Antigen-Specific Cell Mediated Immune Response to Chlamydia Trachomatis

With more than 90 million new cases annually, Chlamydia trachomatis is the most common sexually transmitted bacterial disease. Untreated endocervical C. trachomatis infections can cause pelvic inflammatory disease (PID), a disorder of the endometrium, fallopian tubes, and adjacent structures that occurs after ascension of the bacterium from the lower to upper genital tract. Adverse outcomes secondary to C. trachomatis-induced PID include tubal infertility, ectopic pregnancy, and chronic pelvic pain. Vaccine development has been identified as essential for control of C. trachomatis infections, and current evidence suggests that an effective vaccine will likely be based on several C. trachomatis antigens. Experimental models of infection have identified HSP60, major outer-membrane protein (MOMP), outer membrane protein 2 (OMP2), and polymorphic membrane protein D (PmpD) as promising vaccine candidates. A prospective study of Kenyan commercial sex workers found that production of interferon-gamma (IFN-γ) by peripheral blood cells stimulated with chlamydia heat-shock protein (HSP60) strongly correlated with protection against incident C. trachomatis infection. This proposal details an exploratory identification of the antigen-specific cell mediated immune responses associated with antecedent C. trachomatis infection in women. C. trachomatis is an obligate, intracellular, gram-negative microorganism recognized as the most common bacterial sexually transmitted disease worldwide. The highest rates of infection with this organism are consistently found among adolescents and young adults. Young women are also the group most adversely impacted by the effects of C. trachomatis infection on reproductive health. While approximately 70% of infections with C. trachomatis in young women are asymptomatic, 20% - 40% of these occult infections will progress from endocervical inflammation to the development of PID. In addition to its strong association with PID, C. trachomatis infection is also thought to enhance HIV transmission and contribute to human papilloma virus induced cervical neoplasia. Although data from both experimental models and clinical studies suggest that antigen specific CD4+ and CD8+ T cells are required for optimal control of genital tract chlamydial infections, the current lack of information regarding the specific C. trachomatis antigens eliciting protective immune responses in humans hinders vaccine development. This is an exploratory investigation in which we will develop the methodology needed to identify the antigen-specific cell mediated immune responses most strongly associated with protection against incident C. trachomatis infection.