Life Sciences Commons^™

Pathogenicity Of Acinetobacter Calcoaceticus, Kaitlan A. Sullivan

MUSC Theses and Dissertations

Acinetobacter is a genus of gram-negative bacteria that have been appearing frequently in hospitals contributing to infections in the blood, lungs, urinary tract, and other parts of the body. It infects patients with weakened immune systems that are placed on ventilators, after the use of catheters, or have any other open wounds produced by prolonged hospital stays. This genus of bacteria is problematic due to its high probability of becoming resistant to multiple classes of antibiotics. Thus, we are determining the pathogenicity of clinical isolates of Acinetobacter calcoaceticus using the organism Caenorhabditis elegans as a model.

We are testing …

Influenza C And D Viruses Demonstrated A Differential Respiratory Tissue Tropism In A Comparative Pathogenesis Study In Guinea Pigs, Chithra C. Sreenivasan, Runxia Liu, Rongyuan Gao, Yicheng Guo, Ben M. Hause, Milton Thomas, Ahsan Naveed, Travis Clement, Dana Rausch, Jane Christopher-Hennings, Eric Nelson, Julian Druce, Miaoyun Zhao, Radhey S. Kaushik, Qingsheng Li, Zizhang Sheng, Dan Dan, Feng Li

Nebraska Center for Virology: Faculty Publications

Influenza C virus (ICV) is increasingly associated with community-acquired pneumonia (CAP) in children and its disease severity is worse than the influenza B virus, but similar to influenza A virus associated CAP. Despite the ubiquitous infection landscape of ICV in humans, little is known about its replication and pathobiology in animals. The goal of this study was to understand the replication kinetics, tissue tropism, and pathogenesis of human ICV (huICV) in comparison to the swine influenza D virus (swIDV) in guinea pigs. Intranasal inoculation of both viruses did not cause clinical signs, however, the infected animals shed virus in nasal …

Impacts Of Bacterial Evolution On Host Lethality In Drosophila, Andrew Preston

College of Arts & Sciences Senior Honors Theses

Evolution is the process by which species change their genetic traits, such as the pathogenicity of bacteria, over time in response to changes in their environment. Although the genetic mechanisms underlying many evolutionary processes have been revealed, it is still not well understood how opportunistic pathogens, such as Pseudomonas aeruginosa, become virulent. The overall goal of this thesis is to test the Coincidental Evolution Hypothesis, which proposes that the virulence of opportunistic pathogens evolves coincidentally as a by-product of their interaction with their natural predators. I hypothesized that the virulence of ancestral Pseudomonas aeruginosa changes over time if it co-evolves …

Acinetobacter Baumannii - The Perfect Pathogen, Jesse Guzik, Myrna Rezcallah, Alexcia Zeller, Kaite Mattson

Research and Scholarship Symposium Posters

Acinetobacter was discovered in 1911 by Martinus Beijerinck. Acinetobacter baumannii didn't receive its scientific name until 1986. A. baumannii is now commonly referred to as "Iraqibacter" due to a rise in infections among US military personnel returning from Iraq and Afghanistan. After the Iraq War began in 2003, the frequency of cases began to rise, especially among patients in intensive care units. Patients using ventilators, catheters, have postoperative wounds, stay in the hospital for an extended period of time, or are immunocompromised are at a considerably higher risk of getting A. baumannii. Because of its large number of virulence …

The Antibacterial Efficacy Of Silver (I) Cyanoximates Against Streptococcus Mutans Ua159 Biofilm Growth And Infection In Galleria Mellonella Larvae, Jill Hughes

Honors Program Theses

Streptococcus mutans is the known etiological agent of dental caries. S. mutans’ virulence factors, namely biofilm formation and lactic acid fermentation, contribute to its pathogenic behavior within the oral cavity. Biofilms are thick, antibiotically resistant communities of bacteria that are much more difficult to treat than planktonic or free-floating bacteria. Continued misuse of antibiotics against dynamic communities, like biofilms, has led to increased research on non-antibiotic alternatives. Amongst these alternatives, there are silver and silver-based compounds. Silver is commonly incorporated into medicine due to its inhibitory and bactericidal effects and antibacterial properties. Silver (I) cyanoximates have demonstrated promising antibacterial activity …

The Identification Of Two M20b Family Peptidases Required For Full Virulence In Staphylococcus Aureus, Nathanial James Torres, Devon Rizzo, Maria A. Reinberg, Mary-Elizabeth Jobson, Brendan C. Totzke, Jessica K. Jackson, Wenqi Yu, Lindsey Neil Shaw

