AN INTERMOLECULAR MECHANISM OF T-CELL HELP FOR THE PRODUCTION OF ANTIBODIES TO THE BACTERIAL PATHOGEN, CHLAMYDIA-TRACHOMATIS

Antibodies that neutralize infectivity are directed at the antigenical ly variant major outer membrane protein (MOMP) of Chlamydia trachomati s. A vaccine for chlamydia will need to include T cell determinants th at elicit T helper (Th) cells which provide help to MOMP-specific B ce lls. A limited number of determinants on MOMP are able to elicit Th ce lls and sequence diversity in the MOMP molecule may alter T cell recog nition of these determinants. We investigated whether two sequence inv ariant proteins of C trachomatis that are both abundant and immunogeni c could elicit T cell help for the production of antibody to MOMP We f ound that outer membrane protein 2 (OMP2) but not outer membrane prote in 3 (OMP3) was able to prime BALB/c mice for an anamnestic anti-MOMP response following boost with the intact organism. This demonstration of an intermolecular mechanism of T cell help in a bacterial system ha s important implications for the development of a chlamydial vaccine a s well as the design of vaccines for other antigenically variant non-v iral pathogens.