Enterohemorrhagic Escherichia coli O157∶H7 Gene Expression Profiling in Response to Growth in the Presence of Host Epithelia

BACKGROUND: The pathogenesis of enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection is attributed to virulence factors encoded on multiple pathogenicity islands. Previous studies have shown that EHEC O157:H7 modulates host cell signal transduction cascades, independent of toxins and rearrangement of the cytoskeleton. However, the virulence factors and mechanisms responsible for EHEC-mediated subversion of signal transduction remain to be determined. Therefore, the purpose of this study was to first identify differentially regulated genes in response to EHEC O157:H7 grown in the presence of epithelial cells, compared to growth in the absence of epithelial cells (that is, growth in minimal essential tissue culture medium alone, minimal essential tissue culture medium in the presence of 5% CO(2), and Penassay broth alone) and, second, to identify EHEC virulence factors responsible for pathogen modulation of host cell signal transduction. METHODOLOGY/PRINCIPAL FINDINGS: Overnight cultures of EHEC O157:H7 were incubated for 6 hr at 37 degrees C in the presence or absence of confluent epithelial (HEp-2) cells. Total RNA was then extracted and used for microarray analyses (Affymetrix E. coli Genome 2.0 gene chips). Relative to bacteria grown in each of the other conditions, EHEC O157:H7 cultured in the presence of cultured epithelial cells displayed a distinct gene-expression profile. A 2.0-fold increase in the expression of 71 genes and a 2.0-fold decrease in expression of 60 other genes were identified in EHEC O157:H7 grown in the presence of epithelial cells, compared to bacteria grown in media alone. CONCLUSION/SIGNIFICANCE: Microarray analyses and gene deletion identified a protease on O-island 50, gene Z1787, as a potential virulence factor responsible for mediating EHEC inhibition of the interferon (IFN)-gamma-Jak1,2-STAT-1 signal transduction cascade. Up-regulated genes provide novel targets for use in developing strategies to interrupt the infectious process

Biobehavioral Aspects of the COVID-19 Pandemic: A Review

OBJECTIVE: This review highlights the scope and significance of the coronavirus disease 2019 (COVID-19) pandemic with a focus on biobehavioral aspects and critical avenues for research. METHODS: A narrative review of the published research literature was undertaken, highlighting major empirical findings emerging during the first and second waves of the COVID-19 pandemic. RESULTS: Interactions among biological, behavioral, and societal processes were prominent across all regions of the globe during the first year of the COVID-19 emergency. Affective, cognitive, behavioral, socioeconomic, and technological factors all played a significant role in the spread of infection, response precautions, and outcomes of mitigation efforts. Affective symptoms, suicidality, and cognitive dysfunction have been widely described consequences of the infection, the economic fallout, and the necessary public health mitigation measures themselves. The impact of COVID-19 may be especially serious for those living with severe mental illness and/or chronic medical diseases, given the confluence of several adverse factors in a manner that appears to have syndemic potential. CONCLUSIONS: The COVID-19 pandemic has made clear that biological and behavioral factors interact with societal processes in the infectious disease context. Empirical research examining mechanistic pathways from infection and recovery to immunological, behavioral, and emotional outcomes is critical. Examination of how emotional and behavioral factors relate to the pandemic-both as causes and as effects-can provide valuable insights that can improve management of the current pandemic and future pandemics to come

Verocytotoxin-producing Escherichia coli blocks interferon-gamma-activation of signal transducer and activator of transcription-1

Escherichia coli serotype O157:H7 is the leading cause of Verocytotoxin-producing E. coli (VTEC) infections and outbreaks of hemorrhagic colitis in North America. In addition, multiple non-O157:H7 VTEC (such as serotype O113:H21) are also implicated in human disease. Clinical manifestations of VTEC infection include abdominal cramps, self-limiting diarrhea, hemorrhagic colitis, and the hemolytic-uremic syndrome. VTEC pathogenesis is attributed to multiple virulence factors, including Verocytotoxins, bacterial adhesion, effector proteins, and evasion of the host immune system. Interferon (IFN)-γ is a pro-inflammatory cytokine produced by CD4+ T cells, which are recruited to sites of bacterial infection. Signalling of this cytokine through Jaks-1 and -2 and subsequent STAT-1 tyrosine phosphorylation is required for transcriptional activation of immune function genes, which combat infection. In vitro tissue culture techniques have shown that VTEC O157:H7 and O113:H21, but not enteropathogenic E. coli serotype O127:H6 or non-pathogenic E. coli strain HB101, disrupt the IFNγ-Jak1,2-STAT-1 signalling cascade, as assayed using tyrosine phosphorylation of STAT-1 as a read-out. The inhibitory factor of STAT-1 tyrosine phosphorylation is bacterial in nature, the expression of which is enhanced following bacterial growth in the presence of epithelial cells. This factor is present in conditioned medium, in which it is heat, proteinase K, and trypsin insensitive. In addition, regulatory molecules of the IFNγ-Jak1,2-STAT-1, which include PTPs, SOCS and PIAS, also are not involved in pathogen subversion of this signalling cascade. The probiotic, Lactobacillus helveticus strain R0052 protects cultured epithelial cells from VTEC-induced disruption of STAT-1 activation, thereby representing a potential for use of probiotics in the management of VTEC infections. In summary, suppression of cytokine-induced transcription factors following VTEC challenge represents an immune evasion strategy of this bacterial enteropathogen. Therefore, identification and characterization of the bacterial factor involved will help to elucidate the pathobiology of VTEC infection.Ph.D

Getting to Know Your Microbiota in Health and Disease

<p><strong>Review of:</strong><em> </em><em>The Human Microbiota: How Microbial Communities Affect Health and Disease</em>; David N. Fredricks (ed.); (2013). John Wiley and Sons, Hoboken, NJ. 362 pages.</p

Clicker Student Response Systems: Dedicated Physical Devices or Web-Enabled Systems that Allow Student to Bring Their Own Device (BYOD)

The implementation of clickers and clicker questions into classroom teaching is a well-established active-learning technique that provides more interactive classrooms and engages students with course content.  Throughout the years, however, the actual clickers themselves have undergone an evolution from physical hand-held devices to web-based applications.  This review explores the general advantages and disadvantages of two-main clicker styles, dedicated physical devises and web enabled clickers

Introductory Immunology: Begin the Journey

<p><strong>Review of</strong><em>: </em><em>Primer</em><em> to the Immune Response</em>, 2^nd ed.; Tak Mak, Mary Saunders, and Bradley Jett; (2014). Elsevier Inc., London, UK. 702 pages.</p

Anchoring sustainable teaching practices with foundational course design

Amidst a fair amount of disruptions within education, teaching, and learning in the past few years, there still remains some certainty. Core educational and instructional practices such as the fundamental elements of course design including alignment of assessments, inclusive classroom environments, active learning with student engagement, transparency with teaching philosophies, and clear expectations and guidelines have always and will always be important in teaching and learning. This poster presentation will aim to share some practices, strategies, and examples in each of the areas outlined above. This will serve as a survey of different strategies that instructors could consider implementing and/or will aim to reinforce their existing practices. These examples will come from responses to pandemic teaching through to generative-AI, as well as through the literature. Through these examples, the goal is to demonstrate how small changes in responses to disruptions can allow for adaptation. In addition, to demonstrate how a small change in response to one disruption is applicable in response to another disruption. The emphasis on a small change(s) is meant to reinforce the importance of a strong foundational course design that can withstand disruptions