Immune Status and the Development of Listeria monocytogenes Infection in Aged and Young Guinea Pigs

Abstract

Purpose: Consuming even low numbers of the foodborne pathogen, Listeria monocytogenes, places the elderly at risk for severe illness. e impact of immunomodulation on the development of listerial infection within a young and aged population a er low dose challenge with L. monocytogenes was investigated.Methods: Animals received daily supplementation of vitamin E for a period of 21 days to promote immunomodulation, and were then orally challenged with 100 CFU of L. monocytogenes. Levels of CD8 + , CD4 + and CD3 + T cells were used as markers to determine the in uence of daily supplementation with vitamin E on immune response; the spleen and liver were harvested for microbiological analysis.Results: Higher numbers of animals became infected in control groups than in vitamin Etreated group. During the post-challenge period, vitamin E-treated aged animals showed faster CD8 + T cell proliferation than control aged animals. Conclusion:Daily supplementation with vitamin E was more bene cial in young compared with aged animals in mitigating listerial infection. Results suggest exposure to even low numbers of L. monocytogenes can result in infection in both healthy young and aged populations.

Animal models of listeriosis: a comparative review of the current state of the art and lessons learned

“…Wu et al [ 248 ] inoculated starved guinea pigs retired from breeding colonies (weighing approx. 1000 g) and starved younger guinea pigs (weighing 250-300 g) with 100 CFU of a L. monocytogenes serotype 4b strain via oral gavage.…”

“…1000 g) and starved younger guinea pigs (weighing 250-300 g) with 100 CFU of a L. monocytogenes serotype 4b strain via oral gavage. Overall, 15% (i.e., 6/39) of geriatric animals and 8% (3/37) of younger animals developed infection based on pathogen detection in the liver and spleen, but none of the animals succumbed to infection, and only occasional mild gastro-intestinal symptoms developed in any of the animals [ 248 ]. Treatment with vitamin E appeared to have a protective effect for both geriatric and younger animals [ 248 ].…”

“…Overall, 15% (i.e., 6/39) of geriatric animals and 8% (3/37) of younger animals developed infection based on pathogen detection in the liver and spleen, but none of the animals succumbed to infection, and only occasional mild gastro-intestinal symptoms developed in any of the animals [ 248 ]. Treatment with vitamin E appeared to have a protective effect for both geriatric and younger animals [ 248 ]. Similar results have also been described by Pang et al [ 21 ], who analyzed the impact of vitamin E on L. monocytogenes infection in approximately 2-year-old guinea pigs that had been retired from breeding colonies.…”