Person: Duraisingh, Manoj
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Duraisingh
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Manoj
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Duraisingh, Manoj
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Publication Functional Analysis of Sirtuin Genes in Multiple Plasmodium falciparum Strains(Public Library of Science, 2015) Merrick, Catherine J.; Jiang, Rays H. Y.; Skillman, Kristen; Samarakoon, Upeka; Moore, Rachel M.; Dzikowski, Ron; Ferdig, Michael T.; Duraisingh, ManojPlasmodium falciparum, the causative agent of severe human malaria, employs antigenic variation to avoid host immunity. Antigenic variation is achieved by transcriptional switching amongst polymorphic var genes, enforced by epigenetic modification of chromatin. The histone-modifying ‘sirtuin’ enzymes PfSir2a and PfSir2b have been implicated in this process. Disparate patterns of var expression have been reported in patient isolates as well as in cultured strains. We examined var expression in three commonly used laboratory strains (3D7, NF54 and FCR-3) in parallel. NF54 parasites express significantly lower levels of var genes compared to 3D7, despite the fact that 3D7 was originally a clone of the NF54 strain. To investigate whether this was linked to the expression of sirtuins, genetic disruption of both sirtuins was attempted in all three strains. No dramatic changes in var gene expression occurred in NF54 or FCR-3 following PfSir2b disruption, contrasting with previous observations in 3D7. In 3D7, complementation of the PfSir2a genetic disruption resulted in a significant decrease in previously-elevated var gene expression levels, but with the continued expression of multiple var genes. Finally, rearranged chromosomes were observed in the 3D7 PfSir2a knockout line. Our results focus on the potential for parasite genetic background to contribute to sirtuin function in regulating virulence gene expression and suggest a potential role for sirtuins in maintaining genome integrity.Publication Investigating the Pathogenesis of Severe Malaria: A Multidisciplinary and Cross-Geographical Approach(The American Society of Tropical Medicine and Hygiene, 2015) Wassmer, Samuel C.; Taylor, Terrie E.; Rathod, Pradipsinh K.; Mishra, Saroj K.; Mohanty, Sanjib; Arevalo-Herrera, Myriam; Duraisingh, Manoj; Smith, Joseph D.More than a century after the discovery of Plasmodium spp. parasites, the pathogenesis of severe malaria is still not well understood. The majority of malaria cases are caused by Plasmodium falciparum and Plasmodium vivax, which differ in virulence, red blood cell tropism, cytoadhesion of infected erythrocytes, and dormant liver hypnozoite stages. Cerebral malaria coma is one of the most severe manifestations of P. falciparum infection. Insights into its complex pathophysiology are emerging through a combination of autopsy, neuroimaging, parasite binding, and endothelial characterizations. Nevertheless, important questions remain regarding why some patients develop life-threatening conditions while the majority of P. falciparum-infected individuals do not, and why clinical presentations differ between children and adults. For P. vivax, there is renewed recognition of severe malaria, but an understanding of the factors influencing disease severity is limited and remains an important research topic. Shedding light on the underlying disease mechanisms will be necessary to implement effective diagnostic tools for identifying and classifying severe malaria syndromes and developing new therapeutic approaches for severe disease. This review highlights progress and outstanding questions in severe malaria pathophysiology and summarizes key areas of pathogenesis research within the International Centers of Excellence for Malaria Research program.Publication Genetic Evidence for Erythrocyte Receptor Glycophorin B Expression Levels Defining a Dominant Plasmodium falciparum Invasion Pathway into Human Erythrocytes(American Society for Microbiology, 2017) Dankwa, Selasi; Chaand, Mudit; Kanjee, Usheer; Jiang, Rays H. Y.; Nobre, Luis V.; Goldberg, Jonathan; Bei, Amy; Moechtar, Mischka A.; Gruring, Christof; Ahouidi, Ambroise D.; Ndiaye, Daouda; Dieye, Tandakha N.; Mboup, Souleymane; Weekes, Michael P.; Duraisingh, ManojABSTRACT Plasmodium falciparum, the parasite that causes the deadliest form of malaria, has evolved multiple proteins known as invasion ligands that bind to specific erythrocyte receptors to facilitate invasion of human erythrocytes. The EBA-175/glycophorin A (GPA) and Rh5/basigin ligand-receptor interactions, referred to as invasion pathways, have been the subject of intense study. In this study, we focused on the less-characterized sialic acid-containing receptors glycophorin B (GPB) and glycophorin C (GPC). Through bioinformatic analysis, we identified extensive variation in glycophorin B (GYPB) transcript levels in individuals from Benin, suggesting selection from malaria pressure. To elucidate the importance of the GPB and GPC receptors relative to the well-described EBA-175/GPA invasion pathway, we