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  • Undergraduate Poster Abstracts
  • Microbiology

    THU-G21 TRANSCRIPTIONAL REPRESSION OF HILA BY PHOP IN SALMONELLA ENTERICA SEROVAR TYPHIMURIUM

    • Alexander Palmer ;
    • James Slauch ;

    THU-G21

    TRANSCRIPTIONAL REPRESSION OF HILA BY PHOP IN SALMONELLA ENTERICA SEROVAR TYPHIMURIUM

    Alexander Palmer, James Slauch.

    University of Illinois at Urbana-Champaign, Urbana, IL.

    Salmonella enterica serovar typhimurium is one of the most common foodborne pathogens in the world. Orally acquired, the bacteria travel to the most distal portion of the small intestine where they activate the salmonella pathogenicity island (SPI1) type 3 secretion system (T3SS). This needle-like complex is used to inject effector proteins into the host cell, leading to bacterial invasion and inflammatory diarrhea. Research has shown that the SPI1 T3SS is tightly regulated, and many of those regulatory signals act through HilA, the main activator of the SPI1 T3SS. PhoP is a global regulatory protein that is known to repress hilA transcription, but how that repression occurs is unknown. Our goal is to identify how PhoP mediates repression of hilA. Here, using transcriptional fusions, we narrow down the region of the hilA promoter required for PhoP repression, and show that one mechanism of repression depends on known hilA activators. We will proceed to identify how PhoP represses hilA transcription using epistatic and mutational analysis followed by biochemical assays to confirm our results.

    FRI-G20 CONSEQUENCES OF INTERACTION BETWEEN THE HOST MICROBIOTA AND PICORNAVIRUSES

    • Elizabeth Aguilera ;
    • Palmy Jesudhasan ;
    • Julie Pfeiffer ;

    FRI-G20

    CONSEQUENCES OF INTERACTION BETWEEN THE HOST MICROBIOTA AND PICORNAVIRUSES

    Elizabeth Aguilera, Palmy Jesudhasan, Julie Pfeiffer.

    The University of Texas Southwestern Medical Center, Dallas, TX.

    The Picornaviridae family is composed of over 50 viruses organized into 29 genera. These viruses can cause a broad range of symptoms ranging from encephalomyocarditis to gastrointestinal complications. On infection, these viruses encounter various bacterial species that make up the host microbiota. However, outcomes of interaction between host microbiota and picornaviruses are still not understood. Previous work in our lab has determined that poliovirus and coxsackievirus B3 (CVB3), both enteric viruses, have enhanced stability when incubated at 37 °C with bacteria or their bacterial surface polysaccharides, such as peptidoglycan and lipopolysaccharide. Furthermore, Theiler’s murine encephalomyocarditis (TMEV) virus, a cardiovirus, also had enhanced stability in the presence of specific bacterial strains, including Bacillus cereus and Bacillus subtilis. Therefore, we hypothesize that bacteria broadly enhance viral stability and infectivity of other picornaviruses. Currently, we are testing picornaviruses from 3 separate genera: Enterovirus (poliovirus, CVB3, rhinovirus and enterovirus D68), Kobuvirus (aichivirus), and Cardiovirus (TMEV and encephalomyocarditis virus). To test our hypothesis, we will use in vitro stability assays with various bacterial species. For a more biologically relevant perspective, we will use bacteria isolated from the feces of mice. These bacteria will be representative of the murine gut microbiota. So far, we have determined that specific bacterial species enhance stability of a subset of picornaviruses. Overall, this work has the potential to define which and how bacterial species promote picornavirus infection within the host. Ultimately, understanding virus-host interactions can define mechanisms by which viral replication and pathogenesis are enhanced and could lead to unique antiviral strategies.

    FRI-G35 GROWTH PHASE REGULATION OF YEAST PHOSPHOLIPID BIOSYNTHETIC GENES VIA PROTEIN DEGRADATION

    • Bryan Salas-Santiago ;
    • John Lopes ;

    FRI-G35

    GROWTH PHASE REGULATION OF YEAST PHOSPHOLIPID BIOSYNTHETIC GENES VIA PROTEIN DEGRADATION

    Bryan Salas-Santiago, John Lopes.

    University of Massachusetts, Amherst, Amherst, MA.

