Variations in the sequence and expression of the Plasmodium falciparum chloroquine resistance transporter (Pfcrt) and their relationship to chloroquine resistance in vitro.

Chloroquine has been widely used for malaria treatment and prophylaxis for several decades, but its usefulness has now declined with the emergence of chloroquine resistance. Recent studies showed that the K76T mutation in the PfCRT protein, initially associated to chloroquine-resistant parasites, is sometimes also present in susceptible parasites, suggesting that other factors control the expression of the resistance phenotype. Here, we sought new mutations in the Pfcrt gene and used real-time PCR to investigate variations in the expression level of this gene with respect to the in vitro response to chloroquine.