The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform

Gary M. Dunny - One of the best experts on this subject based on the ideXlab platform.

  • Enterococcus faecalis sex pheromone cCF10 enhances conjugative plasmid transfer in vivo
    mBio, 2018
    Co-Authors: Helmut Hirt, Kerryl E. Greenwood-quaintance, Melissa J. Karau, Lisa M. Till, Purna C. Kashyap, Robin Patel, Gary M. Dunny
    Abstract:

    ABSTRACT Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF− recipient) in a Germfree Mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum. IMPORTANCE Horizontal gene transfer is a major factor in the biology of Enterococcus faecalis, an important nosocomial pathogen. Previous studies showing efficient conjugative plasmid transfer in the gastrointestinal (GI) tracts of experimental animals did not examine how the enterococcal sex pheromone response impacts the efficiency of transfer. Our study demonstrates for the first time pheromone-enhanced, high-frequency plasmid transfer of E. faecalis plasmid pCF10 in a Mouse model in the absence of antibiotic or bacteriocin selection. Pheromone production by recipients dramatically increased plasmid transfer in Germfree mice colonized initially with recipients, followed by donors. The presence of a coresident community of common gut microbes did not significantly reduce in vivo plasmid transfer between enterococcal donors and recipients. In mice colonized with enterococcal recipients, we detected plasmid transfer in the intestinal tract within 5 h of addition of donors, before transconjugants could be cultured from feces. Surprisingly, pCF10 carriage provided a competitive fitness advantage unrelated to antibiotic resistance or bacteriocin production.

  • Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo
    American Society for Microbiology, 2018
    Co-Authors: Helmut Hirt, Kerryl E. Greenwood-quaintance, Melissa J. Karau, Lisa M. Till, Purna C. Kashyap, Robin Patel, Gary M. Dunny, Peter E. Greenberg
    Abstract:

    Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF− recipient) in a Germfree Mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum

Edward T Ryan - One of the best experts on this subject based on the ideXlab platform.

  • optimizing the Germfree Mouse model for in vivo evaluation of oral vibrio cholerae vaccine and vector strains
    Infection and Immunity, 2000
    Co-Authors: Thomas I Crean, Manohar John, Stephen B Calderwood, Edward T Ryan
    Abstract:

    The Germfree Mouse model of Vibrio cholerae infection can be used to judge immune responses to V. cholerae vaccine and vector strains. In the original model, a single oral inoculation was administered on day 0, a booster oral inoculation was administered on day 14, and immune responses were analyzed with samples collected on day 28. Unfortunately, immune responses in this model frequently were low level, and interanimal variability occurred. In order to improve this model, we evaluated various primary and booster V. cholerae inoculation schedules. The most prominent systemic and mucosal antibody responses were measured in mice that received a multiple primary inoculation series on days 0, 2, 4, and 6 and booster inoculations on days 28 and 42. These modifications result in improved preliminary evaluation of V. cholerae vaccine and vector strains in mice.

  • development of a Germfree Mouse model of vibrio cholerae infection
    Infection and Immunity, 1996
    Co-Authors: Joan R Butterton, Edward T Ryan, R A Shahin, Stephen B Calderwood
    Abstract:

    A Mouse model of Vibrio cholerae infection was successfully developed with Germfree mice. Three- to four-week-old Germfree mice were orally inoculated with strains of V. cholerae to be tested and then moved to normal housing after inoculation. Stool culture, measurement of serum vibriocidal antibody titers, and determination of immune responses to the cholera toxin B subunit demonstrated that Germfree mice are readily colonized by V cholerae and develop systemic and mucosal immune responses to antigens expressed by these organisms. Immune responses to the B subunit of Shiga toxin 1, which was expressed from a V. cholerae vaccine vector, were less pronounced. This model should be valuable for studying immune responses to V. cholerae infection and immunization, including responses to heterologous antigens expressed by cholera vector strains.

Stephen B Calderwood - One of the best experts on this subject based on the ideXlab platform.

  • optimizing the Germfree Mouse model for in vivo evaluation of oral vibrio cholerae vaccine and vector strains
    Infection and Immunity, 2000
    Co-Authors: Thomas I Crean, Manohar John, Stephen B Calderwood, Edward T Ryan
    Abstract:

    The Germfree Mouse model of Vibrio cholerae infection can be used to judge immune responses to V. cholerae vaccine and vector strains. In the original model, a single oral inoculation was administered on day 0, a booster oral inoculation was administered on day 14, and immune responses were analyzed with samples collected on day 28. Unfortunately, immune responses in this model frequently were low level, and interanimal variability occurred. In order to improve this model, we evaluated various primary and booster V. cholerae inoculation schedules. The most prominent systemic and mucosal antibody responses were measured in mice that received a multiple primary inoculation series on days 0, 2, 4, and 6 and booster inoculations on days 28 and 42. These modifications result in improved preliminary evaluation of V. cholerae vaccine and vector strains in mice.