Molecular Biosciences Faculty Publications

We have previously demonstrated that deletion of an intracellular leucine aminopeptidase results in attenuated virulence of S. aureus. Herein we explore the role of 10 other aminopeptidases in S. aureus pathogenesis. Using a human blood survival assay we identified mutations in two enzymes from the M20B family (PepT1 and PepT2) as having markedly decreased survival compared to the parent. We further reveal that pepT1, pepT2 and pepT1/2 mutant strains are impaired in their ability to resist phagocytosis by, and engender survival within, human macrophages. Using a co-infection model of murine sepsis, we demonstrate impairment of dissemination and survival …

Distribution Patterns Of Allorhizobium Vitis In Missouri Vineyards And Non-Vineyard Soils, Jacquelyn M. Wray

MSU Graduate Theses

Crown gall disease causes significant economic loss to the grape and wine industry. Preventive strategies are most effective for mitigating the loss of grapevines in vineyards, as there is no known cure for this disease. The bacterium Allorhizobium vitis carrying a tumor-inducing (Ti) plasmid is the causative agent. A. vitis bacteria live systemically in the grapevine before causing visible symptoms and can survive in residual plant tissues and soil for more than two years. Diagnostic methods have been developed to detect A. vitis bacteria in grapevines and soil. However, more reliable, specific, and high-throughput diagnostics are still needed for screening …

Resolving The Repression Pathway Of Virulence Gene Hila In Salmonella, Alexandra King, Lon Chubiz Phd, Brenda Pratte, Lauren Daugherty

Undergraduate Research Symposium

Salmonella is a relatively abundant, virulent species of bacteria that is most known for spreading gastrointestinal diseases through food. These illnesses result in approximately 1.35 million infections, including over 25,000 hospitalizations each year, in the U.S. alone (CDC.gov). As antibiotic resistance becomes an increasingly urgent public health problem, the importance of developing alternative treatment methods is only becoming more crucial. One of the genes responsible for this virulence is known as hilA. HilA is the main transcriptional regulator of Salmonella Pathogenicity Island-1 gene (UniProt). SPI-1 plays an important role in the invasion of Salmonella into epithelial cells. The proteins encoded …

Mara Repression Of Virulence Gene Hila In Salmonella, Alexandra King, Lauren Daugherty, Lon Chubiz Phd

Undergraduate Research Symposium

Salmonella is a bacteria most commonly known for causing the eponymous food-related illness. Due to their rapid reproduction rate and their ability to be propogated and maintained in a lab setting, they are commonly used in lab studies so that we can better understand how Salmonella causes disease in organisms that are more difficult to study. One area of interest is analyzing how Salmonella controls expression of the mechanisms that actually cause disease, called virulence traits, in response to the environment. In this study, antibiotic stress was used to analyze virulence gene expression. MarA is a gene that regulates ampicillin …

Roles Of Secreted Proteins And Iron Utilization Proteins In Virulence Of The Fish Pathogen Flavobacterium Columnare, Rachel Conrad

Theses and Dissertations

The Gram-negative bacterium Flavobacterium columnare is the causative agent of columnaris disease and is responsible for significant economic losses in aquaculture. Little is known regarding the virulence factors produced by F. columnare, and control measures are limited. Like many members of the phylum Bacteroidetes, F. columnare uses the type IX secretion system (T9SS) to secrete enzymes, adhesins, and proteins involved in gliding motility. When a core component of this system was deleted in the wild type strain, the resulting mutant was avirulent in zebrafish, rainbow trout, and channel catfish infection studies. This suggests that the individual secreted proteins may function …

Increasing The Frequency Of Periodic Spatial Disturbance Decreases Surface Attachment Protein Expression In Staphylococcus Aureus, Ivana M. Barraza

All HCAS Student Capstones, Theses, and Dissertations

Staphylococcus aureus is an opportunistic pathogen that can cause a variety of acute and chronic illnesses. The severity of these illnesses such as sepsis, necrotizing pneumonia, and toxic shock syndrome is measured through the virulence that S. aureus inflicts on its host. Methicillin-resistant S. aureus (MRSA) is commonly associated with secondary infections and is challenging to treat given the limited selection of antibiotics that are effective against it. Accordingly, novel approaches to reduce S. aureus pathogenicity are required. S. aureus regulates pathogenesis through a cell-to-cell communication system referred to as quorum sensing. Effective communication determines the production of two broad …

Molecular Mechanisms Of Antimicrobial Resistance In Multi-Drug Resistant Enterococci, Ayesha Khan

Dissertations & Theses (Open Access)

