resistant Plasmodium falciparum date to 1960 in South America and Southeast Asia, and since drug resistance has been viewed as a public health problem in various countries of the world 1. In Africa, chloroquine-resistant P. falciparum malaria has been expanding since the 1970s. Resistance to this drug is found in most the endemic countries, especially in East Africa 2,3. Clinical failure is already reaching nearly 100% in the majority of endemic areas in Brazil 1,5,6,7
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