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Uniform TitleInfluence of environmental factors and the host's
susceptibility on the development of listeria monocytogenes infection in the guinea pig model
NamePang, Hoan-Jen Eunice (author), Matthews, Karl (chair), Montville, Thomas (internal member), Tchikindas, Mikhail (internal member), Fratamico, Pina (outside member), Rutgers University, Graduate School-New Brunswick,
Degree Date2007
Date Created2007
SubjectFood Science,
Listeria monocytogenes,
Biological response modifiers
DescriptionListeria monocytogenes is an intracellular pathogen commonly associated with
ready-to-eat foods. Using the guinea pig model, the impact of environmental factors on the infectivity of L. monocytogenes, as well as the impact of a host's immunity, on the development of listerial infection was investigated. Experiments were conducted to determine whether exposure to food environment and improper handling conditions impact the infectivity of L. monocytogenes. Results indicated that the virulence of L. monocytogenes was not influenced by exposure of the pathogen to food or improper handling conditions. In young adult guinea pigs orally challenged with 10² L.
monocytogenes, a 27% infection rate occurred.
Further studies were conducted to determine the impact of immunomodulation of a host's immunity on the development of listerial infection using aged guinea pigs. Flow cytometry analysis showed that daily supplementation with vitamin E significantly increased the level of CD8+ T cells, while cyclosporine A (CsA) treatment resulted in a 25% decrease of CD8+ T cells. HPLC analysis showed that short-term supplementation with vitamin E resulted in an overall 1-fold increase in the plasma alpha-tocopherol concentration. In low-dose (10² CFU) challenged animals, 50% of the control-group animals became infected. Only 22% of animals receiving the orthomolecular dose of vitamin E became infected, whereas animals that were immunosuppressed had an
infection rate of 89%. In the immunosuppressed group three animals (16%) developed listerial infection with a quantifiable bacterial level of 0.3-3 log CFU g(-1) of organ in the spleen and liver. In the high-dose study, the population of L. monocytogenes was consistently 1 log CFU lower in the spleen and liver of animals in the vitamin E group as compared to the control and CsA-treated groups. The level of L. monocytogenes was not significantly different between the control and CsA-treated groups. The results suggest that immunomodulation of the host can influence listerial infection within an aged population of guinea pigs. From a public health perspective, the research indicates that a
low oral dose of L. monocytogenes may pose a human health risk.
ready-to-eat foods. Using the guinea pig model, the impact of environmental factors on the infectivity of L. monocytogenes, as well as the impact of a host's immunity, on the development of listerial infection was investigated. Experiments were conducted to determine whether exposure to food environment and improper handling conditions impact the infectivity of L. monocytogenes. Results indicated that the virulence of L. monocytogenes was not influenced by exposure of the pathogen to food or improper handling conditions. In young adult guinea pigs orally challenged with 10² L.
monocytogenes, a 27% infection rate occurred.
Further studies were conducted to determine the impact of immunomodulation of a host's immunity on the development of listerial infection using aged guinea pigs. Flow cytometry analysis showed that daily supplementation with vitamin E significantly increased the level of CD8+ T cells, while cyclosporine A (CsA) treatment resulted in a 25% decrease of CD8+ T cells. HPLC analysis showed that short-term supplementation with vitamin E resulted in an overall 1-fold increase in the plasma alpha-tocopherol concentration. In low-dose (10² CFU) challenged animals, 50% of the control-group animals became infected. Only 22% of animals receiving the orthomolecular dose of vitamin E became infected, whereas animals that were immunosuppressed had an
infection rate of 89%. In the immunosuppressed group three animals (16%) developed listerial infection with a quantifiable bacterial level of 0.3-3 log CFU g(-1) of organ in the spleen and liver. In the high-dose study, the population of L. monocytogenes was consistently 1 log CFU lower in the spleen and liver of animals in the vitamin E group as compared to the control and CsA-treated groups. The level of L. monocytogenes was not significantly different between the control and CsA-treated groups. The results suggest that immunomodulation of the host can influence listerial infection within an aged population of guinea pigs. From a public health perspective, the research indicates that a
low oral dose of L. monocytogenes may pose a human health risk.
Note[degree] Ph.D.
Note[bibliography] Includes bibliographical references (p. 89-91).
Genretheses
Persistent URLhttp://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.13843
LanguageEnglish
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.