    Saccharomyces cerevisiae is a unicellular model for the study of biological processes in eukaryotes. In our lab, we use S. cerevisiae to understand the mechanisms of regulation of gene expression. Most phospholipid (PL) biosynthetic genes in yeast are repressed in response to inositol. Yeast mutants that overproduce inositol (Opi-) have previously been shown to affect repression of PL biosynthetic gene expression. The Opi- phenotype correlates with constitutive overexpression of the INO1 gene, which is responsible for the synthesis of inositol. Our lab screened a conditional-shutdown essential gene collection that identified 121 mutants with an Opi- phenotype. This screen identified previously unknown novel functions that affect PL synthesis such as protein degradation through the 20S proteasome. Surprisingly, these mutants did not show a repression defect in the presence of inositol. However, under activating conditions (absence of inositol) INO1 is also growth phase regulated, being repressed at the stationary phase of growth. We tested 2 proteasome subunits that were identified in the screen. These 2 subunits were required for repression in stationary phase. We are focused on defining the mechanism for how the proteasome complex affects expression of PL biosynthetic genes during growth phase regulation.

    THU-G35 ROLES OF THE MATRIX PROTEIN IN CELL-ASSOCIATED MEASLES VIRUS EPITHELIAL SPREAD

    • Crystal Mendoza ;
    • Mathieu Mateo ;
    • Roberto Cattaneo ;

    THU-G35

    ROLES OF THE MATRIX PROTEIN IN CELL-ASSOCIATED MEASLES VIRUS EPITHELIAL SPREAD

    Crystal Mendoza1, Mathieu Mateo2, Roberto Cattaneo2.

    1Mayo Clinic Graduate School, Rochester, MN, 2Mayo Clinic, Rochester, MN.

    Measles’ recent re-emergence in insufficiently vaccinated populations in Europe and North America has reminded us that measles virus (MV) is the most contagious human virus known. In humans and experimentally infected monkeys, MV infections are always strictly cell-associated for spread in activated immune cells and airway epithelia. We use well-differentiated primary human airway epithelial (HAE) sheets to characterize the epithelial phase of MV infections. In HAE, MV infectious centers grow without syncytia formation, cytopathic effect, and trans-epithelial resistance is maintained. In these centers, MV-expressed green fluorescent protein flows through openings that form on the lateral surfaces of columnar epithelial cells. MV spread also depends on the contact of the cytoplasmic tail of the MV epithelial receptor nectin-4 with afadin, a protein that contacts the actin cytoskeleton. Here, we examine how the viral matrix protein organizes the assembly of viral components. Having observed that matrix accumulates at infected-to-uninfected cell borders, we characterized how it interacts with the viral fusion apparatus, viral ribonucleocapsid, and the actin cytoskeleton. Guided by the atomic structure of a matrix protein from a related paramyxovirus, we have identified and mutated MV matrix protein residues that could govern these interactions. We generated recombinant MV with mutations in the matrix gene and measured their membrane association, actin binding, and fusion inhibiting functions in stable cell lines. To characterize the relevance of these interactions for viral spread in the airways, we will infect HAE with the mutant viruses. These studies will characterize which cellular mechanisms govern rapid MV epithelial spread.

    THU-G34 ASSESSMENT OF THE EFFECTIVENESS OF THE GUADALUPE WATER TREATMENT PLANT IN REMOVING ESCHERICHIA COLI AND INTESTINAL PARASITES

    • Susana Portillo ;
    • Melissa Solano Barquero ;
    • Luz Chacon Jimenez ;

    THU-G34

    ASSESSMENT OF THE EFFECTIVENESS OF THE GUADALUPE WATER TREATMENT PLANT IN REMOVING ESCHERICHIA COLI AND INTESTINAL PARASITES

    Susana Portillo1, Melissa Solano Barquero2, Luz Chacon Jimenez2.

    The University of Texas at El Paso, El Paso, TX, 2Universidad de Costa Rica, San Jose, CR.

    Access to potable water free of contaminants is essential for a healthy lifestyle. Many Latin American countries lack access to potable water or quality potable water. Under these conditions, pathogenic microorganisms can easily be transmitted to consumers. We know that some microorganisms are resistant to many of the water treatments used, posing a threat to healthcare. In this study, water samples were assessed from 6 different time points from the water treatment plant located in Guadalupe, Costa Rica, for their efficacy in removing harmful pathogens. We use flocculation, Filta-Max, immunomagnetic separation, and immunofluorescence to detect Giardia spp. and Cryptosporidium spp. parasites. The most probable number technique was also implemented in both the presumptive and confirmatory phase to detect pathogenic Escherichia coli gene strains. By using these techniques, we were able to determine that, even after the harsh treatment the drinking water was given, both types of parasites were found at more than one time point, and one pathogenic E. coli gene, heat-labile enterotoxin (LT), was found. More importantly, 2 Cryptosporidium spp. were found in the water at the exit time point. From this point, water is distributed to households. This shows that currently implemented water treatments are not sufficient to remove harmful pathogens, raising public health concerns.