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Julia Pridgeon - One of the best experts on this subject based on the ideXlab platform.

  • attempt to develop live attenuated bacterial vaccines by selecting Resistance to gossypol proflavine hemisulfate novobiocin or ciprofloxacin
    Vaccine, 2013
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Mediha Yildirimaksoy
    Abstract:

    In an attempt to develop attenuated bacteria as potential live vaccines, four chemicals (gossypol, proflavine hemisulfate, novobiocin, and ciprofloxacin) were used to modify the following four genera of bacteria through chemical-Resistance Strategy: (1) Aeromonas hydrophila (9 isolates); (2) Edwardsiella tarda (9 isolates); (3) Streptococcus iniae (9 isolates); and (4) S. agalactiae (11 isolates). All bacteria used in this study were able to develop high Resistance to gossypol. However, only some bacteria were able to develop Resistance to proflavine hemisulfate, novobiocin, or ciprofloxacin. When the virulence of resistant bacteria was tested in tilapia or catfish, none of the gossypol-resistant isolate was attenuated, whereas majority of the proflavine hemisulfate-resistant isolates were attenuated. However, all proflavine hemisulfate-attenuated bacteria failed to provide significant protection to fish. Eight novobiocin- or ciprofloxacin-resistant Gram-positive bacteria (S. agalactiae and S. inaie) were found to be attenuated. However, none of them offered protection higher than 70%. Of seven attenuated novobiocin- or ciprofloxacin-resistant Gram-negative isolates (A. hydrophila and E. tarda), only one (novobiocin-resistant E. tarda 30305) was found to safe and highly efficacious. When E. tarda 30305-novo vaccinated Nile tilapia were challenged by its virulent E. tarda 30305, relative percent of survival of vaccinated fish at 14- and 28-days post vaccination (dpv) was 100% and 92%, respectively. Similarly, E. tarda 30305-novo offered 100% protection to channel catfish against challenges with virulent parent isolate E. tarda 30305 at both 14- and 28-dpv. Our results suggest that the development of live attenuated bacterial vaccines that are safe and efficacious is challenging, although it is feasible.

  • attenuation of a virulent aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin resistant strain
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Kunwar K. Srivastava, M Yildirimaksoy, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P < 0·05) less than that of AH11P. In vitro motility assay revealed that AH11NOVO was nonmotile, whereas AH11P was motile. AH11NOVO had significantly (P < 0·05) lower in vitro chemotactic response to catfish mucus than that of AH11P. Although the ability of AH11NOVO to attach catfish gill cells was similar to that of AH11P, the ability of AH11NOVO to invade catfish gill cells was significantly (P < 0·05) lower than that of AH11P. Conclusions The novobiocin-resistant AH11NOVO is attenuated and different from its parent AH11P in pathogenicity. Significance and Impact of the Study The significantly lower chemotactic response and invasion ability of AH11NOVO compared with that of its virulent parent strain AH11P might shed light on the pathogenesis of Aer. hydrophila.

  • Attenuation of a virulent Aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin-resistant strain.
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, M. Yildirim-aksoy, Phillip H. Klesius, Kunwar K. Srivastava, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P 

P.g. Reddy - One of the best experts on this subject based on the ideXlab platform.

  • attenuation of a virulent aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin resistant strain
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Kunwar K. Srivastava, M Yildirimaksoy, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P < 0·05) less than that of AH11P. In vitro motility assay revealed that AH11NOVO was nonmotile, whereas AH11P was motile. AH11NOVO had significantly (P < 0·05) lower in vitro chemotactic response to catfish mucus than that of AH11P. Although the ability of AH11NOVO to attach catfish gill cells was similar to that of AH11P, the ability of AH11NOVO to invade catfish gill cells was significantly (P < 0·05) lower than that of AH11P. Conclusions The novobiocin-resistant AH11NOVO is attenuated and different from its parent AH11P in pathogenicity. Significance and Impact of the Study The significantly lower chemotactic response and invasion ability of AH11NOVO compared with that of its virulent parent strain AH11P might shed light on the pathogenesis of Aer. hydrophila.

  • Attenuation of a virulent Aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin-resistant strain.
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, M. Yildirim-aksoy, Phillip H. Klesius, Kunwar K. Srivastava, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P 

Phillip H. Klesius - One of the best experts on this subject based on the ideXlab platform.

  • attempt to develop live attenuated bacterial vaccines by selecting Resistance to gossypol proflavine hemisulfate novobiocin or ciprofloxacin
    Vaccine, 2013
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Mediha Yildirimaksoy
    Abstract:

