Furthermore, all samples were assayed for 5 microsatellite loci that span [approximately equal to] 11 kb on chromosome 4 around Pfdhfr, 9 loci that span 17 kb on chromosome 8 around Pfdhps, 4 loci that span 11 kb on chromosome 7 around Pfcrt
, and 6 loci that span 8 kb on chromosome 5 around Pfmdr1.
Mutations conferring drug resistance in malaria parasite drug transporters Pgh1 and PfCRT
do not affect steady-state vacuolar [Ca.
Now, the Australian team has proved that PfCRT
"provides an exit route for chloroquine," which does not reach the concentration required to kill the parasite.
Although evidence for the association of Pfmdr1 with chloroquine resistance has not been as convincing as for Pfcrt
, a recent parasite transfection experiment showed that polymorphisms in the Pfmdr1 gene modulate susceptibility to chloroquine (as well as to mefloquine and the structurally related compounds quinine and halofantrine) (22).
The aim of this study was to compare the prevalence rate of the Pfcrt
T76 mutation in P.
After a short training course, they are able to collect blood samples from finger pricks and spot them onto filter paper strips that are sent to regional sites that detect PfCRT
76T, the key mutation causing chloroquine resistance.
We aimed to search for chloroquine-resistant cases either clinically or by detecting pfcrt
haplotypes in P.
CVIET haplotype is common in Southeast Asia and sub-Saharan Africa and was found in the 2006-2007 study in Haiti (10).
The profile associated with quinine resistance for chloroquine resistance and pfcrt
genotypes could be different in the 3 malaria-endemic continents.
Genotyping each of the 117 parasite isolates at 16 drug resistance-related codons in the pfcrt
, pfmdrl, pfdhfr, and pfdhps genes showed 41 haplotypes (Figure 1).
Genotyping results for 2 Plasmodium falciparum isolates, France, 2009 * Secondary case Index case Locus Type Allele Type Allele Microsatellites ([dagger]) 7A11 NA 119 bp NA 119 bp C4M79 NA 203 bp NA 203 bp Pf2802 NA 139 bp NA 139 bp Pf2689 NA 87 bp NA 87 bp Antigen genes ([double dagger]) msp-1 Ro33 149 bp Ro33 149 bp msp-2 FC27 413 bp FC27 413 bp Drug resistance genes ([section]) pfcrt
codon 76 Mutated ACA Mutated ACA pfdhfr Codon 16 Wild-type GCA Wild-type GCA Codon 51 Mutated ATT Mutated ATT Codon 59 Mutated CGT Mutated CGT Codon 108 Mutated AAC Mutated AAC Codon 164 Wild-type ATA Wild-type ATA * NA, not applicable; msp, merozoite surface protein; pfcrt
gene was amplified by seminested PCR, and the codon 76 mutation was genotyped by using a simple PCR-restriction fragment digest assay and fluorescent detection of products on an ABI 3130XL capillary sequencer, as described (16).