The worldwide adoption of artemisinin-based combination therapies (ACTs) has been instrumental in halving the global burden of Plasmodium falciparum (Pf) malaria since the early 2000s. Malaria?s impact nonetheless remains vast, with over 400,000 yearly deaths in Africa alone. Now, Pf resistance to ACTs threatens to overwhelm malaria control efforts. Treatment failure rates with the ACT dihydroartemisinin+piperaquine (PPQ) currently exceed 50% in Cambodia, and resistance to other ACTs has been observed elsewhere in Asia. The emergence and spread of ACT resistance in Africa would be calamitous. Studies have identified core roles for the Pf chloroquine resistance transporter PfCRT and the multidrug resistance transporter PfMDR1 in modulating Pf susceptibility to the ACT partner drugs PPQ, amodiaquine (ADQ), pyronaridine (PND), lumefantrine (LMF) and mefloquine (MFQ). These studies include our recent gene editing-based finding that novel PfCRT mutations present in Cambodia can confer PPQ resistance. By analyzing a dataset of >2,500 Pf genomes sampled across Asia and Africa, we now find a plethora of new sequence variants of both genes.
In Aim 1, we will apply gene editing techniques coupled with comprehensive drug susceptibility profiling to test the hypothesis that these novel PfCRT mutations have been selected to mediate ACT partner drug resistance. In Asia, we predict that these variants primarily affect susceptibility to PPQ, LMF, or MFQ. In Africa, we observe a predominance of previously uncharacterized haplotypes, and will characterize whether these variants mediate reduced susceptibility to partner drugs and/or minimize fitness costs.
In Aim 2, we will test the hypothesis that current ACTs are selecting for novel mutations in PfMDR1 throughout Asia and Africa. Based on our recent discovery of a role for PfMDR1 as a mediator of gametocyte resistance to antimalarials, we will also assess whether mutant PfMDR1 isoforms can enhance the transmission of drug-resistant Pf parasites.
In Aim 3, we propose to identify antimalarial combinations that exert opposing selective pressures on PfCRT and PfMDR1 and thus preclude the acquisition of multidrug resistance. Using selection methods with mutant pfcrt and pfmdr1 lines, our studies will experimentally address the premise of two ongoing triple ACT clinical trials in Cambodia, which are testing the dual partner drug combinations LMF+ADQ and PPQ+MFQ as approaches to effectively treat drug-resistant malaria and prevent its further evolution and spread.
In Aim 4, we will use cell- based assays to test the hypothesis that hemoglobin endocytosis and subsequent processing in the Pf digestive vacuole are key aspects of the modes of action of most ACT drugs, whose potency can be impacted by mutant isoforms of PfMDR1 or PfCRT. This proposal, which aligns with the NIAID priority of supporting research on antimicrobial drug resistance, will transform our understanding of ACT partner drug resistance and modes of action, provide new biomarkers, and identify strategies to effectively treat drug-resistant Pf malaria.

Public Health Relevance

The effective treatment of malaria is being increasingly threatened by the emergence of Plasmodium falciparum parasite strains that are resistant to artemisinin-based combination therapies. Here, we propose to test the hypothesis that multiple new mutations in the parasite transporters PfCRT and PfMDR1 are driving the emergence of resistance to combination therapy partner drugs, and extend this to examine whether PfMDR1 mutations enhance transmission, identify partner drug combinations for which resistance mechanisms are mutually exclusive, and investigate the role of hemoglobin import and processing in partner drug modes of action. Results from this project will advance our understanding of P. falciparum drug action and resistance, and identify biomarkers and combinations to effectively monitor and treat drug-resistant malaria.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI050234-17
Application #
9644485
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
O'Neil, Michael T
Project Start
2001-08-01
Project End
2023-01-31
Budget Start
2019-02-01
Budget End
2020-01-31
Support Year
17
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Cowell, Annie N; Istvan, Eva S; Lukens, Amanda K et al. (2018) Mapping the malaria parasite druggable genome by using in vitro evolution and chemogenomics. Science 359:191-199
Ross, Leila S; Dhingra, Satish K; Mok, Sachel et al. (2018) Emerging Southeast Asian PfCRT mutations confer Plasmodium falciparum resistance to the first-line antimalarial piperaquine. Nat Commun 9:3314
Schuh, Anna Katharina; Rahbari, Mahsa; Heimsch, Kim C et al. (2018) Stable Integration and Comparison of hGrx1-roGFP2 and sfroGFP2 Redox Probes in the Malaria Parasite Plasmodium falciparum. ACS Infect Dis 4:1601-1612
Lee, Andrew H; Dhingra, Satish K; Lewis, Ian A et al. (2018) Evidence for Regulation of Hemoglobin Metabolism and Intracellular Ionic Flux by the Plasmodium falciparum Chloroquine Resistance Transporter. Sci Rep 8:13578
Agrawal, Sonia; Moser, Kara A; Morton, Lindsay et al. (2017) Association of a Novel Mutation in the Plasmodium falciparum Chloroquine Resistance Transporter With Decreased Piperaquine Sensitivity. J Infect Dis 216:468-476
Vanaerschot, Manu; Lucantoni, Leonardo; Li, Tao et al. (2017) Hexahydroquinolines are antimalarial candidates with potent blood-stage and transmission-blocking activity. Nat Microbiol 2:1403-1414
Rahbari, Mahsa; Rahlfs, Stefan; Przyborski, Jude M et al. (2017) Hydrogen peroxide dynamics in subcellular compartments of malaria parasites using genetically encoded redox probes. Sci Rep 7:10449
Blasco, Benjamin; Leroy, Didier; Fidock, David A (2017) Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic. Nat Med 23:917-928
Dhingra, Satish K; Redhi, Devasha; Combrinck, Jill M et al. (2017) A Variant PfCRT Isoform Can Contribute to Plasmodium falciparum Resistance to the First-Line Partner Drug Piperaquine. MBio 8:
Gabryszewski, Stanislaw J; Dhingra, Satish K; Combrinck, Jill M et al. (2016) Evolution of Fitness Cost-Neutral Mutant PfCRT Conferring P. falciparum 4-Aminoquinoline Drug Resistance Is Accompanied by Altered Parasite Metabolism and Digestive Vacuole Physiology. PLoS Pathog 12:e1005976

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