Evaluation of Plasmodium falciparum K13 gene polymorphism and susceptibility to dihydroartemisinin in an endemic area

Abstract

Introduction: Plasmodium falciparum has developed resistance to artemisinin drugs in Southeast Asia, and its reduced sensitivity has been reported in other regions. This study aims to determine parasite susceptibility to the bioactive form of artemisinin derivatives- dihydroartemisinin (DHA)-, and to detect the K13 polymorphism in isolates from an endemic area of Nigeria.
 Methods: Ex-vivo response in 55 parasites isolates obtained from malaria-positive patients were exposed to pulse DHA concentration and cultured for 66 hours ex-vivo. Parasite ring stage survival (RSAex-vivo) relative to unexposed matched control was determined by microscopy, and parasite growth was compared using Mann-Whitney U-test at a significance level of P<0.05. The Kelch propeller gene was amplified using specific primers, then sequenced and analyzed for single nucleotide polymorphisms (SNPs), which were compared to reference PF3D7_1343700.
 Results: Overall, 151 of 375 (40.2%) individuals were positive during the study period. In 55 selected isolates, there was increased growth in unexposed wells but growth was inhibited in DHA-exposed wells, with growth rate between 14.9 – 96.7%. The mean RSAex-vivo value was 0.18 ± 0.09%, 95% CI (0.15-0.20). There was no significant mutation of the K13 gene in the parasite isolates evaluated.
 Conclusions: Plasmodium falciparum isolates from this endemic area show high sensitivity to dihydroartemisinin ex-vivo, with no mutations conferring artemisinin resistance. Continuous monitoring of parasite susceptibility to artemisinin combination drugs should be intensified to reduce chances of artemisinin resistance in endemic areas.

Molecular profiling of the artemisinin resistance Kelch 13 gene in Plasmodium falciparum from Nigeria

“…None of them was among the ten SNPs (F446I, N458Y, M476I, Y493H, R539T, I543T, P553L, R561H, P574L and C580Y) which have been validated to be associated with artemisinin resistance in Southeast Asia, South America and Rwanda [ 2 , 6 – 9 ]. The absence of the validated mutations in our study is in line with many recent studies carried out in Africa [ 32 – 40 ] and in Nigeria [ 20 , 27 , 29 , 34 , 41 , 42 ].…”

Polymorphism Analysis of pfmdr1 and pfcrt from Plasmodium falciparum Isolates in Northwestern Nigeria Revealed the Major Markers Associated with Antimalarial Resistance

“…Since, a handful of studies have documented treatment failure in patients treated with artemether and/or ACT partner drugs like amodiaquine, e.g., [ 13 , 15 , 16 , 17 ]. Studies carried out to detect mutations in the kelch13 gene to date have found none of the major mutations associated with delayed parasite clearance in isolates from Nigeria [ 18 , 19 , 20 , 21 , 22 ]. However, except for [ 22 ] these recent studies were all carried out in southern Nigeria, with little known of kelch13 resistance markers in northern Nigeria.…”

Grasp of dihydroartemisinin resistance in Indonesia: Focused on genetic polymorphisms and new antimalarial

“…On the other hand, studies in the absence of Kelch13 -resistant genotypes in P. falciparum isolates from malaria patients in Cameroon were associated with total parasite clearance, high reduction of parasite loads, and resolved symptoms [ 22 ]. Other studies concerning polymorphism have reported that genetic variations in the Pfmdr1 and Pfcrt genes are associated with reduced susceptibility to aminoquinoline antimalarial drugs, especially when compared to parasites that have not been exposed [ 23 ]. In addition, a study reported the prevalence of polymorphisms in the Pfkelch13, Pfcrt , and Pfmdr1 genes among Chinese migrant workers who returned to Guangxi Province from Africa.…”