Newly recruited intraepithelial Ly6A+CCR9+CD4+ T cells protect against enteric viral infection

Abstract

The intestinal epithelium comprises the body's largest surface exposed to viruses. Additionally, the gut epithelium hosts a large population of intraepithelial T lymphocytes, or IELs, although their role in resistance against viral infections remains elusive. By fate-mapping Tcells recruited to the murine intestine, we observed an accumulation of newly recruited CD4+ Tcells after infection with murine norovirus CR6 and adenovirus type-2 (AdV), but not reovirus. CR6- and AdV-recruited intraepithelial CD4+ Tcells co-expressed Ly6A and chemokine receptor CCR9, exhibited T helper 1 and cytotoxic profiles, and conferred protection against AdV invivo and in an organoid model in an IFN-γ-dependent manner. Ablation of the Tcell receptor (TCR) or the transcription factor ThPOK in CD4+ Tcells prior to AdV infection prevented viral control, while TCR ablation during infection did not impact viral clearance. These results uncover a protective role for intraepithelial Ly6A+CCR9+CD4+ Tcells against enteric adenovirus.