Microbiology Commons^™

Characterization Of Induced Rnai Silencing Of Vaccinia Virus Essential Genes, Kewa Jiang

Honors Scholar Theses

Vaccinia virus (VACV) is a large double-stranded DNA virus and the prototypical member of the family Poxviridae and is most notable for its use as the vaccine that eradicated smallpox (variola virus). More recently, VACV has been used to develop recombinant vaccines and immunotherapies. However, many of these processes require VACV replication to be tightly controlled. RNA interference (RNAi) is a powerful tool for in vitro silencing of mRNAs that are complementary to 19-21 base pairs (bp) of double-stranded RNA (dsRNA). This project outlines the design and preliminary analysis of two inducible RNAi silencing constructs targeting multiple VACV essential genes …

Sa-4-1bbl As A Modulator Of Innate, Adaptive, And Regulatory Immunity : Implications For Cancer Prevention And Treatment., Hampartsoum Barsoumian

Electronic Theses and Dissertations

SA-4-1BBL is a recombinant costimulatory molecule that is active in its soluble form and has pleiotropic effects on the functions of innate, adaptive, and regulatory immune cells. We have previously shown that SA-4-1BBL makes CD4+ T conventional cells (Tconvs) resistant to suppression by CD4+CD25+Foxp3+ T regulatory cells (Tregs). The mechanistic basis of this observation is the subject of this study. We demonstrate that Tconvs, but not Tregs, are the direct targets of SA-4-1BBL-mediated evasion of Treg suppression without contribution from antigen presenting cells (APCs). SA-4-1BBL engagement with its receptor, 4-1BB, on Tconvs resulted in the production of high levels of …

Effects Of Lactobacillus Rhamnosus Milk Isolate On The Production Of Inflammatory Cytokines In Enterocytes, Beverly C. Ngeny

Electronic Theses and Dissertations

In the gastrointestinal tract, probiotics have been shown to promote host immunity and to regulate immune signaling pathways. This study used Caco-2 cell line to examine the effects of a Lactobacillus rhamnosus isolate from “amabere amaruranu” a Kenyan traditional cultured milk, on the production inflammatory cytokines in enterocytes. Live Lactobacillus rhamnosus (MRS6AN), its cytoplasmic fraction (CF), filtered spent broth (FSB) or heat inactivated FSB (HIB) were used as treatments on differentiated Caco-2 cell monolayer in transwells. Cytokine content in the cell lysates, apical and basolateral supernatants were determined using ELISA. Caco-2 cell lysate treatments showed significantly increased anti-inflammatory TGF-β (ng/ml) …

Comparison Of Anti-Pneumococcal Functions Of Native And Modified Forms Of C-Reactive Protein, Donald Neba Ngwa

Electronic Theses and Dissertations

The anti-pneumococcal function of native C-reactive protein (CRP) involves its binding to phosphocholine molecules present on Streptococcus pneumoniae and subsequent activation of the complement system. However, when pneumococci recruit complement inhibitory protein factor H on their surface, they escape complement attack. Non-native forms of CRP have been shown to bind immobilized factor H. Accordingly, we hypothesized that modified CRP would bind to factor H on pneumococci, masking its complement inhibitory activity, allowing native CRP to exert its anti-pneumococcal function. As reported previously, native CRP protected mice from lethal pneumococcal infection when injected 30 minutes before infection but not when injected …

Effects Of Thermosonication On Microbial Population Reduction And Solubility Index In Skim Milk Powder, Nicola F. Beatty

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Thermosonication has been researched as a means to improve shelf life, quality, and functional properties in dairy products. This study explored the effects of thermosonication on the inactivation of Geobacillus stearothermophilus in concentrated skim milk as a function of total solids content, temperature, and time and investigated changes in the solubility of the skim milk. Results showed thermosonication had an increased bactericidal effect on both vegetative cells and spores as compared to heat treatment alone without affecting solubility. A model was developed using response surface analysis showing that log reductions produced by thermosonication can be predicted based on a polynomial …

