Schistosomes are parasitic flatworms that cause a chronic, debilitating disease afflicting over 200 million people in over 70 countries. The parasites live for years, sometimes decades, in what should be a very hostile environment - the blood of vertebrates - yet they appear to solicit little if any protective reaction from two of the host's major defensive systems: the hemostatic system and the immune system. We hypothesize that proteins at the host-interactive surface are central to the parasites ability to dampen host immunity and hemostasis while, at the same time, permitting metabolite exchange. In this competing renewal, we propose to use new molecular methods such as RNA interference that were first developed for use with schistosomes under our previous grant, RO1 AI056273, to test several key hypotheses concerning: 1) the role of tegumental ecto-enzymes in hemostasis and immunomodulation, 2) the ability of tegumental sphingomyelinase to alter permeability properties at the parasite surface, and 3) the molecular mechanisms of trans- tegumental metabolite exchange. The functional genomics approach we adopt here coupled with independent and direct, follow-up experiments employing more traditional cell biology and biochemistry techniques are designed to provide significant new information concerning the schistosome host interactive surface. In addition the work is designed to identify tegumental proteins critical for parasite survival in the host and subsequent screens will be undertaken to discover drugs that inhibit these molecules. In this way, our planned experiments have the potential to reveal novel and valid targets, as well as new treatments, for intervention in a parasite that remains a widespread and major cause of human disease.

Public Health Relevance

Schistosomes are parasite worms that live in the blood streams of over 200 million people in more than 70 countries. These parasites are a major cause of death and disability worldwide. The worms have remarkable properties that allow them live inside people for many years. These properties include an ability to block our immune responses from targeting them, an ability to take in nutrients from our blood and an ability to detect environmental stresses and respond appropriately. By understanding more precisely how the parasites achieve these ends, we aim to block these capabilities and kill the worms.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Pathogenic Eukaryotes Study Section (PTHE)
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Wali, Tonu M
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Tufts University
Veterinary Sciences
Schools of Veterinary Medicine
United States
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Elzoheiry, Manal; Da'dara, Akram A; Bhardwaj, Rita et al. (2018) Intravascular Schistosoma mansoni Cleave the Host Immune and Hemostatic Signaling Molecule Sphingosine-1-Phosphate via Tegumental Alkaline Phosphatase. Front Immunol 9:1746
Wang, Qiang; Da'dara, Akram A; Skelly, Patrick J (2018) The blood fluke Schistosoma mansoni cleaves the coagulation protein high molecular weight kininogen (HK) but does not generate the vasodilator bradykinin. Parasit Vectors 11:182
Wang, Qiang; Da'dara, Akram A; Skelly, Patrick J (2017) The human blood parasite Schistosoma mansoni expresses extracellular tegumental calpains that cleave the blood clotting protein fibronectin. Sci Rep 7:12912
Krautz-Peterson, Greice; Debatis, Michelle; Tremblay, Jacqueline M et al. (2017) Schistosoma mansoni Infection of Mice, Rats and Humans Elicits a Strong Antibody Response to a Limited Number of Reduction-Sensitive Epitopes on Five Major Tegumental Membrane Proteins. PLoS Negl Trop Dis 11:e0005306
Da'dara, Akram A; Siddons, Giles; Icaza, Melissa et al. (2017) How schistosomes alter the human serum proteome. Mol Biochem Parasitol 215:40-46
Da'dara, Akram A; de Laforcade, Armelle M; Skelly, Patrick J (2016) The impact of schistosomes and schistosomiasis on murine blood coagulation and fibrinolysis as determined by thromboelastography (TEG). J Thromb Thrombolysis 41:671-7
Figueiredo, Barbara C; Da'dara, Akram A; Oliveira, Sergio C et al. (2015) Schistosomes Enhance Plasminogen Activation: The Role of Tegumental Enolase. PLoS Pathog 11:e1005335
Da'dara, Akram A; Skelly, Patrick J (2015) Gene suppression in schistosomes using RNAi. Methods Mol Biol 1201:143-64
Figueiredo, Barbara C; Assis, Natan R G; Morais, Suellen B et al. (2014) Schistosome syntenin partially protects vaccinated mice against Schistosoma mansoni infection. PLoS Negl Trop Dis 8:e3107
Da'dara, Akram A; Krautz-Peterson, Greice (2014) New insights into the reaction of Schistosoma mansoni cercaria to the human complement system. Parasitol Res 113:3685-96

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