Medical Microbiology Commons^™

Biliary Microbiota, Gallstone Disease And Infection With Opisthorchis Felineus., Irina V. Saltykova, Vjacheslav A Petrov, Maria D Logacheva, Polina G Ivanova, Nikolay V Merzlikin, Alexey E Sazonov, Ludmila M Ogorodova, Paul J. Brindley

Microbiology, Immunology, and Tropical Medicine Faculty Publications

BACKGROUND: There is increasing interest in the microbiome of the hepatobiliary system. This study investigated the influence of infection with the fish-borne liver fluke, Opisthorchis felineus on the biliary microbiome of residents of the Tomsk region of western Siberia.

METHODOLOGY/PRINCIPAL FINDINGS: Samples of bile were provided by 56 study participants, half of who were infected with O. felineus, and all of who were diagnosed with gallstone disease. The microbiota of the bile was investigated using high throughput, Illumina-based sequencing targeting the prokaryotic 16S rRNA gene. About 2,797, discrete phylotypes of prokaryotes were detected. At the level of phylum, bile from …

Type Iv Pili Promote Early Biofilm Formation By Clostridium Difficile, Grace A. Maldarelli, Kurt H. Piepenbrink, Alison J. Scott, Jeffrey A. Freiberg, Yang Song, Yvonee Achermann, Robert K. Ernst, Mark E. Shirtliff, Eric J. Sundberg, Michael S. Donnenberg, Erik C. Von Rosenvinge

Food for Health: Publications

Increasing morbidity and mortality from Clostridium difficile infection (CDI) present an enormous challenge to healthcare systems. Clostridium difficile express type IV pili (T4P), but their function remains unclear. Many chronic and recurrent bacterial infections result from biofilms, surface-associated bacterial communities embedded in an extracellular matrix. CDI may be biofilm mediated; T4P are important for biofilm formation in a number of organisms. We evaluate the role of T4P in C. difficile biofilm formation using RNA sequencing, mutagenesis and complementation of the gene encoding the major pilin pilA1, and microscopy. RNA sequencing demonstrates that, in comparison to other growth phenotypes, C. difficile …

A Cell Cycle-Regulated Toxoplasma Deubiquitinase, Tgotud3a, Targets Polyubiquitins With Specific Lysine Linkages, Animesh Dhara, Anthony P. Sinai

Microbiology, Immunology, and Molecular Genetics Faculty Publications

The contribution of ubiquitin-mediated mechanisms in the regulation of the Toxoplasma gondii cell cycle has remained largely unexplored. Here, we describe the functional characterization of a T. gondii deubiquitinase (TGGT1_258780) of the ovarian-tumor domain-containing (OTU) family, which, based on its structural homology to the human OTUD3 clade, has been designated TgOTUD3A. The TgOTUD3A protein is expressed in a cell cycle-dependent manner mimicking its mRNA expression, indicating that it is regulated primarily at the transcriptional level. TgOTUD3A, which was found in the cytoplasm at low levels in G₁ parasites, increased in abundance with the progression of the …

Microrna Mir-155 Is Necessary For Efficient Gammaherpesvirus Reactivation From Latency, But Not For Establishment Of Latency, Rebecca L. Crepeau, Peisheng Zhang, Edward J. Usherwood

Dartmouth Scholarship

MicroRNA-155 (miR-155) has been shown to play significant roles in the immune response, including in the formation of germinal centers (GC) and the development and maturation of T follicular helper (Tfh) cells. There is in vitro evidence to support a critical role for cellular miR-155 and viral miR-155 homologs in the establishment of gammaherpesvirus latency in B cells. We sought to determine the contribution of miR-155 to the establishment and maintenance of latency in vivousing murine gammaherpesvirus (MHV-68) infection. MHV-68-infected mice deficient in miR-155 exhibited decreases in GC B cells and Tfh cells. However, the frequencies of spleen cells …

Cyclic Di-Gmp-Regulated Periplasmic Proteolysis Of A Pseudomonas Aeruginosa Type Vb Secretion System Substrate, Richard B. Cooley, T. Jarrod Smith, Wilfred Leung, Valerie Tierney, Bradley Borlee, George A. O'Toole, Holger Sondermann

