Natural infection induces partial immunity to Chlamydia trachomatis Identification of chlamydial antigens that induce interferon-γ secretion by T cells of immune women could advance vaccine development.
Interferon-γ production by CD4 and CD8 peripheral blood T cells from 58 high-risk women was measured after co-culture with antigen presenting cells preincubated with recombinant Escherichia coli expressing a panel of 275 chlamydial antigens. Quantile median regression analysis compared frequencies of IFN-γ responses in women with only cervical infection to women with endometrial infection; and in women who remained uninfected over a year to women who developed incident infection. Statistical methods were then used to identify proteins associated with protection.
A higher median frequency of CD8 responses was detected in Cervix+ compared to Endo+ (13.8% vs. 9.5%, P=0.04), but the CD4 response frequencies were not different. Women who remained uninfected displayed a greater frequency of positive CD4 responses (29% vs. 18%, P<0.0001) when compared to women with incident infection, while their frequencies of CD8 responses did not differ. A subset of proteins involved in central metabolism, type III secretion, and protein synthesis were associated with protection. CONCLUSIONS
Investigations in naturally exposed women reveal protective responses and identify chlamydial vaccine candidate antigens.