  • development of a Germfree Mouse model of vibrio cholerae infection
    Infection and Immunity, 1996
    Co-Authors: Joan R Butterton, Edward T Ryan, R A Shahin, Stephen B Calderwood
    Abstract:

    A Mouse model of Vibrio cholerae infection was successfully developed with Germfree mice. Three- to four-week-old Germfree mice were orally inoculated with strains of V. cholerae to be tested and then moved to normal housing after inoculation. Stool culture, measurement of serum vibriocidal antibody titers, and determination of immune responses to the cholera toxin B subunit demonstrated that Germfree mice are readily colonized by V cholerae and develop systemic and mucosal immune responses to antigens expressed by these organisms. Immune responses to the B subunit of Shiga toxin 1, which was expressed from a V. cholerae vaccine vector, were less pronounced. This model should be valuable for studying immune responses to V. cholerae infection and immunization, including responses to heterologous antigens expressed by cholera vector strains.

Helmut Hirt - One of the best experts on this subject based on the ideXlab platform.

  • Enterococcus faecalis sex pheromone cCF10 enhances conjugative plasmid transfer in vivo
    mBio, 2018
    Co-Authors: Helmut Hirt, Kerryl E. Greenwood-quaintance, Melissa J. Karau, Lisa M. Till, Purna C. Kashyap, Robin Patel, Gary M. Dunny
    Abstract:

    ABSTRACT Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF− recipient) in a Germfree Mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum. IMPORTANCE Horizontal gene transfer is a major factor in the biology of Enterococcus faecalis, an important nosocomial pathogen. Previous studies showing efficient conjugative plasmid transfer in the gastrointestinal (GI) tracts of experimental animals did not examine how the enterococcal sex pheromone response impacts the efficiency of transfer. Our study demonstrates for the first time pheromone-enhanced, high-frequency plasmid transfer of E. faecalis plasmid pCF10 in a Mouse model in the absence of antibiotic or bacteriocin selection. Pheromone production by recipients dramatically increased plasmid transfer in Germfree mice colonized initially with recipients, followed by donors. The presence of a coresident community of common gut microbes did not significantly reduce in vivo plasmid transfer between enterococcal donors and recipients. In mice colonized with enterococcal recipients, we detected plasmid transfer in the intestinal tract within 5 h of addition of donors, before transconjugants could be cultured from feces. Surprisingly, pCF10 carriage provided a competitive fitness advantage unrelated to antibiotic resistance or bacteriocin production.

  • Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo
    American Society for Microbiology, 2018
    Co-Authors: Helmut Hirt, Kerryl E. Greenwood-quaintance, Melissa J. Karau, Lisa M. Till, Purna C. Kashyap, Robin Patel, Gary M. Dunny, Peter E. Greenberg
    Abstract:

    Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF− recipient) in a Germfree Mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum

Paula I Watnick - One of the best experts on this subject based on the ideXlab platform.

  • vibrio cholerae phosphoenolpyruvate phosphotransferase system control of carbohydrate transport biofilm formation and colonization of the Germfree Mouse intestine
    Infection and Immunity, 2010
    Co-Authors: Laetitia Houot, Sarah Chang, Cedric Absalon, Paula I Watnick
    Abstract:

    The bacterial phosphoenolpyruvate phosphotransferase system (PTS) is a highly conserved phosphotransfer cascade whose components modulate many cellular functions in response to carbohydrate availability. Here, we further elucidate PTS control of Vibrio cholerae carbohydrate transport and activation of biofilm formation on abiotic surfaces. We then define the role of the PTS in V. cholerae colonization of the adult Germfree Mouse intestine. We report that V. cholerae colonizes both the small and large intestines of the Mouse in a distribution that does not change over the course of a month-long experiment. Because V. cholerae possesses many PTS-independent carbohydrate transporters, the PTS is not essential for bacterial growth in vitro. However, we find that the PTS is essential for colonization of the Germfree adult Mouse intestine and that this requirement is independent of PTS regulation of biofilm formation. Therefore, competition for PTS substrates may be a dominant force in the success of V. cholerae as an intestinal pathogen. Because the PTS plays a role in colonization of environmental surfaces and the mammalian intestine, we propose that it may be essential to successful transit of V. cholerae through its life cycle of pathogenesis and environmental persistence.

  • Control of Carbohydrate Transport, Biofilm Formation, and Colonization of the Germfree Mouse Intestine
    2009
    Co-Authors: Laetitia Houot, Sarah Chang, Cedric Absalon, Paula I Watnick
    Abstract:

    The bacterial phosphoenolpyruvate phosphotransferase system (PTS) is a highly conserved phosphotransfer cascade whose components modulate many cellular functions in response to carbohydrate availability. Here, we further elucidate PTS control of Vibrio cholerae carbohydrate transport and activation of biofilm formation on abiotic surfaces. We then define the role of the PTS in V. cholerae colonization of the adult Germfree Mouse intestine. We report that V. cholerae colonizes both the small and large intestines of the Mouse in a distribution that does not change over the course of a month-long experiment. Because V. cholerae possesses many PTS-independent carbohydrate transporters, the PTS is not essential for bacterial growth in vitro. However, we find that the PTS is essential for colonization of the Germfree adult Mouse intestine and that this requirement is independent of PTS regulation of biofilm formation. Therefore, competition for PTS substrates may be a dominant force in the success of V. cholerae as an intestinal pathogen. Because the PTS plays a role in colonization of environmental surfaces and the mammalian intestine, we propose that it may be essential to successful transit of V. cholerae through its life cycle of pathogenesis and environmental persistence. In water, in soil, and in the eukaryotic host, bacteria survive by monitoring their environment and continuously adjusting their nutrient uptake and catabolism machinery to mirror en