Abstracts 501-750
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150 salivary glands was greatly reduced by ron2 silencing, despite sporogony, and accompanying upregulation of PfRad51, PfRad54, PfRPA1L and sporozoite release into hemocoel and their motility were normal. These PfRPA1S at the level of transcript and protein. This study provides new results showed that RON2 is required for salivary gland invasion. This is the insights into the role of putative Rad51-interacting proteins involved in first genetical approach to show that RON2 has an important role in target homologous recombination and emphasizes physiological role of DNA cell invasion. damage repair during the growth of parasites. We are now characterizing the recombiantion macromolecular complex which is likely to be important 499 in DNA damage and repair and validating molecular interactions between PfRad51 and its putative interacting partners. Besides understanding IDENTIFICATION AND CHARACTERIZATION OF A molecular machinery involved in DNA repair and recombination, we wish PLASMODIUM FALCIPARUM ORTHOLOGUE OF THE YEAST to extend our studies to understand the biochemical and genetic basis of UBIQUINONE-BINDING PROTEIN, COQ10P gene rearrangements at the var gene locus associated with phenomenon like antigenic variation. Bethany J. Jenkins, Joanne M. Morrisey, Thomas M. Daly, Michael W. Mather, Akhil B. Vaidya, Lawrence W. Bergman 501 Drexel University College of Medicine, Philadelphia, PA, United States Coenzyme Q (CoQ, ubiquinone) is a central electron carrier in A SINGLE NUCLEOTIDE POLYMORPHISM IN THE PROMOTER mitochondrial respiration. CoQ is synthesized through multiple steps OF STROMAL CELL-DERIVED FACTOR (SDF)-1α (C-1002T) IS involving a number of different proteins. The prevailing view that the ASSOCIATED WITH PROTECTION AGAINST PLASMODIUM CoQ used in respiration exists as a free pool that diffuses throughout FALCIPARUM INFECTION IN KENYAN CHILDREN the mitochondrial inner membrane bilayer has recently been challenged. 1 1 1 2 In the yeast Saccharomyces cerevisiae, deletion of the gene encoding Grace Okello , Zachary Karim , Prakasha Kempaiah , Eric Otieno , 3 4 4 1 Coq10p results in respiration deficiency without altering total size of the James Hittner , John Vulule , John Ong’echa , Douglas Perkins , 4 available CoQ pool, suggesting that the Coq10p is critical for the delivery Tom Were of CoQ to the site(s) of respiration. The precise mechanism by which 1Center for Global Health - University of New Mexico, Albuquerque, this is achieved remains unknown at present. Because mitochondrial NM, United States, 2Laboratories of Parasitic and Viral Diseases, Centre respiration is a validated target for antimalarial drugs such as atovaquone, for Global Health Research, Kisumu, Kenya, 3Department of Psychology, we are interested in examining its regulation in malaria parasites. We have College of Charleston, Charleston, SC, United States, 4Centre for Global identified an orthologue of Coq10p, PfCoq10, in P. falciparum, the most Health Research, Kenya Medical Research Institute, Kisumu, Kenya virulent species of malaria parasite, and demonstrated that a GFP-tagged Stromal cell-derived factor (SDF)-1α (CXCL12) is a pleiotropic chemokine version of PfCoq10 localized to the parasite mitochondrion. Expression of with diverse functions including induction of anti-pathogen immunity PfCoq10 in the S. cerevisiae coq10 deletion strain restored the capability and inhibition of erythropoiesis. In murine malaria, increased expression of the yeast to grow on respiratory substrates, suggesting a remarkable of SDF-1α promotes control of parasitemia. Although several studies functional conservation of this protein over a vast evolutionary distance, indicate that SDF1A genetic variation regulates outcomes in the context and despite a relatively low level of amino acid sequence identity. We are of HIV-1 infection, hematopoiesis, and cancer, the role of genetic currently assessing effects of PfCoq10 overexpression on the atovaquone variability in SDF1A in Plasmodium falciparum infections has not been sensitivity of P. falciparum. We are also examining the possibility of altered explored. The effect of SDF1A (C-1002T, rs2839686) variation was response to atovaquone in yeast mitochondria expressing the parasite therefore, investigated in Kenyan children (2.0-38.0mos., n=873) residing Coq10. These studies may provide insights into respiration regulation in in a holoendemic P. falciparum transmission region of western Kenya. general, as well as in malaria parasites. Children were stratified into aparasitemic (n=212) and parasitemic (n=661) groups with parasitemic children being further categorized into SMA 500 (hemoglobin, Hb<5.0g/dL; n=236) vs. non-SMA (Hb≥5.0g/dL; n=425), high-density parasitemia (HDP; ≥10,000 parasites/µL; n=477) vs. low- ROLE OF PFRAD54 AND REPLICATION PROTEIN A IN RAD51- density parasitemia (LDP; <10,000 parasites/µL; n=184), and reticulocyte MEDIATED DNA STRAND EXCHANGE AND REPAIR OF DNA production index (RPI<2.0) vs. (RPI≥2.0). Multivariate logistic regression DAMAGE INDUCED BY MMS IN PLASMODIUM FALCIPARUM modeling controlling for age, gender, bacteremia, glucose-6-phosphate dehydrogenase, alpha-thalasemia, and sickle cell and HIV-1 status did not Anusha M. Gopalakrishnan, Nirbhay Kumar show any significant associations between carriage of C-1002T genotypes Tulane University School of Public Health, New Orleans, LA, United States and SMA, RPI<2.0, and HDP. However, carriage of the CC genotype was Exploiting the recombination machinery and its molecular characterization associated with protection against the acquisition of P. falciparum infection in the malaria parasite would provide mechanistic understanding of compared to the TT genotype (Odds ratio, OR, 0.311; 95% CI, 0.115- recombinational rearrangements leading to immune evasion via antigenic 0.842; P=0.022). These results demonstrate that although variation at switching, a major impediment in developing an effective vaccine against 1002 in the SDF1A promoter appears to protect against acquisition of P. these protozoan parasites. Bacterial RecA protein and its eukaryotic falciparum infection, this variant may not affect malaria disease outcomes homologue Rad51 play a central role in homologous DNA strand once an individual becomes infected. exchange reaction during recombination and DNA repair. Previously, our lab has shown that PfRad51, the Plasmodium falciparum homologue of 502 Rad51, exhibited ATPase activity and promoted DNA strand exchange in vitro, as reported previously. Here, we evaluated the catalytic functions GENOMIC DIVERSITY AND evolutionary history OF of PfRad51 in the presence of putative interacting partners, especially PLASMODIUM vivax P. falciparum homologues of Rad54 and Replication protein-A (RPA). Ernest R. Chan1, Didier Menard2, Odile Mercereau-Puijalon3, PfRad54 accelerated PfRad51 mediated pairing between ssDNA and its Peter Zimmerman4, David Serre1 homologous linear dsDNA in the presence of 0.5mM CaCl2. We also present evidence that recombinant PfRPA1L protein serves the function 1Cleveland Clinic Foundation, Cleveland, OH, United States, 2Institut of bacterial homologue SSB in initiating homologous pairing and strand Pasteur du Cambodge, Phnom Penh, Cambodia, 3Institut Pasteur, Paris, exchange activity but its function was negatively regulated in a dose- France, 4Case Western Reserve University, Cleveland, OH, United States dependent manner by PfRPA1S, another RPA homologue in P. falciparum. Most studies of genetic diversity in Plasmodium vivax have focused We also present in vivo evidence through comet assays for methyl on microsatellites or selected loci and do not provide a genome-wide methanesulfonate (MMS)- induced DNA damage in malaria parasites perspective. We have sequenced the genomes of ten P. vivax field isolates www.astmh.org 151 collected across the world, and three monkey-adapted strains. We 504 sequenced each sample on one lane of an Illumina HiSeq 2000 to obtain 70-400X coverage and have >93% of the reference genome covered by TRACKING CHANGING POPULATION DYNAMICS OF >20 reads. We conservatively identified >85,000 SNPs across the genome PLASMODIUM FALCIPARUM INFECTIONS REVEALS EVIDENCE as well as several sequence rearrangements. The genetic diversity is OF CLONAL INFECTIONS FOLLOWING INTRODUCTION significantly higher in intergenic regions than in coding regions (6.84 vs. OF TRANSMISSION-REDUCING INTERVENTIONS IN THIÉS, 3.24 SNPs/kb) with intronic sequences harboring an intermediate level SENEGAL (4.63 SNPs/kb). We also observed 1.5-fold more non-synonymous than synonymous SNPs while, based on the genome composition, we would Rachel Daniels1, Hsiao-Han Chang2, Papa Diogoye Séne3, Daniel expect 4-fold more nsSNPs. These observations suggest that evolution of Park2, Jimmy Vareta4, Danny A. Milner5, Daria van Tyne1, Terrie E. most P. vivax protein-coding sequences is driven by purifying selection. To Taylor4, Souleymane Mboup3, Daouda Ndiaye3, Dyann F. Wirth1, identify genes evolving under positive selection, we compared the rates of Daniel L. Hartl6, Sarah K. Volkman1 non-synonymous (PN) and synonymous substitutions (PS) for all protein- 1Harvard School of Public Health, Boston, MA, United States, 2Harvard coding sequences. Two red blood cell binding protein genes, the Duffy University, Cambridge, MA, United States, 3Cheikh Anta Diop University, binding protein and the reticulocyte binding protein 2 like, were among Dakar, Senegal, 4University of Malawi College of Medicine, Blantyre, the ten genes with the highest PN/PS ratio