Dartmouth Scholarship

We previously identified a second-messenger-regulated signaling system in the environmental bacterium Pseudomonas fluorescens which controls biofilm formation in response to levels of environmental inorganic phosphate. This system contains the transmembrane cyclic di-GMP (c-di-GMP) receptor LapD and the periplasmic protease LapG. LapD regulates LapG and controls the ability of this protease to process a large cell surface adhesin protein, LapA. While LapDG orthologs can be identified in diverse

The Pseudomonas Aeruginosa Efflux Pump Mexghi-Opmd Transports A Natural Phenazine That Controls Gene Expression And Biofilm Development, Hassan Sakhtah, Leslie Koyama, Yihan Zhang, Diana K. Morales, Blanche Fields, Alexa Price-Whelan, Deborah Hogan

Dartmouth Scholarship

Redox-cycling compounds, including endogenously produced phenazine antibiotics, induce expression of the efflux pump MexGHI-OpmD in the opportunistic pathogen Pseudomonas aeruginosa Previous studies of P. aeruginosa virulence, physiology, and biofilm development have focused on the blue phenazine pyocyanin and the yellow phenazine-1-carboxylic acid (PCA). In P. aeruginosa phenazine biosynthesis, conversion of PCA to pyocyanin is presumed to proceed through the intermediate 5-methylphenazine-1-carboxylate (5-Me-PCA), a reactive compound that has eluded detection in most laboratory samples. Here, we apply electrochemical methods to directly detect 5-Me-PCA and find that it is transported by MexGHI-OpmD in P. aeruginosa strain PA14 planktonic and biofilm cells. We …

Brief Report: Hiv-1 Gp120 T-Cell Responses Correspond To Infection Outcomes In The Global Iprex Chemoprophylaxis Trial., Peter J Kuebler, Brian I Shaw, Kaitlyn S Leadabrand, Megha L Mehrotra, Robert M Grant, Esper G Kallás, Douglas F Nixon

Microbiology, Immunology, and Tropical Medicine Faculty Publications

Association of HIV-1-specific T-cell responses to infection risk in seronegative individuals is controversial. We quantified and phenotypically characterized gp120-specific T-cell responses in HIV-1 exposed, but uninfected subjects enrolled in the global Pre-exposure Prophylaxis Initiative (iPrEx) chemoprophylaxis trial. IFNγ ELISpot responses were detected in 24% of subjects irrespective of infection outcome. HIV-1 gp120 envelope-specific T-cell responses were more uniformly IFN-γ+TNF-α+Mip-1β+ in persistently seronegative subjects relative to subjects who later seroconverted (median frequency of 76.5% and 66.5%, respectively). IFNγ responses targeted the V2 loop for subjects who remained seronegative. HIV-1 gp120 envelope V2 loop-specific CD8 T-cell responses may help to protect against …

The Role Of Collagen Interacting Proteins In The Pathogenesis Of Filifactor Alocis, Ozioma Salomey Chioma

Loma Linda University Electronic Theses, Dissertations & Projects

Filifactor alocis is a Gram-positive, asaccharolytic; obligate anaerobe that has emerged as a potential periodontal pathogen due to its presence in high numbers in patients who have periodontal disease and least detection in healthy individuals (Kumar et al., 2003, Kumar et al., 2006, Wade, 2011). There is compelling evidence in the literature that demonstrates that F. alocis has virulence properties that may play an important role in infection-induced periodontitis (Abusleme et al., 2013, Griffen et al., 2012, Hutter et al., 2003, Khader et al., 2006, Siqueira and Rocas, 2003, Siqueira et al., 2009). However, there is a gap in our …

Comparative Studies Of Tslp And Il-7 In Normal Early Human Neonatal And Adult B Cell Development, Terry-Ann Milford

Loma Linda University Electronic Theses, Dissertations & Projects

Defining the role of cytokines in promoting human B cell development is important for understanding B cell leukemia and for developing strategies to restore B cell production that is lost during some therapies. The purpose of this study was to investigate the roles of the IL-7R ligands, thymic stromal lymphopoietin (TSLP) and IL- 7, in the early stages of normal postnatal and adult human B cell development. Using novel in vitro and in vivo model systems, we show that TSLP and IL-7 are able to expand B cell precursors individually and in combination from CB hematopoietic stem cells. In this …

