Public Library of Science, PLoS Pathogens, 10(17), p. e1010004, 2021
DOI: 10.1371/journal.ppat.1010004
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WhileSalmonella entericais seen as an archetypal facultative intracellular bacterial pathogen where protection is mediated by CD4+T cells, identifying circulating protective cells has proved very difficult, inhibiting steps to identify key antigen specificities. Exploiting a mouse model of vaccination, we show that the spleens of C57BL/6 mice vaccinated with live-attenuatedSalmonellaserovar Typhimurium (S. Typhimurium) strains carried a pool of IFN-γ+CD4+T cells that could adoptively transfer protection, but only transiently. CirculatingSalmonella-reactive CD4+T cells expressed the liver-homing chemokine receptor CXCR6, accumulated over time in the liver and assumed phenotypic characteristics associated with tissue-associated T cells. Liver memory CD4+T cells showed TCR selection bias and their accumulation in the liver could be inhibited by blocking CXCL16. These data showed that the circulation of CD4+T cells mediating immunity toSalmonellais limited to a brief window after whichSalmonella-specific CD4+T cells migrate to peripheral tissues. Our observations highlight the importance of triggering tissue-specific immunity against systemic infections.