However, rECG vaccines have been shown to induce equal or even stronger immune responses than subunit vaccines without the addition of additional adjuvants, and they induce high levels of Th1-related IgG2a antibody and IFN-γ and genital tract-soluble IgA, which is also necessary for resistance to chlamydial infection (Eko et al., 2003). The gene discussed is IFNG; the disease is chlamydia trachomatis infectious disease.