Molecular Profiles of Multiple Antimalarial Drug Resistance Markers in Plasmodium falciparum and Plasmodium vivax in the Mandalay Region, Myanmar

Abstract

Emergence and spreading of antimalarial drug resistant malaria parasites are great hurdles to combating malaria. Although approaches to investigate antimalarial drug resistance status in Myanmar malaria parasites have been made, more expanded studies are necessary to understand the nationwide aspect of antimalarial drug resistance. In the present study, molecular epidemiological analysis for antimalarial drug resistance genes in Plasmodium falciparum and P. vivax from the Mandalay region of Myanmar was performed. Blood samples were collected from patients infected with P. falciparum and P. vivax in four townships around the Mandalay region, Myanmar in 2015. Partial regions flanking major mutations in 11 antimalarial drug resistance genes, including seven genes (pfdhfr, pfdhps, pfmdr-1, pfcrt, pfk13, pfubp-1, and pfcytb) of P. falciparum and four genes (pvdhfr, pvdhps, pvmdr-1, and pvk12) of P. vivax were amplified, sequenced, and overall mutation patterns in these genes were analyzed. Substantial levels of mutations conferring antimalarial drug resistance were detected in both P. falciparum and P. vivax isolated in Mandalay region of Myanmar. Mutations associated with sulfadoxine-pyrimethamine resistance were found in pfdhfr, pfdhps, pvdhfr, and pvdhps of Myanmar P. falciparum and P. vivax with very high frequencies up to 90%. High or moderate levels of mutations were detected in genes such as pfmdr-1, pfcrt, and pvmdr-1 associated with chloroquine resistance. Meanwhile, low frequency mutations or none were found in pfk13, pfubp-1, pfcytb, and pvk12 of the parasites. Overall molecular profiles for antimalarial drug resistance genes in malaria parasites in the Mandalay region suggest that parasite populations in the region have substantial levels of mutations conferring antimalarial drug resistance. Continuous monitoring of mutations linked with antimalarial drug resistance is necessary to provide useful information for policymakers to plan for proper antimalarial drug regimens to control and eliminate malaria in the country.

Keywords: Myanmar; Plasmodium falciparum; Plasmodium vivax; drug resistance genes; malaria.

Figure 1

Blood samples collection site map. Blood samples of malaria patients were collected in the four townships, Mandalay region, Myanmar, in 2015.

Figure 2

Frequencies and distributions of dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) in Myanmar P. falciparum isolates. (A) Overall prevalence of mutations identified in pfdhfr and pfdhps. (B) Overall frequency of haplotypes of pfdhfr and pfdhps. The amino acid codons in haplotypes corresponded to the amino acids specified in (A). (C) Proportion of haplotypes of pfdhfr and pfdhps in each township.

Figure 3

Frequencies and distributions of multidrug resistance 1 (pfmdr-1) and chloroquine resistance transporter (pfcrt) in Myanmar P. falciparum isolates. (A) Overall prevalence of mutations identified in pfmdr-1 and pfcrt. (B) Overall frequency of haplotypes of pfmdr-1 and pfcrt. The amino acid codons in haplotypes corresponded to the amino acids specified in (A). (C) Proportion of haplotypes of pfmdr-1 and pfcrt in each township.

Figure 4

Frequencies and distributions of Kelch 13 (pfk13), ubiquitin specific protease 1 (pfubp-1) and cytochrome b (pfcytb) in Myanmar P. falciparum isolates. (A) Overall prevalence of mutations identified in pfk13, pfubp-1, and pfcytb. (B) Overall frequency of haplotypes of pfk13, pfubp-1, and pfcytb. The amino acid codons in haplotypes corresponded to the amino acids specified in (A). (C) Proportion of haplotypes of pfk13, pfubp-1, and pfcytb in each township.

Figure 5

Combinational analysis of the mutations in five genes associated with antimalarial drug resistance in P. falciparum. Mutations in each gene highlighted with different colors and wild type residues shown as closed circles. Grey boxes represented samples failed to amplify.

Figure 6

Frequencies and distributions of dihydrofolate reductase (pvdhfr) and dihydropteroate synthase (pvdhps) in Myanmar P. vivax isolates. (A) Overall prevalence of mutations identified in pvdhfr and pvdhps. (B) Overall frequency of haplotypes of pvdhfr and pvdhps. The amino acid codons in haplotypes corresponded to the amino acids specified in (A). (C) Proportion of haplotypes of pvdhfr and pvdhps in each township.

Figure 7

Frequencies and distributions of multidrug resistance 1 (pvmdr-1) and kelch 12 (pvk12) in Myanmar P. vivax isolates. (A) Overall prevalence of mutations identified in pvmdr-1 and pvk12. (B) Overall frequency of haplotypes of pvmdr-1 and pvk12. The amino acid codons in haplotypes corresponded to the amino acids specified in (A). (C) Proportion of haplotypes of pvmdr-1 and pvk12 in each township.

Figure 8

Combinational analysis of the mutations in four genes associated with antimalarial drug resistance in P. vivax. Mutations in each gene highlighted with different colors and wild type residues shown as closed circles. Grey boxes represented samples failed to amplify.