CD4 and infection: CD103 has been observed on CD8 Trm cells.43 Its expression on CD4 T cells is still controversial, although some studies do report CD103 on CD4 Trm cells.44 Moreover, a recent study identified CD49d (α4) on CD4 T cells being recruited to the upper genital tract.45 CD69 has been observed on both CD4 and CD8 Trm cells.44 Our results showed that cells in the GT at day 50 post infection only expressed low levels of CD49d and CD103 (Fig. 5).