used an ex vivo erythrocyte culture system to decrease expression of GPA, GPB, or GPC via lentiviral short hairpin RNA transduction of erythroid progenitor cells, with global surface proteomic profiling. We assessed the efficiency of parasite invasion into knockdown cells using a panel of wild-type P. falciparum laboratory strains and invasion ligand knockout lines, as well as P. falciparum Senegalese clinical isolates and a short-term-culture-adapted strain. For this, we optimized an invasion assay suitable for use with small numbers of erythrocytes. We found that all laboratory strains and the majority of field strains tested were dependent on GPB expression level for invasion. The collective data suggest that the GPA and GPB receptors are of greater importance than the GPC receptor, supporting a hierarchy of erythrocyte receptor usage in P. falciparum.Publication Plasmodium falciparum CRK4 directs continuous rounds of DNA replication during schizogony(2017) Ganter, Markus; Goldberg, Jonathan; Dvorin, Jeffrey; Paulo, Joao; King, Jonas G.; Tripathi, Abhai K.; Paul, Aditya; Yang, Jing; Coppens, Isabelle; Jiang, Rays H.Y.; Elsworth, Brendan; Baker, David A.; Dinglasan, Rhoel R.; Gygi, Steven; Duraisingh, ManojPlasmodium parasites, the causative agents of malaria, have evolved a unique cell division cycle in the clinically relevant asexual blood-stage of infection1. DNA replication commences approximately halfway through the intracellular development following invasion and parasite growth. The schizont stage is associated with multiple rounds of DNA replication and nuclear division without cytokinesis resulting in a multinucleated cell. Nuclei divide asynchronously through schizogony, with only the final round of DNA replication and segregation being synchronous and coordinated with daughter cell assembly2,3. However, the control mechanisms for this divergent mode of replication are unknown. Here we show that the Plasmodium-specific kinase PfCRK4 is a key cell cycle regulator that orchestrates the multiple rounds of DNA replication throughout schizogony in P. falciparum. PfCRK4 depletion led to a complete block in nuclear division and profoundly inhibited DNA replication. Quantitative phosphoproteomic profiling identified a set of PfCRK4-regulated phosphoproteins with greatest functional similarity to CDK2 substrates, particularly proteins involved in origin of replication firing. PfCRK4 was required for the initial and subsequent rounds of DNA replication during schizogony, and in addition was essential for development in the mosquito vector. Our results identified an essential S phase promoting factor of the unconventional P. falciparum cell cycle. PfCRK4 is required for both a prolonged period of the intraerythrocytic blood-stage of malaria infection, as well as for transmission, revealing a broad window for PfCRK4-targeted chemotherapeutics.Publication Dietary restriction protects against experimental cerebral malaria via leptin modulation and T cell mTORC1 suppression(2014) Mejia, Pedro; Treviño-Villarreal, J. Humberto; Hine, Christopher; Harputlugil, Eylul; Lang, Samantha; Calay, Ediz; Rogers, Rick; Wirth, Dyann; Duraisingh, Manoj; Mitchell, JamesHost nutrition can affect the outcome of parasitic diseases through metabolic effects on host immunity and/or the parasite. Here we show that modulation of mouse immunometabolism through brief restriction of food intake (dietary restriction, DR) prevents neuropathology in experimental cerebral malaria (ECM). While no effects are detected on parasite growth, DR reduces parasite accumulation in peripheral tissues including brain, and increases clearance in the spleen. Leptin, a host-derived adipokine linking appetite, energy balance and immune function, is required for ECM pathology and its levels are reduced upon DR. Recombinant leptin abrogates DR benefits, while pharmacological or genetic inhibition of leptin signaling protects against ECM. DR reduces mTORC1 activity in T cells, and this effect is abrogated upon leptin administration. Furthermore, mTORC1 inhibition with rapamycin prevents ECM pathology. Our results suggest that leptin and mTORC1 provide a novel mechanistic link between nutrition, immunometabolism and ECM pathology, with potential therapeutic implications for cerebral malaria.Publication Insights into an Optimization of Plasmodium vivax Sal-1 In Vitro Culture: The Aotus Primate Model(Public Library of Science, 2016) Shaw-Saliba, Kathryn; Thomson-Luque, Richard; Obaldía, Nicanor; Nuñez, Marlon; Dutary, Sahir; Lim, Caeul; Barnes, Samantha; Kocken, Clemens H. M.; Duraisingh, Manoj; Adams, John H.; Pasini, Erica M.Malaria is one of the most significant tropical diseases, and of the Plasmodium species that cause human malaria, P. vivax is the most geographically widespread. However, P. vivax remains a relatively neglected human parasite since research is typically limited to laboratories with direct access to parasite isolates from endemic field settings or from non-human primate models. This restricted research capacity is in large part due to the lack of a continuous P. vivax in vitro