Hiv Vaccines: Progress, Limitations And A Crispr/Cas9 Vaccine, Omar A. Garcia Martinez

Biology: Student Scholarship & Creative Works

ABSTRACT: The HIV-1 pandemic continues to thrive due to ineffective HIV-1 vaccines. Historically, the world’s most infectious diseases, such as polio and smallpox, have been eradicated or have come close to eradication due to the advent of effective vaccines. Highly active antiretroviral therapy is able to delay the onset of AIDS but can neither rid the body of HIV-1 proviral DNA nor prevent further transmission. A prophylactic vaccine that prevents the various mechanisms HIV-1 has to evade and attack our immune system is needed to end the HIV-1 pandemic. Recent advances in engineered nuclease systems, like the CRISPR/Cas9 system, have …

Diffuse Traumatic Brain Injury Induces Prolonged Immune Sysregulation And Potentiates Hyperalgesia Following A Peripheral Immune Challenge, Rachel K. Rowe, Gavin I. Ellis, Jordan L. Harrison, Adam D. Bachstetter, Gregory F. Corder, Linda J. Van Eldik, Bradley K. Taylor, Francesc Marti, Jonathan Lifshitz

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Background: Nociceptive and neuropathic pain occurs as part of the disease process after traumatic brain injury (TBI) in humans. Central and peripheral inflammation, a major secondary injury process initiated by the traumatic brain injury event, has been implicated in the potentiation of peripheral nociceptive pain. We hypothesized that the inflammatory response to diffuse traumatic brain injury potentiates persistent pain through prolonged immune dysregulation.

Results: To test this, adult, male C57BL/6 mice were subjected to midline fluid percussion brain injury or to sham procedure. One cohort of mice was analyzed for inflammation-related cytokine levels in cortical biopsies and serum along an …

Signaling In Effector Lymphocytes: Insights Toward Safer Immunotherapy, Kamalakannan Rajasekaran, Matthew J. Riese, Sridhar Rao, Li Wang, Monica Thakar, Charles Sentman, Subramaniam Malarkannan

Dartmouth Scholarship

Receptors on T and NK cells systematically propagate highly complex signaling cascades that direct immune effector functions, leading to protective immunity. While extensive studies have delineated hundreds of signaling events that take place upon receptor engagement, the precise molecular mechanism that differentially regulates the induction or repression of a unique effector function is yet to be fully defined. Such knowledge can potentiate the tailoring of signal transductions and transform cancer immunotherapies. Targeted manipulations of signaling cascades can augment one effector function such as antitumor cytotoxicity while contain the overt generation of pro-inflammatory cytokines that contribute to treatment-related toxicity such as …

Ifn-Γ Receptor And Stat1 Signaling In B Cells Are Central To Spontaneous Germinal Center Formation And Autoimmunity., Phillip P. Domeier, Sathi Babu Chodisetti, Chetna Soni, Stephanie L. Schell, Melinda J. Elias, Eric B. Wong, Timothy K. Cooper, Daisuke Kitamura, Ziaur S.M. Rahman

Department of Microbiology and Immunology Faculty Papers

Spontaneously developed germinal centers (GCs [Spt-GCs]) harbor autoreactive B cells that generate somatically mutated and class-switched pathogenic autoantibodies (auto-Abs) to promote autoimmunity. However, the mechanisms that regulate Spt-GC development are not clear. In this study, we report that B cell-intrinsic IFN-γ receptor (IFN-γR) and STAT1 signaling are required for Spt-GC and follicular T helper cell (Tfh cell) development. We further demonstrate that IFN-γR and STAT1 signaling control Spt-GC and Tfh cell formation by driving T-bet expression and IFN-γ production by B cells. Global or B cell-specific IFN-γR deficiency in autoimmune B6.Sle1b mice leads to significantly reduced Spt-GC and Tfh cell …

A Conserved Dna Repeat Promotes Selection Of A Diverse Repertoire Of Trypanosoma Brucei Surface Antigens From The Genomic Archive., Galadriel Hovel-Miner, Monica R. Mugnier, Benjamin Goldwater, George A. M. Cross, F. Nina Papavasiliou