Antibiotic resistance is a major global public health threat. Enterococci are recalcitrant, nosocomial pathogens that can be intrinsically resistant to valuable antibiotics, like beta-lactams, or evolve resistance to all existing antimicrobials. The LiaFSR system regulates resistance to cell membrane (CM) stressors like daptomycin (DAP), a front-line drug for multi-drug resistant infections. DAP resistance (DAP-R) in E. faecalis is mediated by CM phospholipid alterations. Emergence of DAP-R often leads to b-lactam resensitization, a phenomenon called the seesaw effect. The molecular mechanism of DAP-R and the seesaw effect are unknown. Here we show that LiaX is a surface exposed protein whose C-terminal …

Genome Sequencing Analysis Of Laboratory Isolate Of Francisella Noatunensis Subs. Orientalis, Joseph Paquette

Senior Honors Projects

Francisella noatunensis subs. orientalis is a known fish pathogen that has been most notably isolated from tilapia (Oreochromis niloticus) in Costa Rica. The genome of this Francisella species pathogen has been sequenced using Next-Generation Sequencing and been made available for the scientific community. Dr. Kathryn Ramsey’s research laboratory in the Department of Cell and Molecular Biology at the University of Rhode Island works with several Francisella species pathogens and is interested in identifying the differences, if any, between the known genome sequence of Francisella noatunensis and that of a laboratory isolate of the same species. With the use …

Characterization Of The Putative Polysaccharide Synthase Cpsa And Its Effects On The Virulence Of The Human Pathogen Aspergillus Fumigatus, Binita Nepal

Graduate Research Theses & Dissertations

The fungus Aspergillus fumigatus is a ubiquitous opportunistic human pathogen capable of causing a life-threatening disease called invasive aspergillosis, or IA, with an associated 40–90% mortality rate in immunocompromised patients. Of the approximately 250 species known in the genus Aspergillus, A. fumigatus is responsible for up to 90% of IA infections. This study focuses on examining the role of the putative polysaccharide synthase cpsA gene in A. fumigatus virulence. Additionally, we evaluated its role in cellular processes that influence invasion and colonization of host tissue. Importantly, our results support that cpsA is indispensable for virulence in A. fumigatus infection of …

Transposon Mutagenesis Facilitates Discovery Of Genotype-Phenotype Associations And Functional Interrogation Of The Mycobacterium Kansasii Genome, William C. Budell

Dissertations, Theses, and Capstone Projects

Mycobacterium kansasii (Mk) is a nontuberculous mycobacterium (NTM) and medically relevant opportunistic human pathogen. Mk causes dangerous disease pathologies ranging from tuberculosis-like chronic pulmonary disease (CPD) to non-pulmonary focal or disseminated infections that are exacerbated by comorbidities such as chronic obstructive pulmonary disease (COPD), co-infection with HIV, or cancer. Among the most frequently identified cause of NTM-linked CPD, Mk infections contribute to a globally increasing NTM disease burden and are difficult to treat, requiring a long-term, multi-drug regimen. Although a less virulent pathogen than Mycobacterium tuberculosis (Mtb), Mk elicits similar disease features and shares in vitro …

Characterization Of The Role Of Transcriptional Regulator Of Arac/Xyls Family In Tularemia Pathogenesis, Dina Marghani

NYMC Student Theses and Dissertations

The Tier 1 Select Agent, Francisella tularensis causes an acute and fatal disease known as tularemia. Many studies have devoted enormous efforts to understand how F. tularensis avoids host defense mechanisms, replicates within an extremely secure immune system, and eventually causes the deadly disease tularemia. The extremely high virulence of Francisella depends on its ability to manipulate gene expression according to the surrounding environment. This process requires the involvement of unique transcriptional regulators. Francisella possesses very few transcriptional regulators, and a majority of them characterized to-date have been shown to regulate genes involved in virulence and cellular functions. The role …

Study Of Genetic Regulators That Control Development And Secondary Metabolism In The Genus Aspergillus, Timothy Satterlee

Graduate Research Theses & Dissertations

In this study, I investigated the role of two different regulatory genes in two different species of pathogenic fungi from the genus Aspergillus. The first study involves a transcriptome analysis of the epigenetic regulator rmtA in the plant pathogen Aspergillus flavus. A. flavus colonizes numerous oil seed crops such as corn, peanuts, treenuts and cotton worldwide, contaminating them with aflatoxins and other harmful potent toxins. Previously our lab characterized the gene rmtA, which encodes an arginine methyltransferase in A. flavus, and demonstrated its role as regulator of the expression of the aflatoxin gene cluster and concomitant synthesis of toxin. Furthermore, …

