Parasitology Commons^™

Advancing Trypanosoma Cruzi N-Myristoyltransferase As A Drug Target For Chagas Disease Through In Silico Discovery And Biochemical Evaluation, Diana Citlali González García

Open Access Theses & Dissertations

Chagas disease remains one of the most persistent and neglected parasitic infections in the Americas, advancing silently through the intracellular replication of Trypanosoma cruzi amastigotes and the invasive spread of trypomastigotes. The survival of the parasite is critically reliant on protein N-myristoylation, a lipid modification catalyzed by N-myristoyltransferase (NMT). This dissertation aims to advance beyond prior studies by systematically investigating NMT inhibition across multiple biological levels, spanning from the characterization of the purified enzyme, through cellular infection models, to the global proteomic remodeling induced within the parasite, thereby evaluating TcNMT as a potential therapeutic vulnerability in T.cruzi.Recombinant TcNMT was expressed, …

Novel Therapuetic Approaches For Chagas Disease, Juan Carlos Silva

Open Access Theses & Dissertations

Chagas disease (CD) is caused by the hemoflagellate protozoan Trypanosoma cruzi. This disease is considered one of the 20 neglected tropical diseases (NTD), and it is estimated that 6 to 8 million people worldwide are diagnosed with CD. In the United States, Chagas infection is not reported in all states; however, most reported CD cases are chronic infections. Chagas infection is characterized by two phases: an acute and a chronic phase. Until this present moment, no prophylactic or therapeutic human vaccine is available. However, in a recent study in a murine model, our group showed that the synthetic 20-merpeptide (DAENPGGEVFNDNKKGLSRV) …

Eluication Of Lipid Metabolic Pathways In Differentiating Giardia Lamblia Using High Resolution Mass Spectrometry, Cameron Ellis

Open Access Theses & Dissertations

Giardia lamblia is an intestinal protozoan found worldwide, including the U.S. This parasite exists in two morphologic stages - a replicative trophozoite and a relatively dormant yet viable cyst. While exposures of cysts to gastric acid during passage through the human stomach induces excystation, factors in the small intestine, where trophozoites colonize trigger encystation or cyst formation. Transformation into cyst stage is essential for Giardia to survive in the environment for months before infecting new hosts. Because of its small genome size (11.7 Mb), metabolic pathways in Giardia are highly reduced. As far as lipid metabolism is concerned, only limited …

Lipid Rafts, Exosomal Vesicles And Anti-Giardial Therapies, Brian Ivan Grajeda

Open Access Theses & Dissertations

Giardia lamblia, a protozoan parasite, is a major cause of waterborne infection, worldwide. While the trophozoite form of this parasite induces pathological symptoms in the gut, the cyst forms transmit the infection via contaminated water. Since Giardia is a non-invasive parasite, the actual mechanism by which it causes infection remains elusive. We have previously reported that Giardia assembles cholesterol and GM1 glycolipid-enriched lipid rafts (LRs) that participate in encystation and cyst production. To further delineate the role of LRs in pathogenesis, we isolated LRs from Giardia and subjected them to proteomic analysis. Various cellular proteins including the virulent proteins—e.g., giardins, …

Comprehensive Study Of Human Pathogenic Trypanosomatids: From Chemotherapies To Disease Ecology, Felipe Rodriguez

Open Access Theses & Dissertations

The vector-borne diseases Leishmaniasis and Chagas disease, caused by the kinetoplastid parasites Leishmania spp. and Trypanosoma cruzi respectively, are among the most important parasitic diseases in the group of neglected tropical diseases. Even though the two diseases are endemic to the Americas, they affect millions of people worldwide. Leishmaniasis and Chagas disease cause a great array of symptoms and some of them can be fatal if left undiagnosed and untreated. Current treatment regimens are becoming less effective, vaccines are still not available, and diagnosis needs to be improved. Vector control has been responsible for a decrease of diseases in endemic …

Molecular And Cellular Characterizations Of Glucosylceramide Transferase (Synthase) In Giardia Lamblia, Vanessa Enriquez

Open Access Theses & Dissertations

Giardiasis, caused by an intestinal protozoan, Giardia lamblia, is a major public health problem worldwide. Giardia infection is spread through the fecal-oral route via contaminated water and food. It is estimated that over 280 million people are infected with Giardia across the globe. Giardia is a non-invasive parasite and consists of a two-stage life cycle: trophozoites and cysts. Ingested cysts undergo excystation in the proximal small intestine, releasing two trophozoites (excyzoites). Upon reaching the distal small intestine and colonizing there, trophozoites transform into cysts by encystation. It has been reported earlier that the process of encystation induced the synThesis of …

