Complex Polymorphisms in the Plasmodium falciparum Multidrug Resistance Protein 2 Gene and Its Contribution to Antimalarial Response

Abstract

k Plasmodium falciparum has the capacity to escape the actions of essentially all antimalarial drugs. ATP-binding cassette (ABC) transporter proteins are known to cause multidrug resistance in a large range of organisms, including the Apicomplexa parasites. P. falciparum genome analysis has revealed two genes coding for the multidrug resistance protein (MRP) type of ABC transporters: Pfmrp1, previously associated with decreased parasite drug susceptibility, and the poorly studied Pfmrp2. The role of Pfmrp2 polymorphisms in modulating sensitivity to antimalarial drugs has not been established. We herein report a comprehensive account of the Pfmrp2 genetic variability in 46 isolates from Thailand. A notably high frequency of 2.8 single nucleotide polymorphisms (SNPs)/kb was identified for this gene, including some novel SNPs. Additionally, we found that Pfmrp2 harbors a significant number of microindels, some previously not reported. We also investigated the potential association of the identified Pfmrp2 polymorphisms with altered in vitro susceptibility to several antimalarials used in artemisinin-based combination therapy and with parasite clearance time. Association analysis suggested Pfmrp2 polymorphisms modulate the parasite's in vitro response to quinoline antimalarials, including chloroquine, piperaquine, and mefloquine, and association with in vivo parasite clearance. In conclusion, our study reveals that the Pfmrp2 gene is the most diverse ABC transporter known in P. falciparum with a potential role in antimalarial drug resistance. P lasmodium falciparum, the lethal pathogen of human malaria, is notorious for its capacity to develop resistance to chemotherapy. From the first observations involving quinine (1) to the latest reports on emerging artemisinin (ART) resistance (2-4), the parasite has shown a resilient ability to evade the action of essentially every launched antimalarial drug, independently of the chemical structure involved. Such an evasive capacity raises the hypothesis that the parasite is presently developing broad-range resistance phenotypes, possibly akin to the extensive drug resistance witnessed in other infectious diseases, namely, tuberculosis (5). This is a legitimate concern, particularly because of the recent reports of decreased ART sensitivity of the parasite in Southeast Asia.Conventional in vitro drug response and the parasite clearance rate (2, 3) are the main measurements to assess the resistance phenotype of the parasite, but these procedures involve demanding and time-consuming protocols. A practical alternative is the use of molecular sentinel tools, i.e., molecular markers based on genetic variations with a valuable predictive capacity in the identification of the resistance status of the analyzed infection. The development of such tools is dependent on the understanding of the drug resistance mechanisms and their associations with variants of particular genes. Such information can also provide key clues for the development of new evidence-based resistance-refractory anti...

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“…The most skewed region contains five genes (Fig 4C) including pfmrp2 ( PF3D7_1229100 ) at the center of the peak. Pfmrp2 has high genetic variability among Thai clinical isolates with single genetic variants having significant associations with in vitro response to chloroquine, mefloquine and piperaquine and in vivo parasite clearance [32].…”

“…The most skewed region on chromosome 12 overlaps with the selected region in a uncloned bulk culture of MKK2835 x NHP1337 cross F 1 progeny except that selection is against the derived allele in pfmrp2 in this case. Pfmrp2 has been associated with mefloquine and piperaquine response in vitro and parasite clearance [32] in Thai isolates and we speculate it may have a fitness cost in vitro. The role pfmrp2 plays in drug resistance is still unclear and these genetic crosses may help elucidate its function.…”

Current therapies and future possibilities for drug development against liver-stage malaria

“…In P. falciparum, resistance to CQ is conferred through the K76T mutation in the chloroquine resistance transporter gene (Pfcrt) (13). Additionally, mutations identified in the P. falciparum multidrug resistance (Pfmdr), Na + /H + exchanger (Pfnhe), and multidrug resistance-associated protein (Pfmrp1 and Pfmrp2) genes are known to contribute to quinoline resistance mechanisms (14)(15)(16). Lastly, primaquine is distinct from CQ and MQ in that it is the only clinically approved drug for treatment of relapsing malaria caused primarily by P. vivax hypnozoites.…”

Multidrug ATP‐binding cassette transporters are essential for hepatic development of Plasmodium sporozoites

“…Mutations in the gene encoding for P. falciparum MRP1 have been associated with increased resistance to antimalarials sulfadoxine-pyrimethamine, chloroquine and quinine, although its definitive role in drug responses remains controversial (Mu et al, 2003, Klokouzas et al, 2004, Dahlstrom et al, 2009b. In addition, evidence has been presented that increased MRP2 expression confers tolerance to quinolone drugs (Mok et al, 2013), and the high genetic variability in Pfmrp2 has been associated with reduced quinoline sensitivity (Veiga et al, 2014). We have previously shown that both MRP1 and MRP2 of P. falciparum are located on the plasma membrane of blood stage parasites , indicating that MRP-mediated transport may play a role in parasite growth within the erythrocyte.…”