Identification Of Host Factors Required For Yersinia Pestis Macrophage Intracellular Survival And Their Impact On Vacuole Maturation, Acidification And Trafficking., Michael Graylin Connor

Electronic Theses and Dissertations

Y. pestis is a facultative intracellular pathogen and the causative agent of plague. This bacterium, while most noted or the Black Death during the European 14^th century, is not a historic pathogen but a re-emerging pandemic with both domestic and global impact. Y. pestis is capable of colonizing the macrophage, and actively subverts phagolysosome maturation to establish a replicative niche known as the Yersinia containing vacuole (YCV). The exploited host factors required to support the YCV are unknown. Here we identified a comprehensive list of host factors required for Y. pestis survival through a genome-wide RNAi high-throughput screen. We …

Characterization Of The Role Of The Burkholderia Pseudomallei Type 3 Secretion System Using In Vivo Imaging., Maria Gabriela Gutierrez

Electronic Theses and Dissertations

Melioidosis is a fatal infectious disease caused by the Tier 1 Select Agent Burkholderia pseudomallei. Hallmarks of melioidosis include pneumonic disease and prominent septicaemic spread. Both forms of disease are contingent upon the bacterium’s intracellular life cycle and particularly on its ability to escape from host cell phagosomes. Upon encountering a host cell, B. pseudomallei is internalized into membrane-bound vacuoles from which the bacterium must rapidly escape to the cytoplasm in order to replicate and promote its survival. In the host cytoplasm, B. pseudomallei is capable of polymerizing actin for intracellular and intercellular motility and spread, lysing the host …

Modulation Of Cell Death Signaling And Cell Proliferation By The Interaction Of Homoserine Lactones And Paraoxonase 2., Aaron Mackallan Neely

Electronic Theses and Dissertations

Pseudomonas aeruginosa produces N-(3-oxododecanoyl)-homoserine lactone (C12) as a quorum-sensing molecule that functions to facilitate bacteria-bacteria communication. C12 has also been reported to affect many aspects of human host cell physiology, including evoking cell death in various types of cells. However, the signaling pathway(s) leading to C12-triggerred cell death remains unclear. To clarify cell death signaling induced by C12, we examined mouse embryonic fibroblasts (MEFs) deficient in one or more caspases. Our data indicate that, unlike most apoptotic inducers, C12 evokes a novel form of apoptosis in cells, probably through the direct induction of mitochondrial membrane permeabilization. Previous studies indicate that …

Insights Into Determinants That Contribute To Colonization, Virulence And Antibiotic Resistance In Enterococci, Maria Camila Montealegre

Dissertations and Theses (Open Access)

Enterococcus faecalis and Enterococcus faecium are increasingly common as causative agents of human infections, many of which are very difficult to treat due to multi-drug resistance. The work presented in the first part of this dissertation elucidates a mechanism for the regulation of pilus expression. I showed that ATT is the initiation codon of ebpA, the first gene of an operon that codes for the endocarditis and biofilm-associated pili (Ebp), a recognized virulence factor in E. faecalis. The presence of this rare start codon downregulates EbpA translation and protein levels, diminishing biofilm and binding abilities of …

The Thioredoxin Trx-1 Regulates The Major Oxidative Stress Response Transcription Factor, Skn-1, In Caenorhabditis Elegans, Katie C. Mccallum

Dissertations and Theses (Open Access)

The ability to respond to hostile environmental conditions is critical for the survival of an organism. Oxidative stress is an adverse state in which reactive oxygen species (ROS) accumulate to a harmful level and, if left unresolved, can lead to cellular dysfunction and organismal disease. Sophisticated detoxification systems, characterized by a battery of enzymatic antioxidants, are utilized to neutralize ROS thereby reducing stress. However, ROS are also purposefully produced by designated cellular enzymes to facilitate the signaling and regulation of critical physiological processes. Therefore, both the production and neutralization of ROS must be tightly controlled. Indeed, the expression of detoxification …