Oxygen Deprivation Influences The Survival Of Listeria Monocytogenes In Gerbils, Jillian Harris, Oindrila Paul, Si Hong Park, Sally White, Khemraj Budachetri, Daniel M. Mcclung, Jessica G. Wilson, Alicia K. Olivier, Justin A. Thornton, Paul R. Broadway, Steven C. Ricke, Janet R. Donaldson

Faculty Publications

Listeria monocytogenes is a facultative anaerobic foodborne pathogen capable of surviving harsh environments. Recent work has indicated that anaerobic conditions increase the resistance capability of certain strains to environmental stressors. The goal of the study was to conduct a preliminary study to determine whether exposure to anaerobic conditions prior to infection increases the ability to survive in vivo. Gerbils were inoculated with one of five doses of the L. monocytogenes strain F2365 by oral gavage: phosphate-buffered saline (control), 5 × 10⁶ colony forming units aerobic culture (low aerobic), 5 × 10⁸ aerobic culture (high aerobic), 5 × 10 …

Transcriptional Silencing And Anti-Silencing Of Virulence Genes In The Bacterial Pathogen Shigella Flexneri: Virb, Dna Supercoiling, And The Histone-Like Nucleoid Structuring Protein, Michael Adam Picker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Transcriptional silencing and anti-silencing affect many aspects of bacterial physiology, including virulence in bacterial pathogens. In Shigella species, a group of gram-negative pathogens that cause bacillary dysentery in humans, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences virulence genes found on the large virulence plasmid while VirB anti-silences these genes. However, the mechanistic details of their interplay are not fully understood. To elucidate their regulatory mechanisms, I use the icsP virulence locus, which shares a long intergenic region with the divergently transcribed ospZ gene (1535 bp from TSS to TSS). Prior to this work, two discrete H-NS binding regions had …

The Characterization Of The Transcription Factor Msab And Its Role In Staphylococcal Virulence, Justin Batte

Dissertations

Staphylococcus aureus is a common human pathogen that is responsible for a wide range of infections, ranging from relative minor skin infections to life-threatening disease such as bacteremia, septicemia, and endocarditis. S. aureus possesses many different virulent factors that aid in its ability to cause this wide array of infections. One major virulence factor includes the production of capsular polysaccharide (CP). The production of CP plays a major role in the virulence response during infection specifically by providing S. aureus an antiphagocytic mechanism that allows the pathogen to evade phagocytosis during an infection. S. aureus has developed complex genetic regulatory …

Functional Similarity Of Prd-Containing Virulence Regulators In Bacillus Anthracis, Malik Raynor

Dissertations & Theses (Open Access)

Bacillus anthracis produces three regulators, AtxA, AcpA, and AcpB, that control virulence gene expression and are members of an emerging class of regulators termed “PCVRs” (Phosphoenolpyruvate-dependent phosphotransferase regulation Domain-Containing Virulence Regulators). AtxA controls expression of the toxin genes; lef, cya, and pag, and is the master virulence regulator and archetype PCVR. AcpA and AcpB are less well studied. AcpA and AcpB independently positively control transcription of the capsule biosynthetic operon capBCADE, and culture conditions that enhance AtxA activity result in capBCADE transcription in strains lacking acpA and acpB. RNA-Seq was used to assess the regulons of the …

Nutritional Virulence Of Legionella Pneumophila., Ashley M. Best

Electronic Theses and Dissertations

Legionella pneumophila is an environment organism that parasitizes a wide range of protozoa. Growth within the environmental host primes L. pneumophila for infection of human alveolar macrophages when contaminated aerosols are inhaled. Intracellular replication within either host requires the establishment a replicative niche, known as the Legionella-containing vacuole (LCV). Biogenesis of the LCV depends on the type IVb translocation system, the Dot/Icm, to translocation >320 effectors into the host cytosol. Effectors are responsible for preventing lysosome fusion to the LCV, recruitment of ER-derived vesicles to the LCV, and modulation of a plethora of host processes to promote the intracellular …

Characterizing The Virulence Factor Yape In Yersinia Pestis., Tiva Templeton Vancleave

Electronic Theses and Dissertations

Yersinia pestis is the causative agent of bubonic plague and is primarily transmitted by fleas. Upon infection, the bacteria rapidly travel to the regional lymph nodes causing inflammation and cellulitis in these tissues (referred to as buboes). Two outer membrane proteins, YapE and Pla, have been implicated to have roles in dissemination to the lymph nodes. Their adhesive properties have shown that they are able to interact with host macrophages thereby increasing their ability to disseminate to regional lymph nodes. More recently, we have shown that YapE is cleaved by another virulence factor important for lymph node colonization, Pla, to …

Determining If Host Serum Igg Titer Is Associated With Toxoplasma Gondii Virulence, Riley E Byrd

Chancellor’s Honors Program Projects

No abstract provided.

