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Cellular immune response to Marek's disease: listeriosis as a model of study
Abstract:
The immune response of chickens to Listeria monocytogenes was studied as a potential model for cell-mediated immunocompetence. Chickens genetically resistant and susceptible to Marek's disease (MD) did not differ in their ability to survive Listeria, although during the early stages of infection the bacteria replicated more readily in MD-susceptible chickens. MD-susceptible chickens responded earlier than MD-resistant chickens, and with equal or increased intensity, in assays of various components of the cell-mediated reaction. These assays included T-cell activation, delayed-type hypersensitivity, and macrophage activation. These data indicate that genetic resistance or susceptibility to MD is not wholly dependent on the innate immunocompetence of the host. Co-infection with Listeria was used to measure cellular immunocompetence in MD-infected chickens. MD virus had no effect on the ability of host macrophages to control the growth of Listeria. The cell-mediated response was suppressed in MD-susceptible chickens. The occurrence of spleen cell proliferation, followed by marked suppression of the effector arm of the immune response in susceptible but not resistant chickens, indicated the possibility of an active suppressor-cell population associated with genetic susceptibility to MD.
Insights
Chicken immune responses to Listeria monocytogenes reveal insights into cell-mediated immunity. Susceptibility to Marek
Area of Science:
- Immunology
- Avian Health
- Infectious Disease
Background:
- Cell-mediated immunity is crucial for controlling intracellular pathogens like Listeria monocytogenes.
- Marek's disease (MD) is a significant lymphoproliferative disease in chickens, impacting their immune system.
- Understanding host-pathogen interactions is key to improving poultry health and disease resistance.
Purpose of the Study:
- To investigate the chicken immune response to Listeria monocytogenes as a model for cell-mediated immunocompetence.
- To compare the immune responses of chickens genetically resistant and susceptible to Marek's disease (MD).
- To assess the impact of MD virus infection on cellular immunocompetence.
Main Methods:
- Chickens with differing genetic resistance to Marek's disease were infected with Listeria monocytogenes.
- Cell-mediated immune responses were evaluated using assays for T-cell activation, delayed-type hypersensitivity, and macrophage activation.
- Co-infection with Listeria was used to measure cellular immunocompetence in MD-infected chickens.
Main Results:
- Listeria monocytogenes replicated more readily in MD-susceptible chickens during early infection.
- MD-susceptible chickens exhibited earlier and more intense cell-mediated responses compared to MD-resistant chickens.
- MD virus did not impair macrophage control of Listeria, but the cell-mediated response was suppressed in MD-susceptible chickens, suggesting an active suppressor-cell population.
Conclusions:
- Genetic resistance to MD is not solely determined by innate immunocompetence.
- MD-susceptible chickens may possess an active suppressor-cell population that impairs their cell-mediated immune response.
- Listeria monocytogenes serves as a valuable model for studying cell-mediated immunity and its modulation by diseases like MD in chickens.