In The Search For Novel Treatments For Chagas' Disease Using Cutting-Edge Imaging Technology, Karsten Dieter Amezcua Winter

Open Access Theses & Dissertations

Chagas disease (ChD) is caused by Trypanosoma cruzi (T. cruzi), an intracellular protozoan parasite. ChD has a global mortality of 15,000 annual deaths, and approximately, 8-10 million people are infected. There is growing concern in the United States as autochthonous cases of ChD have been reported in the southern region. The two available treatments are only partially effective and highly toxic. N-aroyl derivatives and α, β-unsaturated ketones have been previously tested against Leishmania, a closely related parasite, demonstrating selective toxicity towards the microorganism. The objective of this study is to evaluate a drug library consisting of 21 α, β-unsaturated ketones …

Expression And Functional Sialome Of Triatomines, Insect Vectors Of Chagas Disease, Maria Tays Mendes

Open Access Theses & Dissertations

Triatomines are blood-sucking arthropods that transmit Trypanosoma cruzi, the etiologic agent of Chagas disease (ChD). Triatomines use bioactive molecules in the saliva for successful blood feeding and to evade the hemostatic and immune defense system of the hosts. Knowing the saliva composition could be useful for a better understanding which and how insect-derived molecules might influence host-parasite interactions. Previous studies have shown that some saliva-derived proteins and lipids can modulate the host immune system and increase T. cruzi infection. We hypothesize that the triatomine saliva contains a great diversity of lipids and proteins that can modulate the mammalian host immune …

Trypanosoma Cruzi Trypomastigote Glycosylphosphatidylinositol-Anchored Mucins And A Synthetic Alpha-Gal-Containing Neoglycoprotein As Potential Biomarkers And Vaccines For Chagas Disease, Igor Leandro Estevao

Open Access Theses & Dissertations

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a neglected tropical disease that kills or permanently disable thousands of people annually. About 6-8 million people are estimated to be infected worldwide. Although many efforts have been made for the development of an effective immunotherapy, currently there is no vaccine to prevent or treat CD in humans. Despite their toxicity, the two current drugs for CD, benznidazole (BZN) and nifurtimox (NFX), have medium-to-high efficacy in the chronic stage of the disease and could save or improve the lives of thousands of patients. However, negative seroconversion in treated patients, as …

Crispr/Cas9-Induced Genetic Disruption And Characterization Of Udp-Galactopyranose Mutase In Trypanosoma Cruzi, Claudia Manriquez

Open Access Theses & Dissertations

The protozoan parasite, Trypanosoma cruzi, is the causative agent of Chagas disease (ChD), or American trypanosomiasis, which affects 6-8 million people in Latin America. It is estimated that 2-3 million people will develop severe lifelong cardiac and/or digestive disorders. ChD has become a life threat not only to endemic regions but most recently also to nonendemic regions, including the United States, owing to extensive worldwide migration in recent years. The lack of a vaccine and the limited efficacy of the two drug treatments available make it urgent to develop novel therapies to treat such a threatening disease. UDP-Galactopyranose mutase (UGM) …

Novel Possibilities For The Treatment And Prevention Of Cutaneous Leishmaniasis, Eva A. Iniguez

Open Access Theses & Dissertations

Protozoan parasites from the genus Leishmania cause broad clinical manifestations known as leishmaniasis, which affect millions of people worldwide. Cutaneous leishmaniasis (CL) is mainly caused by either Leishmania major or L. tropica parasites, which produce localized cutaneous ulcers, often leading to scarring and social stigma. Currently, the disease has reached hyperendemicity levels in the Middle East due to conflict and human displacement and is one the most common forms of the disease in the Old World. Furthermore, the first choice of treatment in that region continues to be pentavalent antimonials, which are costly and highly toxic, and current vector control …

Detecting Enzootic Leishmaniasis And American Trypanosomiasis In Stray Dogs In El Paso County, Texas And The Potential For Autochthonous Transmission To Humans, Evan James Kipp

Open Access Theses & Dissertations

Cutaneous leishmaniasis and Chagas disease (American trypanosomiasis) are two vector-borne, protozoal zoonoses whose emergence into the southern United States is a public health problem of increasing significance. Cutaneous leishmaniasis is caused by several species of intracellular protozoa in the genus Leishmania and is most often characterized by the formation of large, ulcerative skin lesions that can result in considerable scarring and permanent disfigurement. Infection with Leishmania is prevalent throughout the world in tropical and sub-tropical regions and in areas where people are regularly exposed to the hematophagous sand fly vectors that transmit the disease. Chronic infection with Trypanosoma cruzi, the …