Microbiology, Immunology, and Tropical Medicine Faculty Publications

African trypanosomes are mammalian pathogens that must regularly change their protein coat to survive in the host bloodstream. Chronic trypanosome infections are potentiated by their ability to access a deep genomic repertoire of Variant Surface Glycoprotein (VSG) genes and switch from the expression of one VSG to another. Switching VSG expression is largely based in DNA recombination events that result in chromosome translocations between an acceptor site, which houses the actively transcribed VSG, and a donor gene, drawn from an archive of more than 2,000 silent VSGs. One element implicated in these duplicative gene conversion events is a DNA repeat …

A Conserved Dna Repeat Promotes Selection Of A Diverse Repertoire Of Trypanosoma Brucei Surface Antigens From The Genomic Archive., Galadriel Hovel-Miner, Monica R Mugnier, Benjamin Goldwater, George A M Cross, F Nina Papavasiliou

Microbiology, Immunology, and Tropical Medicine Faculty Publications

African trypanosomes are mammalian pathogens that must regularly change their protein coat to survive in the host bloodstream. Chronic trypanosome infections are potentiated by their ability to access a deep genomic repertoire of Variant Surface Glycoprotein (VSG) genes and switch from the expression of one VSG to another. Switching VSG expression is largely based in DNA recombination events that result in chromosome translocations between an acceptor site, which houses the actively transcribed VSG, and a donor gene, drawn from an archive of more than 2,000 silent VSGs. One element implicated in these duplicative gene conversion events is a DNA repeat …

Porphyromonas Gingivalis Gingipains Induce A Pro-Inflammatory Extracellular Microenvironment : The Role Of Par-2 And Fibronectin., Jeffrey S. Marschall

Electronic Theses and Dissertations

Periodontitis is a chronic inflammatory disease that is characterized by severe tissue destruction of the gingiva and other tooth supporting structures; if left untreated, tooth loss and disintegration of the alveolar bone occurs. This chronic inflammatory state has been linked to other systemic diseases such as cardiovascular disease, diabetes, rheumatoid arthritis, and Alzheimer’s disease. Porphyromonas gingivalis is the major pathogenic microbe in periodontitis. The main virulence factors of P. gingivalis are the Arg-aa and Lys-aa gingipains, which are proteolytic enzymes implicated in a plethora of activities that allow P. gingivalis to subvert the human immune system in the oral cavity …

The Effect Of Increased Exposure Of Uvc Light On Human Skin Microbiota, T'Kylia S. Moss

Honors Theses

Many methods have been employed to prevent infections from opportunistic pathogens in immunocompromised individuals. Among these are the use of ultraviolet light (UV). In this study, UVC light, was found to have a deleterious effect on specific skin flora. Organisms tested included Acinetobacter baumanii, Candida albicans, Candida kefyr, Corynebacterium renale, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Nutrient agar was used to cultivate most organisms. Blood agar was used for the cultivation of Streptococcus pyogenes and Enterococcus faecalis. Bacterial suspensions were made and utilized to plate each organism onto a set of 7 nutrient agar or …

Redesigning Gfp Reporter System For Utilization In Clostridium Difficile, Laura E. Fitzgerald

Biological Sciences Undergraduate Honors Theses

Clostridium difficile (C. difficile) is a gram-positive bacterium that comprises part of the healthy human gut microbiome. When it gains sufficient access to peptides, C. difficile flourishes and releases tissue-damaging toxins, which cause inflammation of the colon that can develop into a Clostridium difficile Infection (CDI).¹⁰ The Ivey Laboratory believes that the best tactic in preventing CDIs is stopping peptide ingestion, which theoretically could be accomplished by manipulating the oligopeptide permease (App) system.⁷ In order to verify that altering the App system would successfully impede peptide uptake, first the expression of the app Promoter Region ( …

A Novel And Rapid Staphylococcus Aureus Bacterial Identification Method Utilizing Immunomagnetic Beads And Single Cell Laser-Light Scattering, Kaylagh Hollen

