On day 5 post Cl-13 infection, IFNARfl/fl x Foxp3YFP-Cre mice had reduced frequencies and numbers of CD8+CD44+NP396 Tet+ cells, and in addition GP33- and GP276-stimulated CD8+CD44+ T cells from IFNARfl/fl x Foxp3YFP-Cre infected mice produced significantly less Granzyme B (GrB) positive and GrB/IFN-γ double positive cells compared to CD8+ T cells from control mice (Fig 5F and 5G), however IFN-γ positive cells are tended to be more in infected IFNARfl/fl x Foxp3YFP-Cre mice but they are not significant compared to control mice. The gene discussed is CD8A; the disease is infection.