Serine Palmitoyltransferase And Giardial Encystation, Monica Delgado

Open Access Theses & Dissertations

Giardia lamblia is a flagellated protozoan parasite responsible for chronic diarrheal disease in humans and animals. Giardia has minimal lipid synThesis machinery and the majority of its lipids are obtained from the small intestine of humans where the trophozoites colonize. Recent results from our laboratory indicate that sphingolipids (SLs) are also important for Giardia and they regulate encystation and cyst production. Only five SL genes are present in this parasite and they are differentially regulated during encystation. In my studies, I found that giardial serine palmitoyltransferase (gSPT) activity is upregulated in encysting cells, suggesting it might play an important role …

Global Sphingolipid Profile Of Giardia Lamblia During Stage Differentiation: The Influence Of Sphingomyelin Abundance On Viable Cyst Production, Trevor Thomas Duarte

Open Access Theses & Dissertations

Giardia lamblia is a protozoan parasite and a major cause of the waterborne-illness, giardiasis, worldwide. Giardiasis is endemic in developing countries and is a leading cause of non-viral- and non-bacterial-associated intestinal disorders. Acute symptoms of giardiasis include diarrhea, cramps, and malabsorption. The disease is often self-limiting, although the infection can result in long-term disorders such as chronic fatigue, stunted cognitive skills, and failure to thrive even after the parasite has been cleared.

This parasite exists in two morphologic forms--infective trophozoites and transmissible, water-resistant cyst, which is passed by the fecal-oral route and is likely to be spread by contaminated drinking …

Ruthenium-Azole Complexes As Chemotherapeutic Agents Against Leishmaniasis, Eva Iniguez

Open Access Theses & Dissertations

Leishmaniasis is a neglected disease that affects millions of people worldwide. Poor efficacy and high toxicity of the limited treatment options demonstrate the need for the development of new chemotherapeutic agents to treat this disease. In order to respond this concern, the development of novel Ru-azole complexes as chemotherapeutic agents by inhibiting the cytochrome P-450 dependent C14-α-demethylation of lanosterol to ergosterol which is essential for the parasite survival. In addition, Ruthenium would enhance the activity of the parental drug, by helping ketoconazole/clotrimazole to cross the parasite membrane, together presenting low toxicity. The viability and citotoxicity of the Ru-azole compunds was …

Validation Of N-Myristoyltransferase As Potential Chemotherapeutic Target In Chagas Disease, Linda Herrera

Open Access Theses & Dissertations

The protozoan parasite Trypanosoma cruzi is the etiological agent of Chagas disease, a problem endemic to Central and South America. In recent years, this neglected infectious disease has become a global health concern. The only clinically available drugs for the chemotherapy of Chagas disease have important disadvantages such as, high toxicity, strain resistance and variable efficacy. Therefore, there is an urgent need for the development of new antichagasic agents. The enzyme N-myristoyltransferase (NMT) has been characterized in a range of eukaryotes, from Saccharomyces cerevisae to Homo sapiens. Moreover, NMT has been shown to be essential in protozoan parasites, including Leishmania …

Giardia Lamblia: Regulation Of Cyst Production By Glycosphingolipids, Tavis Lyle Mendez

Open Access Theses & Dissertations

The diplomonad protist, Giardia lamblia, colonizes and replicates in the small intestine of mammals. In humans, Giardia infection (known as giardiasis) can be symptomatic or asymptomatic with the former being associated with fatty stool, abdominal pain, malnutrition, and weight loss. Both cell-mediated and humoral immune responses against Giardia infection are possible, and adaptive responses have been reported to be important for controlling the infection. Non-immune components such as secretory immunoglobulin, intestinal lipids, and bile acids also play significant roles in determining the severity of the infection by Giardia.

Giardia exists in two morphologic forms--trophozoites and cysts--and maintains a simple life …

Mucin Associated Surface Protein Synthetic Peptide As A Novel Vaccine Candidate Against Chagas Disease, Carylinda Serna

Open Access Theses & Dissertations

Trypanosoma cruzi is an intracellular protozoan parasite and the etiological agent for Chagas disease. Chagas is endemic in Latin America affecting 18-20 million people. However, currently worldwide increasing numbers of the disease are being seen due to migration and globalization. This neglected disease causes significant morbidity, mortality, and an economic burden. There are no known vaccines and the only currently available drug is Benznidazole, but its effects are controversial. Nonetheless, a therapeutic or prophylactic vaccine is of urgent need to alleviate this disease. In this study we present an experimental approach using a synthetic peptide-based vaccine against T. cruzi. The …

