To study the potential involvement of the TLR5 receptor in the host defense against leptospires, we used a murine model of leptospirosis and compared the susceptibility of C57BL6/J (WT) mice versus tlr5 knock-out (TLR5ko) mice after intraperitoneal infection with a sublethal dose of 107L. This evidence concerns the gene TLR5 and infection.