FIG 2.

MHC-II tetramers reveal that RVFV-specific CD4 T cells in the liver and spleen are Th1 and Tfh focused. Two MHC-II tetramers (AYQ and VRE) with the same core epitope identified RVFV-specific CD4 T cells from the spleen of an infected mouse, while a control tetramer (PVS) was negative (A). The MHC-II VRE tetramer was used to quantitate the frequency and number of virus-specific CD4 T cells in various tissues following DelNSs RVFV infection (B). Each symbol represents one mouse. Liver mononuclear cells and splenocytes isolated 7 days postinfection with DelNSs RVFV were stimulated ex vivo with PMA/ionomycin, followed by staining with IL-13, IFN-γ, CXCR5, and FoxP3. VRE⁺ CD4 T cells from both the liver and the spleen were identified as largely Th1 and Tfh subtypes. Phenotyping of total CD4 T cells is shown for comparison.