Identification Of Chemotherapeutic Agents Against Leishmaniasis And Chagas' Disease, Miguel Abran Vasquez

Open Access Theses & Dissertations

Patients with clinical manifestations of leishmaniasis and Chagas' disease rely on few drugs that have limited efficacy and considerable side effects. Expanding the diversity of available chemotherapeutic drugs for these diseases is of extreme medical importance. Enones or á,í¢-unsaturated ketones, initially developed as anti-cancer agents, are a worthy of class of compounds to test for activity against Leishmania major and Trypanosoma cruzi as these eukaryotic parasites share many of the characteristics exhibited by cancer cells. The anti-parasitic activity of a library of á,í¢-unsaturated ketones (136 derivatives) was screened against L. major as well as in mammalian cells. Three compounds (NC901, …

Development Of A Novel Metallo-Lipid Microparticle Delivery System For A Leishmania Mexicana Dna Vaccine Candidate, Joanna B. Valencia

Open Access Theses & Dissertations

ABSTRACT

Background and Significance.

The leishmaniases are an important group of neglected tropical parasitic diseases caused by parasitic protozoa of the genus Leishmania. International health authorities estimate that 350 million people around the world are at risk for contracting leishmaniasis. Two million new cases occur each year and 12 million people are presently infected worldwide. Leishmaniasis is endemic throughout the Americas region including all of Central America, most of South America, Mexico and southern Texas. Leishmania is also considered a threat to the military readiness of U.S. troops deployed to the Middle East or Latin America.

First- and second-line treatments …

The Interplay Between Host Cells And The Human Pathogen Trypanosoma Cruzi: Role Of Toll-Like Receptors, Lilian Lie Nohara

Open Access Theses & Dissertations

The protozoan parasite Trypanosoma cruzi is the etiologic agent of Chagas disease, a neglected infectious disease that is becoming a world health concern. This obligate intracellular parasite employs a diversity of molecules and strategies to successfully invade a wide variety of mammalian cells and modulate host immune responses, which are essential features for completion of its life cycle in the host. The major plasma membrane antigens of T. cruzi infective trypomastigote forms are glycosylphosphatidylinositol (tGPI)-anchored mucin-like glycoproteins. Although previous studies demonstrated that the proinflammatory responses induced by tGPIs are mediated by Toll-like receptor (TLR) 2, the involvement of other TLRs …

Lipid Uptake And Metabolism In The Parasitic Protozoan Giardia Lamblia., Mayte Yichoy

Open Access Theses & Dissertations

Giardia lamblia is a protozoan parasite that causes various intestinal syndromes, and it is a common cause of water-borne illness worldwide, both in developed and developing countries. Giardia attaches to the mucosal epithelia of the duodenum below the bile duct, where it is exposed to bile salts and dietary lipids. G. lamblia is unable to synthesize lipids de novo and must therefore scavenge necessary lipids from its extracellular environment and remodel them as needed. However, the current lipidomic analysis (presented in this Dissertation) has revealed that while the Giardia lipidome is rich in phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG), …

Molecular Characterization Of Trypanosoma Cruzi And Shed Vesicle Components Involved In Host Immunomodulation And Cell Invasion, Ernesto Satoshi Nakayasu

Open Access Theses & Dissertations

Chagas disease caused by Trypanosoma cruzi is a devastating infectious disease with millions of cases in Latin America, and recently became a public health concern in United States and Europe. Although many efforts have been made for the development of an effective immunotherapy, currently there is no human vaccine for Chagas disease. Thus, the treatment is based only on two drugs that have limited efficacy and in some cases present severe side effects. One restriction for the rational approach to develop new therapies against this disease is the limited information about the proteins, glycolipids and protein posttranslational modifications expressed by …

Giardia Lamblia: Genomic And Molecular Analyses Of Flippase, Diana Leticia Villazana-Kretzer

Open Access Theses & Dissertations

Giardia lamblia, is an intestinal protozoan parasite responsible as a major cause of water-borne intestinal infection in humans (giardiasis). It has been proposed earlier that Giardia has limited lipid synThesis ability and therefore relies on preformed lipid molecules from outside sources. It has also been proposed that lipids are taken up through passive and active transport, and giardial flippasse play a significant role in this process. This study describes the identification and characterization of a putative homologue of flippase gene from Giardia. Flippase is an enzyme that functions as a trans-bilayer transport system facilitating the flip flop diffusion of phospholipids …