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Full-Text Articles in Pathogenic Microbiology

The Identification Of Small Molecule Inhibitors To Candida Albicans Phosphatidylserine Synthase, Yue Zhou Dec 2023

The Identification Of Small Molecule Inhibitors To Candida Albicans Phosphatidylserine Synthase, Yue Zhou

Doctoral Dissertations

Candida albicans phosphatidylserine (PS) synthase, encoded by the CHO1 gene, has been identified as a potential drug target for new antifungals against systemic candidiasis due to its importance in virulence, absence in the host and conservation among fungal pathogens. This dissertation is focused on the identification of inhibitors for this membrane enzyme. Cho1 has two substrates: cytidyldiphosphate-diacylglycerol (CDP-DAG) and serine. Previous studies identified a conserved CDP-alcohol phosphotransferase (CAPT) binding motif present within Cho1, and here we revealed that mutations in all but one conserved amino acid within the CAPT motif resulted in decreased Cho1. For serine, we have predicted a …


Induction And Evasion Of Neutrophil Extracellular Traps By Campylobacter Jejuni And Its Implication In Disease, Sean M. Callahan May 2023

Induction And Evasion Of Neutrophil Extracellular Traps By Campylobacter Jejuni And Its Implication In Disease, Sean M. Callahan

Doctoral Dissertations

Campylobacteriosis, the foodborne disease caused by Campylobacter spp., infects one out of 10 individuals every year. C. jejuni accounts for 90% of these infections resulting in numerous postinfectious disorders including the development of colorectal cancer, Guillain-Barré syndrome, irritable bowel syndrome, and reactive arthritis. Despite its large impact on human health, the host immune response to the bacterium is largely uncharacterized. Chapter two of this dissertation addresses the development of neutrophil extracellular traps (NETs) within human and ferret campylobacteriosis. We observed NET-associated proteins increase in the feces of C. jejuni-infected patients and that in vitro C. jejuni induces NETs, which …


Cat Covid, Cmv And Chemokines, Oh My!, Trevor Hancock May 2022

Cat Covid, Cmv And Chemokines, Oh My!, Trevor Hancock

Doctoral Dissertations

Cytomegalovirus (CMV) is an important pathogen infecting most humans worldwide. CMV infection within immunocompromised individuals can cause severe morbidity and potential mortality. Disease during CMV infection is due to virus dissemination and subsequent inflammation. Host immune cells lie at the intersection potentially mediating both. The CMV-encoded viral chemokine vCXCL-1 is a proposed virulence factor in mouse models increasing immune cell recruitment and disease. However, the primary immune cell mediator is undetermined. To identify targets, Chapter 2 examines CXCR2 expression (receptor for vCXCL-1) among various mouse tissues and human peripheral blood under steady-state conditions. In vitro, isoforms of HCMV’s vCXCL-1 …


Mechanisms By Which Xenorhabdus Nematophila Interacts With Hosts Using Integrated -Omics Approaches, Nicholas C. Mucci May 2022

Mechanisms By Which Xenorhabdus Nematophila Interacts With Hosts Using Integrated -Omics Approaches, Nicholas C. Mucci

Doctoral Dissertations

Nearly all organisms exist in proximity to microbes. These microbes perform most of the essential metabolic processes necessary for homeostasis, forming the nearly hidden support system of Earth. Microbial symbiosis, which is defined as the long-term physical association between host and microbes, relies on communication between the microbial community and their host organism. These interactions among higher order organisms (such as animals, plants, and fungi) and their bacteria links metabolic processes between interkingdom consortia. Many questions on microbial behavior within a host remain poorly understood, such as the colonization efficiency among different microbial species, or how environmental context changes their …


Antibiotic Resistance, A Global Pandemic, Deneil Patel May 2021

Antibiotic Resistance, A Global Pandemic, Deneil Patel

Chancellor’s Honors Program Projects

No abstract provided.


