TLR4 and infection: In this study, we used two serovars of pathogenic Leptospira, two strains of mice (C57BL/6 immunocompetent and immunocompromised C3H/HeJ with a mutation in TLR4) and two different techniques to monitor Leptospira dissemination after infection to determine if live Leptospira disseminates to and colonizes the testes.