We will continue to elucidate the subcellular physiology of intraerythrocytic P. falciparum malarial parasites using established and newly developed advanced cellular imaging techniques, and genetically well defined strains of parasites. As recent work from this laboratory and others have shown, differences in this subcellular physiology exist for chloroquine resistant (CQR) vs. sensitive (CQS) malarial parasites. These differences help define the molecular basis of drug resistance in malarial parasites and thus aid the design of new antimalarial chemotherapy. Specifically, we will: Further molecularly define intracellular pH regulation for drug resistant malarial parasites in vivo;
(Aim 1) Define additional physiologic parameters associated with malarial parasite drug resistance;
(Aim 2) Determine the relative contribution of Pfcrt, Pfmdr1, and newly described QN resistance loci to these alterations in parasite physiology (Aim 3). The proposed work is interdisciplinary and innovative. We will use novel cell culture techniques, genetically modified P. falciparum, our established single cell photometry (SCP) and laser confocal microscopy techniques, and, for the first time to our knowledge, novel spinning disk confocal microscopy (SDCM) methods. These SDCM methods allow us to acquire complete, 3 dimensional images of living intraerythrocytic parasites under constant perfusion, and at submicron resolution, within a remarkable 1 second (or less). Thus, answers to key questions that rely on (for example) rapidly quantifying sub cellular organellar volume at very high spatial resolution, are now attainable. Knowledge gained during this research will significantly expand our understanding of malarial parasite physiology and antimalarial drug resistance.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI045957-09
Application #
7570602
Study Section
Special Emphasis Panel (ZRG1-IDM-H (02))
Program Officer
Rogers, Martin J
Project Start
2000-03-01
Project End
2012-02-28
Budget Start
2009-03-01
Budget End
2012-02-28
Support Year
9
Fiscal Year
2009
Total Cost
$216,543
Indirect Cost
Name
Georgetown University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
Sherlach, Katy S; Roepe, Paul D (2014) Determination of the cytostatic and cytocidal activities of antimalarial compounds and their combination interactions. Curr Protoc Chem Biol 6:237-48
Roepe, Paul D (2014) To kill or not to kill, that is the question: cytocidal antimalarial drug resistance. Trends Parasitol 30:130-5
Gaviria, David; Paguio, Michelle F; Turnbull, Lindsey B et al. (2013) A process similar to autophagy is associated with cytocidal chloroquine resistance in Plasmodium falciparum. PLoS One 8:e79059
Gorka, Alexander P; Alumasa, John N; Sherlach, Katy S et al. (2013) Cytostatic versus cytocidal activities of chloroquine analogues and inhibition of hemozoin crystal growth. Antimicrob Agents Chemother 57:356-64
Sinai, Anthony P; Roepe, Paul D (2012) Autophagy in Apicomplexa: a life sustaining death mechanism? Trends Parasitol 28:358-64
Ghosh, Debasish; Walton, Julia L; Roepe, Paul D et al. (2012) Autophagy is a cell death mechanism in Toxoplasma gondii. Cell Microbiol 14:589-607
Roepe, Paul D (2011) PfCRT-mediated drug transport in malarial parasites. Biochemistry 50:163-71
Paguio, Michelle F; Bogle, Kelly L; Roepe, Paul D (2011) Plasmodium falciparum resistance to cytocidal versus cytostatic effects of chloroquine. Mol Biochem Parasitol 178:1-6
Alumasa, John N; Gorka, Alexander P; Casabianca, Leah B et al. (2011) The hydroxyl functionality and a rigid proximal N are required for forming a novel non-covalent quinine-heme complex. J Inorg Biochem 105:467-75
Paguio, Michelle F; Cabrera, Mynthia; Roepe, Paul D (2009) Chloroquine transport in Plasmodium falciparum. 2. Analysis of PfCRT-mediated drug transport using proteoliposomes and a fluorescent chloroquine probe. Biochemistry 48:9482-91

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