Organization And Regulation Of Proteins Required For Initiation Of Cell Division In Escherichia Coli, Veronica W. Rowlett

Dissertations and Theses (Open Access)

The process of bacterial cell division relies on the assembly of multiple proteins to form the cell division machine, or “divisome.” FtsZ, a bacterial homolog of eukaryotic tubulin, forms a ring-like structure, the “Z ring,” at midcell and serves as a scaffold for divisome assembly and potential force generator during synthesis of the division septum. Both FtsA, a bacterial homolog of eukaryotic actin, and ZipA, a single-pass transmembrane protein, anchor the Z ring to the inner membrane, are required for the localization of other divisome proteins to midcell, and likely influence the assembly state of FtsZ. Positioning of the Z …

Characterization Of The Ato Gene Family In Alternative Carbon Metabolism, Heather A. Danhof

Dissertations and Theses (Open Access)

As a commensal colonizer and opportunistic pathogen, Candida albicans is the most clinically important human associated fungus. Systemic infection carries an unacceptably high mortality rate of ~40% in the growing population of immunocompromised individuals. Macrophages are important innate immune cells that limit the niches in the human body in which C. albicans can persist through phagocytic removal. However, following phagocytosis C. albicans readily escapes from the immune cell by differentiating into filamentous hyphae, a process that should be inhibited in the normally acidic phagolysosome. We have shown that C. albicans induces germination by neutralizing the phagolysosome. To better understand this …

Global Worming: A Quantitative Study About Greenhouse Gas Flux In Surface Soils Facilitated By The Anecic Earthworm, Lumbricus Terrestris, Under Rising Global Temperature, Rachel Briden Frei, Jose A. Amador

Senior Honors Projects

Climate change is the long-term alteration in the Earth’s average weather conditions believed to be driven by greenhouse gases (GHG): carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). These alterations are expected to cause more extreme weather events, gradually warmer global temperatures and greater amounts of precipitation. Roughly 20% of the Earth’s CO₂, one-third of CH₄ and two-thirds of N₂O emissions, originate from soils, and earthworms are known to accelerate GHG. As climate change proceeds, there is expected to be an increase in global temperature of 2-6ºC. Temperature …

The Path To Understanding Salt Tolerance: Global Profiling Of Genes Using Transcriptomics Of The Halophyte Suaeda Fruticosa, Joann Diray Arce

Theses and Dissertations

Salinity is a major abiotic stress in plants that causes significant reductions in crop yield. The need for improvement of food production has driven research to understand factors underlying plant responses to salt and mechanisms of salt tolerance. The aim of improving tolerance in traditional crops has been initiated but most crops can only tolerate a limited amount of salt in their systems to survive and produce biomass. Studies of naturally occurring high salt-tolerant plants (halophytes) are now being promoted for economic interests such as food, fodder or ecological reasons. Suaeda fruticosa, a member of the family Chenopodiaceae, belongs …

Effectiveness Of Commercially-Available Cosmetic Cleaners On Cosmetics And Cosmetic Brushes, Vanessa Ortiz

UNLV Theses, Dissertations, Professional Papers, and Capstones

The complex nature of skin contributes to the microbial population present on its surface. While normal skin flora is either beneficial or has no effect on the body, there are instances where pathogenic microorganisms are present and can cause infections. Damaged skin is more susceptible to infections from these microbes. Behavioral characteristics, such as the use of cosmetics, can affect the microbial population present on the skin. Staphylococcus aureus is the organism most commonly isolated from cosmetics, and it can be responsible for conjunctivitis, impetigo, boils, and folliculitis.

