Are pvcrt-o and pvmdr1 Gene Mutations Associated with Plasmodium vivax Chloroquine-Resistant Parasites?

(1) Background: Malaria remains a significant global public health issue. Since parasites quickly became resistant to most of the available antimalarial drugs, treatment effectiveness must be constantly monitored. In Brazil, up to 10% of cases of vivax malaria resistant to chloroquine (CQ) have been registered. Unlike P. falciparum , there are no definitive molecular markers for the chemoresistance of P. vivax to CQ. This work aimed to investigate whether polymorphisms in the pvcrt-o and pvmdr1 genes could be used as markers for assessing its resistance to CQ. (2) Methods: A total of 130 samples from P. vivax malaria cases with no clinical and/or parasitological evidence of CQ resistance were studied through polymerase chain reaction for gene amplification followed by target DNA sequencing. (3) Results: In the pvcrt-o exons, the K10 insert was present in 14% of the isolates. Regarding pvmdr1 , T958 M and F1076 L haplotypes showed frequencies of 95% and 3%, respectively, while the SNP Y976 F was not detected. (4) Conclusions: Since K10- pvcrt-o and F1076 L /T958 M - pvmdr1 polymorphisms were detected in samples from patients who responded well to CQ treatment, it can be concluded that mutations in these genes do not seem to have a potential for association with the phenotype of CQ resistance.