culture system, which has hampered the ability for experimental research needed to gain biological knowledge and develop new therapies. Consequently, efforts to establish a long-term P. vivax culture system are confounded by our poor knowledge of the preferred host cell and essential nutrients needed for in vitro propagation. Reliance on very heterogeneous P. vivax field isolates makes it difficult to benchmark parasite characteristics and further complicates development of a robust and reliable culture method. In an effort to eliminate parasite variability as a complication, we used a well-defined Aotus-adapted P. vivax Sal-1 strain to empirically evaluate different short-term in vitro culture conditions and compare them with previous reported attempts at P. vivax in vitro culture Most importantly, we suggest that reticulocyte enrichment methods affect invasion efficiency and we identify stabilized forms of nutrients that appear beneficial for parasite growth, indicating that P. vivax may be extremely sensitive to waste products. Leuko-depletion methods did not significantly affect parasite development. Formatting changes such as shaking and static cultures did not seem to have a major impact while; in contrast, the starting haematocrit affected both parasite invasion and growth. These results support the continued use of Aotus-adapted Sal-1 for development of P. vivax laboratory methods; however, further experiments are needed to optimize culture conditions to support long-term parasite development.Publication Evidence for spleen dysfunction in malaria-HIV co-infection in a subset of pediatric patients(2015) Joice, Regina; Frantzreb, Charles; Pradham, Alana; Seydel, Karl B.; Kamiza, Steve; Wirth, Dyann; Duraisingh, Manoj; Molyneux, Malcolm E; Taylor, Terrie E.; Marti, Matthias; Milner, DannyThe spleen has an important role in the clearance of malaria parasites, and the role of HIV co-infection on this process is yet to be described. Using a combination of histological and molecular methods, we systematically evaluated parasite load across multiple organs from HIV-positive and HIV-negative cases of an autopsy study of pediatric comatose children with malaria infection (n = 103) in Blantyre, Malawi. Quantification of parasite load across organs was done using histology. A subset of cases was further characterized for parasite localization and stage of development using immunohistochemistry-based labeling of parasite and host cells (5 HIV-positive, 10 HIV-negative), and quantitative RT-PCR (qRT-PCR) of asexual and sexual-specific genes (4 HIV-positive, 5 HIV-negative). The results were compared with clinical information including HIV status. The HIV positive rate was 21% for the group studied (20 of 95) and HIV-positive patients had a significantly shorter duration of time between onset of illness and death, and were significantly older than HIV-negative patients. We found that spleens of HIV-positive cases had significantly higher parasite loads compared to those of HIV-negative cases in each the three methods we used: (i) standard histology, (ii) immunohistochemistry-based labeling of Plasmodium lactate dehydrogenase (pLDH), and (iii) molecular detection of asexual parasite transcript apical membrane antigen 1 (AMA1). Immunohistochemistry-based labeling of macrophage marker CD163 in a subset of spleens revealed fewer activated macrophages containing engulfed parasites and a greater number of free unphagocytosed parasites in the HIV-positive cases. The mechanism by which HIV infection is associated with more rapid progression to severe cerebral malaria disease is possibly impairment of parasite destruction by splenic macrophages, supported by published in vitro studies showing inefficient phagocytosis of malaria parasites by HIV-infected macrophages.Publication Enrichment of Reticulocytes from Whole Blood using Aqueous Multiphase Systems of Polymers(Wiley-Blackwell, 2014) Kumar, Ashok Ashwin; Lim, Caeul; Moreno, Yovany; Mace, Charles R.; Syed, Abeer; Van tyne, Daria; Wirth, Dyann; Duraisingh, Manoj; Whitesides, GeorgeThis paper demonstrates the enrichment of reticulocytes by centrifuging whole blood through aqueous multiphase systems (AMPSs)—immiscible phases of solutions of polymers that form step-gradients in density. The interfaces of an AMPS concentrate cells; this concentration facilitates the extraction of blood enriched for reticulocytes. AMPS enrich reticulocytes from blood from both healthy and hemochromatosis donors. Varying the osmolality and density of the phases of AMPS provides different levels of enrichment and yield of reticulocytes. A maximum enrichment of reticulocytemia of 64 ± 3% was obtained from donors with hemochromatosis. When used on peripheral blood from normal donors, AMPS can provide a higher yield of enriched reticulocytes and a higher proportion of reticulocytes expressing CD71 than differential centrifugation followed by centrifugation over Percoll. Blood enriched for reticulocytes by AMPS could be useful for research on malaria. Several species of malaria parasites show a preference to invade young erythrocytes and