Early translocation of acid-adapted Listeria monocytogenes during enteric infection in TNF/LTalpha-/- mice.

TNF/LTalpha deficient mice are devoid of Peyer's patches and lack mesenteric lymph nodes. Translocation, especially in the early steps after intragastric delivery of Listeria monocytogenes, has been explored in this study, and the role of TNFalpha has been addressed. We showed that L. monocytogenes translocation occurred at least as efficiently in TNF/LTalpha-/- mice as in TNF/LTalpha+/+ littermates. Even very low inocula (2.7x10(4) cfu) could initiate infection in the TNF/LTalpha deficient mice. Early kinetics of dissemination to the spleen and liver were similar, L. monocytogenes reaching these organs at 8 h post inoculation. However, a 10-fold higher bacterial load was observed at this early time point in the TNF/LTalpha deficient mice. rTNF pretreatment (4 h before intragastric inoculation) had no effect on the L. monocytogenes associated with the caecum-colon walls at 10 h after inoculation, although bacterial levels in the caecum-colon lumen and in spleen and liver were already controlled.