    In an attempt to develop attenuated bacteria as potential live vaccines, four chemicals (gossypol, proflavine hemisulfate, novobiocin, and ciprofloxacin) were used to modify the following four genera of bacteria through chemical-Resistance Strategy: (1) Aeromonas hydrophila (9 isolates); (2) Edwardsiella tarda (9 isolates); (3) Streptococcus iniae (9 isolates); and (4) S. agalactiae (11 isolates). All bacteria used in this study were able to develop high Resistance to gossypol. However, only some bacteria were able to develop Resistance to proflavine hemisulfate, novobiocin, or ciprofloxacin. When the virulence of resistant bacteria was tested in tilapia or catfish, none of the gossypol-resistant isolate was attenuated, whereas majority of the proflavine hemisulfate-resistant isolates were attenuated. However, all proflavine hemisulfate-attenuated bacteria failed to provide significant protection to fish. Eight novobiocin- or ciprofloxacin-resistant Gram-positive bacteria (S. agalactiae and S. inaie) were found to be attenuated. However, none of them offered protection higher than 70%. Of seven attenuated novobiocin- or ciprofloxacin-resistant Gram-negative isolates (A. hydrophila and E. tarda), only one (novobiocin-resistant E. tarda 30305) was found to safe and highly efficacious. When E. tarda 30305-novo vaccinated Nile tilapia were challenged by its virulent E. tarda 30305, relative percent of survival of vaccinated fish at 14- and 28-days post vaccination (dpv) was 100% and 92%, respectively. Similarly, E. tarda 30305-novo offered 100% protection to channel catfish against challenges with virulent parent isolate E. tarda 30305 at both 14- and 28-dpv. Our results suggest that the development of live attenuated bacterial vaccines that are safe and efficacious is challenging, although it is feasible.

  • attenuation of a virulent aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin resistant strain
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Kunwar K. Srivastava, M Yildirimaksoy, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P < 0·05) less than that of AH11P. In vitro motility assay revealed that AH11NOVO was nonmotile, whereas AH11P was motile. AH11NOVO had significantly (P < 0·05) lower in vitro chemotactic response to catfish mucus than that of AH11P. Although the ability of AH11NOVO to attach catfish gill cells was similar to that of AH11P, the ability of AH11NOVO to invade catfish gill cells was significantly (P < 0·05) lower than that of AH11P. Conclusions The novobiocin-resistant AH11NOVO is attenuated and different from its parent AH11P in pathogenicity. Significance and Impact of the Study The significantly lower chemotactic response and invasion ability of AH11NOVO compared with that of its virulent parent strain AH11P might shed light on the pathogenesis of Aer. hydrophila.

  • Attenuation of a virulent Aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin-resistant strain.
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, M. Yildirim-aksoy, Phillip H. Klesius, Kunwar K. Srivastava, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P 

Larry L. Murdock - One of the best experts on this subject based on the ideXlab platform.

  • Deterministic Modeling of Negative Cross-Resistance Strategies for use in Transgenic Host-plant Resistance
    Journal of theoretical biology, 2000
    Co-Authors: Barry R. Pittendrigh, Patrick J. Gaffney, Larry L. Murdock
    Abstract:

    Negative cross-Resistance refers to a situation in which an insect population that is tolerant (resistant, virulent) to one insecticide is hyper-sensitive (avirulent) to a second insecticide and insects hyper-sensitive to the first compound are tolerant to the second. Most research dealing with negative cross-Resistance has focused on the molecular biology and chemical aspects of this phenomenon. We explored, from a population genetics perspective, whether negative cross-Resistance is feasible in the control of an insect population. As a first step towards this goal, we used a deterministic approach to evaluate different control scenarios and to identify some of the potential limitations of negative cross-Resistance strategies. Specifically, we investigated how such approaches could be used in a host-plant Resistance program. Homo- and heterozygous insect fitness influenced the effectiveness of the toxins in controlling the insect population. The negative cross-Resistance Strategy was most useful when the insects' virulence to both host-plant toxins was recessive. When virulence was dominant, there were many periods when intervention with an outside (or third) class of compounds, which had a different mode of action than that of the negative cross-Resistance compounds, was needed to control the insect population. The greater the number of insect generations per plant generation, in the absence of immigration or emigration in the insect population, the greater the requirement for intervention with a third class of compound to maintain effective control of the insect population. When the toxins were rotated every insect generation, and virulence in the insect was recessive to both toxins, effective control of the insect population was maintained without intervention of a third class of compounds.

Kunwar K. Srivastava - One of the best experts on this subject based on the ideXlab platform.

  • attenuation of a virulent aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin resistant strain
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, Phillip H. Klesius, Kunwar K. Srivastava, M Yildirimaksoy, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P < 0·05) less than that of AH11P. In vitro motility assay revealed that AH11NOVO was nonmotile, whereas AH11P was motile. AH11NOVO had significantly (P < 0·05) lower in vitro chemotactic response to catfish mucus than that of AH11P. Although the ability of AH11NOVO to attach catfish gill cells was similar to that of AH11P, the ability of AH11NOVO to invade catfish gill cells was significantly (P < 0·05) lower than that of AH11P. Conclusions The novobiocin-resistant AH11NOVO is attenuated and different from its parent AH11P in pathogenicity. Significance and Impact of the Study The significantly lower chemotactic response and invasion ability of AH11NOVO compared with that of its virulent parent strain AH11P might shed light on the pathogenesis of Aer. hydrophila.

  • Attenuation of a virulent Aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin-resistant strain.
    Journal of Applied Microbiology, 2012
    Co-Authors: Julia Pridgeon, M. Yildirim-aksoy, Phillip H. Klesius, Kunwar K. Srivastava, P.g. Reddy
    Abstract:

    Aim To determine whether novobiocin Resistance Strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. Methods and Results A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of Resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P