First, we showed that pigs develop a strong IFN-γ CD4+ T-cell response upon Ct or Cs infection [11]; second, the influx of CD4 T cells into the genital tract tissue has previously been shown to represent a good correlate of protection: Erneholm et al. showed in minipigs that cervical infiltration of CD4 T cells upon immunization with inactivated Ct + CAF01 adjuvant was associated with protection against genital Ct infection [20]. The gene discussed is CD4; the disease is infection.