To assess the impact of CD30 and OX40 deficiency on the effector CD4 T cell response, GS and GS CD30−/− × OX40−/− mice were assessed at 7 days post infection (dpi) with Lm-2W1S, revealing a substantial CD44hi 2W1S-specifc CD4 T cell population in both mouse strains, with the absence of CD30 and OX40 resulting in an approximate 2-fold reduction in total Ag-specific CD4 T cells (Fig. 1a, b). This evidence concerns the gene CD4 and infection.