Life Sciences Commons^™

Plasmodium Suppresses T Cell Responses To Heterologous Infections By Impairing T Cell Activation, Chelsi Elizabeth White

Masters Theses

Malaria is a devastating disease caused by parasites of the genus Plasmodium. Plasmodium falciparum, which is responsible for most malaria related fatalities, suppresses host immune responses during heterologous coinfections or following vaccination. However the mechanisms responsible for this defect are not well defined. The mechanism and to what extent this immunosuppression is occurring was investigated. This study demonstrates that both dendritic cell and T cell activation are impaired following a Plasmodium infection, ultimately altering the adaptive T cell response to secondary infections. T cell suppression is evident early on following a secondary infection and continues throughout the peak of parasitemia. …

Modeling Leafhopper Populations And Their Role In Transmitting Plant Diseases., Ji Ruan

Electronic Thesis and Dissertation Repository

This M.Sc. thesis focuses on the interactions between crops and leafhoppers.

Firstly, a general delay differential equations system is proposed, based on the infection age structure, to investigate disease dynamics when disease latencies are considered. To further the understanding on the subject, a specific model is then introduced. The basic reproduction numbers $\cR_0$ and $\cR_1$ are identified and their threshold properties are discussed. When $\cR_0 < 1$, the insect-free equilibrium is globally asymptotically stable. When $\cR_0 > 1$ and $\cR_1 < 1$, the disease-free equilibrium exists and is locally asymptotically stable. When $\cR_1>1$, the disease will persist.

Secondly, we derive another general delay differential equations system to examine how different life stages of leafhoppers affect crops. The basic reproduction numbers $\cR_0$ is determined: when …

Microsporidia Spore Adherence And Host Cell Infection In Vitro, Cory A. Leonard

Electronic Theses and Dissertations

Microsporidia infect invertebrate and vertebrate animals. Human pathogenic microsporidia are associated with severe disease in immunocompromised individuals, and mostly asymptomatic infection in the immunocompetent. Treatment options for microsporidiosis are limited, incompletely effective, and associated with toxicity. Furthermore, microsporidia infection of healthy individuals is poorly understood, and the consequences of asymptomatic infection have not been determined. Little is known about the molecular mechanisms of microsporidia infection, but such information is essential for the development of new therapies. Spores adhere to host cell surfaces in vitro. Our laboratory has focused on determining specific host cell and microsporidia spore surface participants in spore …

Trends In Borrelia Spp. Prevalence In Ixodes Spp. Ticks From The Southeastern Coastal United States, Lauren Paul Maestas

Masters Theses

The Lyme borreliosis (LB) cycle, involving Ixodes scapularis and Borrelia burgdorferi sensu stricto (Bbss), is well documented in the northeastern US, where LB is becoming increasingly prevalent. In coastal North Carolina, I. affinis has been shown to have a higher incidence of Bbss than I. scapularis. My objectives were, to assess changes in prevalence of Bbss in Ixodes spp. along a transect from Virginia to Florida, and to assess the value of dogs and mesomammals as sentinels for spread of Borrelia burgdorferi sensu lato.

Ixodes spp. were collected at sites from 37.4^o N to 30.0^{o …}

Prevalence And Transmission Potential Of Borrelia Burgdorferi In Three Species Of Wildcaught Plestiodon Spp. Skinks Of The Southeastern United States, Teresa Dianne Moody

Masters Theses

In the southeastern United States, blue-tailed skinks (Plestiodon spp.) are important hosts for Ixodes scapularis ticks, the principal vector of Lyme disease (LD) in this region. Skinks and other southeastern lizards are not thought to be reservoir competent for Borrelia burgdorferi sensu stricto (Bbss), the etiological agent of LD in the United States. . Lizard-feeding by southeastern I. scapularis may tend to suppress sylvatic cycles of B. burgdorferi, and thus may be an important reason why LD case rates in the Southeast are much lower than in the Northeast and upper Midwest. Nevertheless, some skinks …

Efficacies Of Fenbendazole And Albendazole In The Treatment Of Commercial Turkeys Artificially Infected With Ascaridiadissimilis, Jessica Perkins

