The results in the present study suggest that CCL5 is required for optimal Th1 cellular responses against and clearance of Chlamydia. These results corroborate our previous findings that CCR5-dependent mucosal immune responses are required for the efficient clearance of genital chlamydial infection, while functional CCR5 expression reduces infertility as a pathologic consequence of Th1-mediated inflammation associated with infection [22]. This evidence concerns the gene CCR5 and infection.