There are many ways microbial contamination of cosmetics can occur, such as …

Microbial Contamination Of Ice At Food Establishments In Las Vegas, Nevada, Jerry Wills

UNLV Theses, Dissertations, Professional Papers, and Capstones

When food establishments make ice for consumption, it is important to use water free of pathogens and to employ hygienic practices. Freezing can reduce the number of culturable microorganisms present in water but does not eliminate them completely. Coliform bacteria are used as an indicator of water quality and are used to test for fecal contamination. The U.S. Environmental Protection Agency (EPA) establishes standards for drinking water, and has set a goal for zero total coliforms. Another commonly used tool to measure water quality is the heterotrophic plate count (HPC). The EPA limit for HPC is 500 colony forming units …

The Ccaat-Binding Factor Dependent Regulation Of The Oxidative Stress Response In Candida Albicans, Ananya Chakravarti

Graduate Theses and Dissertations

The success of Candida albicans as an opportunistic human pathogen has been attributed to several factors, including the ability to survive in limiting iron environments and the ability to evade the respiratory burst of human macrophages and neutrophils. The goal of this research is to elucidate the role of the CCAAT-binding factor in the oxidative stress response of Candida albicans. Prior whole genome microarray studies performed in our lab compared the gene expression of a wild type Candida albicans strain versus a hap5Δ strain under iron-limiting growth conditions. Among the differentially regulated genes, CTA1, encoding catalase, had a four-fold higher …

Isolation Frequency And Susceptibility Pattern Of Non-O1 And Non-O139 Vibrio Cholerae In A Tertiary Health Care Laboratory, 1999-2012, S Irfan, N Fasih, N K. Ghanchi, Erum Khan

Department of Pathology and Laboratory Medicine

In the past decade the importance of non-O1 and non-O139 strains of Vibrio cholerae has been highlighted globally. This study aimed to evaluate the frequency and antimicrobial susceptibility profile of non-O1 and non-O139 V. cholerae in Pakistan. Data of stool specimens yielding growth of non-O1 and non-O139 V. cholerae isolated at a national referral laboratory from 1999 to 2012 were retrospectively analysed and evaluated for resistance to ampicillin, tetracycline, chloramphenicol, co-trimoxazole and ofloxacin. A total of 95 800 stool samples submitted over 1999-2012 yielded 3668 strains of V. cholerae, of which 6% were non-O1 and non-O139 V. cholerae. A high …

Alternative Pathway For Provision Of Acyl Coa Precursors For Fatty Acid Biosynthesis: Purification And Kinetic Characterization Of Phosphotransbutyrylase And Butyrate Kinase From Listeria Monocytogenes, Sirisha Sirobhushanam

Theses and Dissertations

Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a disease characterized by gastroenteritis, meningitis, spontaneous miscarriages and high mortality rate among infected individuals. L. monocytogenes is a major concern in the food industry, due to its ability to grow at refrigeration temperatures and the zero tolerance policy of the FDA, resulting in expensive food recalls. Growth at low temperatures is aided in part by the high membrane content of branched-chain fatty acids (BCFAs) which imparts greater fluidity to the membrane. Mutants of L. monocytogenes impaired in BCFA biosynthesis display diminished growth at normal and low temperatures, exhibit lower tolerance …

Development Of A Non-Invasive Liquid Biopsy For Detection Of Cmvil-10, Alexander Shin, Margarette Mariano, Juliet Spencer

Creative Activity and Research Day - CARD

Human cytomegalovirus (HCMV) is a prevalent type of herpes virus in our population. HCMV infection has no effect on the majority of people, but in some cases HCMV is strongly correlated with various medical outcomes, such as breast cancer. We focus on the UL111A gene product of HCMV, which encodes the secreted protein cmvIL-10. CmvIL-10 is a homolog of human cytokine IL-10 (hIL-10), which has immunosuppressive effects and promotes proliferation and invasion of breast cancer cells in vitro. We are measuring cmvIL-10 in human blood and have found elevated levels of cmvIL-10 in cancer patients. Here, we are investigating the …