reticulocytes; this preference complicates in vitro cultivation of these species in human blood. Plasmodium knowlesi malaria parasites invade normal human blood enriched for reticulocytes by AMPSs at a rate 2.2 times greater (P < 0.01) than they invade unenriched blood. Parasite invasion in normal blood enriched by AMPS was 1.8 times greater (P < 0.05) than in blood enriched to a similar reticulocytemia by differential centrifugation followed by centrifugation over Percoll. The enrichment of reticulocytes that are invaded by malaria parasites demonstrates that AMPSs can provide a label-free method to enrich cells for biological research.Publication Altered drug susceptibility during host adaptation of a Plasmodium falciparum strain in a non-human primate model(Nature Publishing Group, 2016) Obaldía III, Nicanor; Dow, Geoffrey S.; Gerena, Lucia; Kyle, Dennis; Otero, William; Mantel, Pierre-Yves; Baro, Nicholas; Daniels, Rachel; Mukherjee, Angana; Childs, Lauren; Buckee, Caroline; Duraisingh, Manoj; Volkman, Sarah K.; Wirth, Dyann; Marti, MatthiasInfections with Plasmodium falciparum, the most pathogenic of the Plasmodium species affecting man, have been reduced in part due to artemisinin-based combination therapies. However, artemisinin resistant parasites have recently emerged in South-East Asia. Novel intervention strategies are therefore urgently needed to maintain the current momentum for control and elimination of this disease. In the present study we characterize the phenotypic and genetic properties of the multi drug resistant (MDR) P. falciparum Thai C2A parasite strain in the non-human Aotus primate model, and across multiple passages. Aotus infections with C2A failed to clear upon oral artesunate and mefloquine treatment alone or in combination, and ex vivo drug assays demonstrated reduction in drug susceptibility profiles in later Aotus passages. Further analysis revealed mutations in the pfcrt and pfdhfr loci and increased parasite multiplication rate (PMR) across passages, despite elevated pfmdr1 copy number. Altogether our experiments suggest alterations in parasite population structure and increased fitness during Aotus adaptation. We also present data of early treatment failures with an oral artemisinin combination therapy in a pre-artemisinin resistant P. falciparum Thai isolate in this animal model.Publication Demographic and clinical profiles of Plasmodium falciparum and Plasmodium vivax patients at a tertiary care centre in southwestern India(BioMed Central, 2016) Chery, Laura; Maki, Jennifer N.; Mascarenhas, Anjali; Walke, Jayashri T.; Gawas, Pooja; Almeida, Anvily; Fernandes, Mezia; Vaz, Marina; Ramanan, Rakesh; Shirodkar, Diksha; Bernabeu, Maria; Manoharan, Suresh Kumar; Pereira, Ligia; Dash, Rashmi; Sharma, Ambika; Shaik, Riaz Basha; Chakrabarti, Rimi; Babar, Prasad; White, John; Mudeppa, Devaraja G.; Kumar, Shiva; Zuo, Wenyun; Skillman, Kristen; Kanjee, Usheer; Lim, Caeul; Shaw-Saliba, Kathryn; Kumar, Ashwani; Valecha, Neena; Jindal, V. N.; Khandeparkar, Anar; Naik, Pradeep; Amonkar, Sunanda; Duraisingh, Manoj; Tuljapurkar, Shripad; Smith, Joseph D.; Dubhashi, Nagesh; Pinto, Roque G. W.; Silveria, Maria; Gomes, Edwin; Rathod, Pradipsinh K.Background: Malaria remains an important cause of morbidity and mortality in India. Though many comprehensive studies have been carried out in Africa and Southeast Asia to characterize and examine determinants of Plasmodium falciparum and Plasmodium vivax malaria pathogenesis, fewer have been conducted in India. Methods: A prospective study of malaria-positive individuals was conducted at Goa Medical College and Hospital (GMC) from 2012 to 2015 to identify demographic, diagnostic and clinical indicators associated with P. falciparum and P. vivax infection on univariate analysis. Results: Between 2012 and 2015, 74,571 febrile individuals, 6287 (8.4%) of whom were malaria positive, presented to GMC. The total number of malaria cases at GMC increased more than two-fold over four years, with both P. vivax and P. falciparum cases present year-round. Some 1116 malaria-positive individuals (mean age = 27, 91% male), 88.2% of whom were born outside of Goa and 51% of whom were construction workers, were enroled in the study. Of 1088 confirmed malaria-positive patients, 77.0% had P. vivax, 21.0% had P. falciparum and 2.0% had mixed malaria. Patients over 40 years of age and with P. falciparum infection were significantly (p < 0.001) more likely to be hospitalised than younger and P. vivax patients, respectively. While approximately equal percentages of hospitalised P. falciparum (76.6%) and P. vivax (78.9%) cases presented with at least one WHO severity indicator, a greater percentage of P. falciparum inpatients presented with at least two (43.9%, p < 0.05) and at least three (29.9%, p < 0.01) severity features. There were six deaths among the 182 hospitalised malaria positive patients, all of whom had P. falciparum. Conclusion: During the four year study period at GMC, the number of malaria cases increased substantially and the greatest burden of severe disease was contributed by P. falciparum.