All NMU Master's Theses

Staphylococcus aureus is the most commonly isolated human associated bacterial pathogen. It plays an important role in skin and soft-tissue infections, pneumonia, endocarditis, osteomyelitis, foreign-body infections, and sepsis. S. aureus diagnosis and treatment requires a minimum of 24-48. With this in mind, previous studies suggest that faster pathogen identification has been linked to improved patient outcomes. Improved patient outcomes including a reduction in hospitalization time, decreased risk of nosocomial infections, and decreased in medical costs. The impact of faster identification on patient outcome has led us to develop an alternative method of S. aureus identification via ImmunoMagnetic Separation (IMS) and …

Examination Of Cd133 And Cd147 As Cancer Stem Cell Markers, Christopher Mcmahon

All NMU Master's Theses

To date, as many as 14,000 patients in the United States per year are diagnosed with glioblastoma, the most common and most malignant primary brain tumor. Glioblastomas are characterized by their ability to evade treatment on many fronts, thus a novel approach to curative therapies is imperative. A population of cells with stem cell-like properties are found within glioblastoma tumors and drive their initiation and progression. Identification of extracellular markers on these tumor stem cells is thus paramount. The cell surface glycoproteins CD133 and CD147 were examined as potential markers of cancer stem cells found in glioblastoma. Here we found …

Yy1 Is Required For Germinal Center B Cell Development., Anupam Banerjee, Vishal Sindhava, Raja Vuyyuru, Vibha Jha, Suchita Hodewadekar, Tim Manser, Michael L Atchison

Department of Microbiology and Immunology Faculty Papers

YY1 has been implicated as a master regulator of germinal center B cell development as YY1 binding sites are frequently present in promoters of germinal center-expressed genes. YY1 is known to be important for other stages of B cell development including the pro-B and pre-B cells stages. To determine if YY1 plays a critical role in germinal center development, we evaluated YY1 expression during B cell development, and used a YY1 conditional knock-out approach for deletion of YY1 in germinal center B cells (CRE driven by the immunoglobulin heavy chain γ1 switch region promoter; γ1-CRE). We found that YY1 is …

Friendly Fire: Biological Functions And Consequences Of Chromosomal Targeting By Crispr-Cas Systems, Gary E. Heussler, George A. O'Toole

Dartmouth Scholarship

Clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) systems in bacteria and archaea target foreign elements, such as bacteriophages and conjugative plasmids, through the incorporation of short sequences (termed spacers) from the foreign element into the CRISPR array, thereby allowing sequence-specific targeting of the invader. Thus, CRISPR-Cas systems are typically considered a microbial adaptive immune system. While many of these incorporated spacers match targets on bacteriophages and plasmids, a noticeable number are derived from chromosomal DNA. While usually lethal to the self-targeting bacteria, in certain circumstances, these self-targeting spacers can have profound effects in regard to microbial biology, including functions …

Understanding Structural And Functional Mechanisms Of Emi1 Inhibition Of The Anaphase Promoting Complex, Edmond Randall Watson

Theses and Dissertations (ETD)

Healthy, reproducing cells create and destroy proteins in an ordered manner. Both the concentration and localization of protein pools is important to regulate the many cellular processes necessary for the life of the cell. In order to produce new proteins, cells degrade existing materials such as proteins and organelles that are dispensable or troublesome in order to recycle their raw components. Degradation is accomplished largely through two major pathways: in bulk through processes such as autophagy and phagocytosis, or in a targeted manner through the ubiquitin-proteasome pathway. Autophagy utilizes an encompassing body to encapsulate targets and surrounding materials for decomposition …

The Emergence Of The Zika, Chikungunya, And Dengue Viruses In Brazil, The Dominican Republic, And Puerto Rico, Nelson Xavier Del Pilar

Honors Scholar Theses

The Zika, Chikungunya, and Dengue viruses are three emerging viral infections of the 21st century. Outbreaks have occurred in twenty countries, including areas of South America, and territories in the Caribbean. These viral diseases are mosquito-borne infections transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes. The origins of the diseases, viral morphology, and vector transmission will be described in this review as well as symptoms that humans experience, medical testing procedures, and preventative measures. This study will focus on three locations: Brazil, the Dominican Republic, and Puerto Rico. There are many similarities between the three viruses to emphasize, but …