A Comparison Of Oral And Intravenous Mouse Models Of Listeriosis, Michelle G. Pitts, Sarah E. F. D'Orazio

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Listeria monocytogenes is one of several enteric microbes that is acquired orally, invades the gastric mucosa, and then disseminates to peripheral tissues to cause systemic disease in humans. Intravenous (i.v.) inoculation of mice with L. monocytogenes has been the most widely-used small animal model of listeriosis over the past few decades. The infection is highly reproducible and has been invaluable in deciphering mechanisms of adaptive immunity in vivo, particularly CD8+ T cell responses to intracellular pathogens. However, the i.v. model completely bypasses the gut phase of the infection. Recent advances in generating both humanized mice and murinized bacteria, as well …

Characterization Of Two Cyclic Di-Gmp Phosphodiesterases Hypothesized To Regulate Virulence In Streptomyces Scabies, Madison Flasco

Undergraduate Honors Thesis Projects

Common scab is a devastating disease that affects the marketability of potatoes. The disease results in raised and pitted lesions seen on the surface of the potato and is caused by the soil pathogen, Streptomyces scabies. The S. scabies genome has two cyclic-di-GMP phosphodiesterases, RmdA and RmdB, both regulators of morphology and development. These proteins break down the ubiquitous second messenger molecule cyclic di-GMP, a molecule in charge of cell cycle progression and virulence. Both proteins contain diguanylate cyclase domains and phosphodiesterase domains, GGDEF and EAL, respectively, while RmdA contains an additional PAS_4 domain. Despite similar domain configurations, the two …

Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone

Graduate Theses and Dissertations

Foodborne illnesses are a leading cause of infectious diseases in the world. Among enteric organisms Salmonella is a key pathogen. It’s high prevalence in poultry and other food-animal sources make it imperative to study. Salmonella has the ability to modify its genetic content with help of mobile genetic elements such as plasmids. Incompatibiltiy group 1 (IncI1) plasmids are commonly reported in Salmonella. This study evaluates role on IncI1 plasmids in antimicrobial resistance and virulence in Salmonella. Genetic determinants of resistance and virulence are noted among our IncI1-containing Salmonella isolates. These genetic elements are also transferable and reported to carry respective …

The Algz/R Two-Component System Is Responsible For Attenuation Of Virulence In Pseudomonas Aeruginosa, Danielle A. Williams

Electronic Theses and Dissertations

Pseudomonas aeruginosa is an important opportunistic pathogen. Many P. aeruginosa virulence factors are regulated by the AlgZ/R two component system. AlgZ is the sensor histidine kinase which phosphorylates AlgR, the response regulator. AlgR activates transcription of different gene targets based upon its phosphorylation state. The genes that encode AlgZ and AlgR are transcribed in an operon. While regulation of algR expression has been well studied, regulation of algZ expression has not. Using a pilW mutant in concert with algZTF-lacZ transcriptional fusion, we conducted a transposon mutagenesis to identify algZ regulators. We identified an unknown autoregulatory loop. The type …

Examination Of Bcaa Transport And Synthesis In Staphylococcus Aureus, Julienne Kaiser

Electronic Thesis and Dissertation Repository

Staphylococcus aureus is a human pathogen capable of causing infections that range from mild skin and soft tissue infections to severe infections of the bone, muscle, heart, and lung. To survive and thrive in such diverse host environments, S. aureus must maintain sufficient levels of metabolites and cofactors to support virulence determinant production and replication. The branched-chain amino acids (BCAAs; Ile, Leu, Val) represent an important group of nutrients for S. aureus metabolism, as they are required for protein synthesis and synthesis of membrane branched-chain fatty acids (BCFAs), which are important for S. aureus environmental adaptation. Moreover, the BCAAs are …

The Regulatory Relationship Of Transcriptional Regulators Msab And Cody In Capsule Production In Staphylococcus Aureus, Brittany L. Trunell

Honors Theses

There are many transcriptional regulators found in pathogenic Staphylococcus aureus. Many of these regulators are essential for the organism’s ability to switch from commensal form to the virulent pathogenic form. One of these main regulators is CodY. This regulator has been shown to be responsive to nutrient availability during phases of growth. Additionally, we have recently found that MsaB, the only protein coding ORF of the msaABCR operon, is a putative co-regulator of capsule along with CodY. To explore these regulator interactions, we produced mutations of codY and msaABCR individually and a double mutation of msaABCR/ codY. We have observed …