Animal Science Undergraduate Honors Theses

The goal of this research was to determine the extent of anthelmintic resistance that turkey roundworms, Ascaridiadissimilis, have developed to anti-parasitic chemicals used in commercial turkey operations. Roundworm infections in turkeys have resulted in monetary losses for the poultry industry for years, generally due to poor feed conversion. The infection itself is generally subclinical and many turkeys have a light to moderate worm burden. Since parasitisms are light, this leads to the infections being noticed only during processing.A. dissimilis infections consist of adult worms and developing larvae with the latter comprising most of the worm burden and causing the most …

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, …

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 …

Detection Of Antibodies Against Parascaris Equorum Excretory-Secretory Antigens, Steffanie V. Burk

Theses and Dissertations--Animal and Food Sciences

Parascaris equorum is a nematode parasite that infects young horses, sometimes causing unthriftiness, respiratory signs, or intestinal impaction in severe cases. Infection can be diagnosed by detection of eggs in feces, but this is only possible after the worms are fully mature. The goal of this study was to develop an antibody-based test for prepatent diagnosis of P. equorum infection. To produce western blot (WB) antigen, P. equorum larvae were cultured for collection of excretory-secretory antigens (ESA). Sera from 18 pregnant broodmares, their subsequent foals, and a group of 12 older mares and geldings were analyzed. In order to check …

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 …

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 …

Relationship Between Dysphoric Moods, Risk-Taking Behaviors, And Toxoplasma Gondii Antibody Titers In Female Veterans, Allyson Radford Duffy

USF Tampa Graduate Theses and Dissertations

The number of female veterans is increasing daily. Previous research conducted on veterans has focused primarily on males or with small samples of females. Depression and suicidality are becoming increasingly evident in returning veterans. Toxoplasma gondii is an intracellular parasite that is common in the Middle East and has been reported to cause changes in personality and behavior.

The purpose of the current study was to examine relationships between T. gondii antibody titer and socioeconomic variables, dysphoric moods, and risk-taking behaviors in a sample of 70 female veterans. Blood samples were collected and analyzed for T. gondii antibody titer and …

Phenotypic And Genotypic Analysis Of In Vitro Selected Miltefosine Resistant Leishmania Donovani, Brian A. Vesely

USF Tampa Graduate Theses and Dissertations

Abstract

Visceral leishmaniasis is a devastating neglected parasitic disease caused by infection with Leishmania donovani. It life cycle has two stages with promastigote (insect stage) and amastigote (animal stage) morphologies. Miltefosine is currently the only commercially available oral drug available to treat leishmaniasis and recent evidence suggests clinical resistance has emerged. Due to the importance of this drug and the scarcity of new drugs in the pipeline, work has been done on understanding the mechanism(s) of miltefosine, yet the mechanism of action for resistance is still not known.

In previous studies investigators generated miltefosine resistance on the insect vector stage …

Parasites Of Invasive Carp And Native Fish In The Wabash River, Justin Wilcox

Masters Theses

Although the majority of introduced non-native species fail to establish, proliferate and spread to the point of causing observable damage, there are a significant minority that achieve biological successes far beyond what they do in their native ranges. Parasites and pathogens are theorized to play an important role in determining the outcome of invasions by non-native species, both as potential mediators of the population growth of invasive species and as invasive species themselves. This study examines and compares the abundance and species richness of digestive tract helminths in native and non-native fish of the lower Wabash River, a single waterpool …

Understanding Amphibian Decline: The Role Of Pesticides And The Pathogenic Chytrid Fungus On Amphibians And Aquatic Communities, Taegan A. Mcmahon

USF Tampa Graduate Theses and Dissertations

Amphibians are the most threatened taxon on the planet. Declines have been associated with over-exploitation, habitat loss, pollution, and pathogenic diseases, but of these factors, pollution and disease have been relatively under-studied. Here, I investigated: 1) the impacts of commonly used pesticides on aquatic communities, 2) the effect of these pesticides on amphibian susceptibility to the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), and 3) whether there are non-amphibian hosts of Bd and 4) how to best quantify the survival of Bd through ontogeny of the host.

In my first research chapter, I quantified the effects of environmentally relevant concentrations of …