Intranasal administration of chlamydial outer protein N (CopN) induces protection against pulmonary Chlamydia pneumoniae infection in a mouse model

Chlamydia pneunioniae is an intracellular pathogen that grows inside a vacuole, referred to as an inclusion. C. pnetanoniae possess a type III secretion system (TTSS), which allows them to secrete effector molecules into the inclusion membrane and to the host cell cytosol. Proteins such as chlamyclial outer protein N (CopN) that associate with the inclusion membrane are potential targets for the host's MHC-dependent antigen presentation. thereby representing ideal antigen candidates for T cell-based vaccination. The results of this study showed that intranasal immunization of BALB/c mice with heat-aggregated CopN protein and an Escherichia coli heat-labile toxin (LT) induced a strong immune response. detected as antigen-specific antibody production, lymphocyte proliferation and IFN-gamma production. Furthermore, the immunization induced statistically significant protection against intranasal C. pneunioniae challenge, the level of which correlated with the magnitude of CopN-specific lymphocyte proliferation. Both heat-aggregation of the antigen and the presence of LT adjuvant were required for maximal protective effect. (c) 2006 Elsevier Ltd. All rights reserved.