Chlamydia trachomatis antigen (C. trachomatis antigen)

Chlamydia trachomatis antigens are a diverse group of proteins and glycolipids expressed by the obligate intracellular bacterium Chlamydia trachomatis, which is the leading cause of bacterial sexually transmitted infections and infectious blindness worldwide (StatPearls, 2023). The Major Outer Membrane Protein (MOMP) is the most prominent antigen, functioning as a structural porin and the primary target for neutralizing antibodies (PMID: 29158414). Other critical antigens include Polymorphic Membrane Proteins (Pmps), which are essential for bacterial adhesion to host epithelial cells, and the Chlamydial Protease-like Activity Factor (CPAF), which facilitates immune evasion by degrading host transcription factors (PMID: 25231120, PMID: 24003140). These antigens are the primary targets for vaccine development, with candidates like CTH522 undergoing clinical trials to induce protective mucosal and systemic immunity (NCT02787109). In addition to vaccine development, these antigens serve as the basis for diagnostic tools, including direct fluorescent antibody (DFA) tests and enzyme-linked immunosorbent assays (ELISA) (CDC, 2021). The transition of the bacterium between its infectious elementary body (EB) and replicative reticulate body (RB) stages involves differential expression of these antigens, complicating the immune response (PMID: 30635460). Therapeutic strategies targeting these antigens aim to prevent severe complications such as pelvic inflammatory disease, ectopic pregnancy, and infertility (WHO, 2022).

Other names

Major outer membrane protein (MOMP)Polymorphic membrane proteins (Pmps)Chlamydial protease-like activity factor (CPAF)Outer membrane complex protein B (OmcB)Chlamydial heat shock protein 60 (cHSP60)60 kDa chaperoninPmpDOmpA

Induction of neutralizing antibodies and T-cell mediated immunity to prevent bacterial attachment, promote opsonization, and clear intracellular infection.