Optimization Of Rt-Qpcr Protocols To Quantify Chua Gene Expression In Campylobacter Jejuni Mutants Under Iron-Limited Conditions, Jacob D. Wilbert May 2020

Optimization Of Rt-Qpcr Protocols To Quantify Chua Gene Expression In Campylobacter Jejuni Mutants Under Iron-Limited Conditions, Jacob D. Wilbert

Chancellor’s Honors Program Projects

No abstract provided.


Switchgrass Extractives Have Potential As A Value-Added Antimicrobial Against Plant Pathogens And Foodborne Pathogens, Alexander Ian Bruce Dec 2016

Switchgrass Extractives Have Potential As A Value-Added Antimicrobial Against Plant Pathogens And Foodborne Pathogens, Alexander Ian Bruce

Masters Theses

Panicum virgatum (switchgrass), a perennial grass native to North America, is a leading biomass feedstock candidate for the manufacture of cellulosic ethanol. Switchgrass is considered a viable option for biofuel production due to its cheap production cost and ability to grow on marginal land. Biofuel derived from switchgrass has been shown to be very energy efficient, producing 540% more renewable energy versus nonrenewable energy expended. Switchgrass-derived biofuel is also estimated to have greenhouse gas emissions that are 94% lower than emissions from gasoline (Schmer et al 2008). Biofuels are created through biochemical processes that utilize various enzymes and microorganisms for …


Multilayered Regulation Of The Type I Toxin Zoro In Ehec, Jia Wen Aug 2016

Multilayered Regulation Of The Type I Toxin Zoro In Ehec, Jia Wen

Doctoral Dissertations

A bacterial type I toxin-antitoxin system contains two genes: one encodes a small toxic protein and the second, a small regulatory RNA (sRNA) that inhibits toxin production. To date, very few type I loci have been described thoroughly in regards to the regulation of toxin and the function of the toxin at endogenous levels. In this study, I demonstrated that the zor-orz locus of Escherichia coli O157:H7 is composed of two highly homologous type I toxin-antitoxin systems: zorO-orzO and zorP-orzP. The zor genes encode the toxins and the orz genes encode the antitoxin sRNAs. Overexpression of zorO is toxic …


The Role Of Phosphatidylserine And Phosphatidylethanolamine In Candida Albicans Virulence, Sarah Elizabeth Davis Aug 2015

The Role Of Phosphatidylserine And Phosphatidylethanolamine In Candida Albicans Virulence, Sarah Elizabeth Davis

Doctoral Dissertations

In hospitalized patients with neutropenia, Candida albicans is the fourth leading cause of systemic bloodstream infections, which have a mortality rate of approximately 30 %. The phosphatidylserine synthase enzyme of C. albicans, Cho1p, appears to be a good drug target as a mutant lacking this enzyme (the cho1Δ/Δ [null mutant]) is avirulent in animal models of Candida infections and this enzyme is not conserved in humans. We discovered that the loss of phosphatidylserine (PS) synthesis affects C. albicans' expression of the Als3p adhesin, a virulence protein, and loss of PS synthesis also compromises the cell wall, causing increased …


Genetic Diversity, Population Structure, And Evolution Of Virulence In Toxoplasma Gondii, Elliot Keats Cullen Shwab May 2015

Genetic Diversity, Population Structure, And Evolution Of Virulence In Toxoplasma Gondii, Elliot Keats Cullen Shwab

Doctoral Dissertations

Toxoplasma gondii is among the most widespread eukaryotic pathogens known. It chronically infects approximately one third of the world’s human population and has been isolated from an extremely diverse array of globally distributed mammals and birds. Understanding the structure of the worldwide T. gondii population enhances our understanding of the factors that have shaped that structure and led to the proliferation of one of the most evolutionarily successful pathogens on Earth. Herein we collate genotypic data from global isolates, demonstrating that T. gondii possesses a unique population structure in which only a small number of genotypes dominate throughout the northern …


Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares May 2015

Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares

Doctoral Dissertations

Emerging non-O157 Shiga toxin-producing Escherichia coli (STEC) were recently added to the zero tolerance policy by the USDA-FSIS. Therefore, the precise characterization of their thermal inactivation kinetics in different foods and the effect of stress on thermal inactivation are needed. This research aimed at determining the heat inactivation kinetics of non-O157 and O157 STECs in buffer and model food matrices and the effects of DnaK levels on thermal resistance after acid and heat-shock. Thermal inactivation was carried out in either in 2-ml glass vials or nylon vacuum-sealed bags for buffer and food (spinach, ground-beef, turkey deli-meat, pasta) samples, respectively. Vials …


Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood Dec 2014

Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood

Doctoral Dissertations

Microbial chemotaxis receptors (chemoreceptors) are complex proteins that sense the external environment and signal for flagella-mediated motility, serving as the GPS of the cell. In order to sense a myriad of physicochemical signals and adapt to diverse environmental niches, sensory regions of chemoreceptors are frenetically duplicated, mutated, or lost. Conversely, the chemoreceptor signaling region is a highly conserved protein domain. Extreme conservation of this domain is necessary because it determines very specific helical secondary, tertiary, and quaternary structures of the protein while simultaneously choreographing a network of interactions with the adaptor protein CheW and the histidine kinase CheA. This dichotomous …


Investigation Into Potential Cross-Resistance Of Enterococcus Faecalis Og1rf Induced By Adaptation To Nacl And Subsequent Sds Challenge, Vidisha Singh Dec 2012

Investigation Into Potential Cross-Resistance Of Enterococcus Faecalis Og1rf Induced By Adaptation To Nacl And Subsequent Sds Challenge, Vidisha Singh

Chancellor’s Honors Program Projects

No abstract provided.


Efficacy Of Biopesticides For Organic Management Of Cucumber Beetles, Mary A. Rogers Dec 2012

Efficacy Of Biopesticides For Organic Management Of Cucumber Beetles, Mary A. Rogers

Doctoral Dissertations

Organic growers are limited in crop protection techniques for cucumber beetle management. Spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vitatta) cucumber beetles and are significant pests of cucurbits in the U.S. Feeding results in aesthetic damage and reduction in marketable yields as well as transmission of bacterial wilt that can result in plant mortality. Biopesticides are products formulated from naturally occurring organisms such as fungi and bacteria that are pathogenic or toxic to insect pests. Advantages to these products are that they have low environmental risk, low risk to non-target organisms including mammals and beneficial insects, …


Fatty Acid Synthase 1 In Candida Albicans Virulence And The In Vitro Effects Of Fluconazole, Tetracycline In Combinatorial Therapy, Marissa Mandy Rodrigues Dec 2012

Fatty Acid Synthase 1 In Candida Albicans Virulence And The In Vitro Effects Of Fluconazole, Tetracycline In Combinatorial Therapy, Marissa Mandy Rodrigues

Masters Theses

Candida albicans, the causative agent of superficial and invasive mycoses, is a significant fungal pathogen associated with high mortality rates and considerable health-related costs. The most effective class of antifungals used for the treatment of candidiasis includes polyenes, echinocandins and azoles. However with the emergence of resistant strains, new antifungals are warranted for the effective treatment of candidiasis. Genes involved in biosynthetic enzymatic pathways that regulate metabolic processes are important for the survival of pathogenic fungi and can thus be exploited for the development of better antifungals. Fatty acid synthase 1, which is involved in the de novo biosynthesis of …


Investigation Of Host Responses Upon Infection Of Distinct Toxoplasma Strains, Rachel Devonne Hill Dec 2011

Investigation Of Host Responses Upon Infection Of Distinct Toxoplasma Strains, Rachel Devonne Hill

