In fact, the most important immune mechanism for chlamydia clearance is IFN-γ, as T-bet deficient mice could not control chlamydia growth, but T cells shifted to a more Th17 response, whereas IFN-γ or IFN-γ-receptor deficient mice die from systemic infection (349, 350). This evidence concerns the gene IFNG and chlamydia trachomatis infectious disease.