TLR9 and infection: To investigate the involvement of AEP and cysteine proteases such as CatB, L and S on the development of cutaneous lesions following infection with L. major, we compared the footpad thickness between WT, AEP-/-, CatB-/-, CatL-/-, CatS-/- and TLR9-/- mice over a time-course of 49 days.