Doctoral Dissertations

Toxoplasma gondii is the causative agent of Toxoplasmosis in human and animals. T. gondii isolates are highly diverse. Hundreds of genotypes have been identified, but only three clonal lineages, namely Type I, II and III are prevalent worldwide. In mouse model, T. gondii strains can be divided into three groups based on their virulence, including the virulent (LD100=1), the intermediately virulent (LD50 = 103-104) and the non virulent (LD50 > 105). The clonal Type I, II and III T. gondii strains belong to these three groups, respectively. Epidemiologic studies suggest the …


Evaluation Of Chromosomally-Integrated Luxcdabe And Plasmid-Borne Gfp Markers For The Study Of Localization And Shedding Of Stec O91:H21 In Calves, Yingying Hong May 2011

Evaluation Of Chromosomally-Integrated Luxcdabe And Plasmid-Borne Gfp Markers For The Study Of Localization And Shedding Of Stec O91:H21 In Calves, Yingying Hong

Masters Theses

Shiga toxin-producing Escherichia coli (STEC) has been recognized as an important foodborne pathogen. Of this group, O91 is one of the common serogroups frequently isolated from patients and food in some countries, with O91:H21 being previously implicated in hemolytic uremic syndrome (HUS). Cattle are principle reservoirs for STEC, and studies examining STEC shedding in cattle often include experimental inoculation of strains of interest using antibiotic resistance markers for identifiable recovery. However, indigenous fecal microbes exhibiting similar resistance patterns can confound such studies. Such was the case in a study by our group when attempting to characterize shedding patterns of O91:H21 …


Study Of Population Diversity Of Toxoplasma Gondii, Debashree Majumdar Dec 2010

Study Of Population Diversity Of Toxoplasma Gondii, Debashree Majumdar

Masters Theses

Toxoplasma gondii, the causal agent of toxoplasmosis, is an important water and food borne protozoan parasite. T. gondii was previously shown to have a distinct clonal population structure composed of Type I, II and III lineages in North America and Europe. But more recent studies demonstrated high diversity in South America. In the present project we have conducted an intensive study of the population diversity of T. gondii and surveyed the extent of genetic variation among natural T. gondii isolates on a global scale in order to better understand the population dynamics and pathogenesis of this parasite. To this …


Methicillin Resistance In Staphylococcus Pseudintermedius, Chad Christopher Black Aug 2010

Methicillin Resistance In Staphylococcus Pseudintermedius, Chad Christopher Black

Doctoral Dissertations

Staphylococcus pseudintermedius affecting dogs is analogous to S. aureus on humans, acting as both normal flora and opportunistic pathogen. Methicillin resistance in S. pseudintermedius is recent, with the first documented occurrence of an isolate bearing the methicillin resistance gene, mecA, in 1999. This gene encodes penicillin binding protein 2a, which renders all beta-lactam drugs ineffective and functions as a “gateway” antibiotic resistance determinant. In the presence of ineffective antibiotics, opportunities for mutational events and acquisition of mobile genetic elements increase as microbial densities increase, often leading to multi-drug resistance. Methicillin-resistant S. pseudintermedius (MRSP) infections have become increasingly common. For …


Campylobacter Pathogenesis And Subunit Vaccine Development, Ximin Zeng Aug 2010

Campylobacter Pathogenesis And Subunit Vaccine Development, Ximin Zeng

Doctoral Dissertations

Campylobacter jejuni is the leading bacterial cause of human gastroenteritis in the United States. Increasing resistance of Campylobacter to clinical antibiotics raises an urgent need for novel strategies to prevent and control infections in humans and animal reservoirs, which necessitates a better understanding of Campylobacter pathogenesis. We hypothesize that multidrug efflux pump CmeABC and ferric enterobactin (FeEnt) iron acquisition systems, which play a critical role in Campylobacter pathogenesis, are novel targets for developing effective measures against Campylobacter. To test this, the molecular, antigenic, functional, and protective characteristics of two outer membrane proteins, CmeC (an essential component of CmeABC drug efflux …