In order to rule out the possibility of a defect in IFN-γ-mediated recruitment of an effector population in CD4-depleted IFN-γ−/− mice, IFN-γ−/− and μMT control mice were depleted of CD4+ T cells during primary infection (as shown in Fig. 1) and levels of immune cell populations present in the genital tract were determined by flow cytometry. This evidence concerns the gene CD4 and infection.