Subunit vaccines for the prevention of mucosal infection with Chlamydia trachomatis

Abstract

Chlamydia trachomatis is the most common preventable cause of tubal infertility in women. In high-income countries, despite public health control efforts, C. trachomatis case rates continue to rise. Most medium and low-income countries lack any Chlamydia control program; therefore, a vaccine is essential for the control of Chlamydia infections. A rationally designed Chlamydia vaccine requires understanding of the immunological correlates of protective immunity, pathological responses to this mucosal pathogen, identification of optimal vaccine antigens and selection of suitable adjuvant delivery systems that engender protective immunity. Fortunately, Chlamydia vaccinology is facilitated by genomic knowledge and by murine models that reproduce many of the features of human C. trachomatis infection. This article reviews recent progress in these areas with a focus on subunit vaccine development.

Keywords: Chlamydia; adjuvant; antigen; immunoproteomics; tissue-resident memory T cells; vaccine.

Figure 1. Reproductive damage

Pelvic inflammatory disease in women caused by C. trachomatis (sites of infection shown) can result in tubal factor infertility, ectopic pregnancy, and chronic pelvic pain. Reproduced with permission from [37].

Figure 2. Two waves of vaccine-induced C. trachomatis-specific memory T cells

The first wave generated mucosal T cells which provided early protection and a second wave generated systemic T cells which augmented early and late protection. Mucosal immunization with adjuvant induced both the first and second waves of T cells. Systemic immunization induced only the second wave and generated incomplete protection. Reproduced with permission from [36].