Indirect CD4 + T cell protection against persistent MCMV infection by NK cells requires IFNγ.

Host control of mouse cytomegalovirus (MCMV) infection of MHCII ^- salivary gland acinar cells is mediated by CD4 ⁺ T cells, but how they protect is unclear. Here, we show CD4 ⁺ T cells control MCMV indirectly in the salivary gland, via IFNγ engagement with uninfected, but antigen ⁺ MHCII ⁺ APC and recruitment of NK cells to infected cell foci. This immune mechanism renders direct contact of CD4 ⁺ T cells with infected cells unnecessary and may represent a host strategy to overcome viral immune evasion.