WORKSHOP ON IN-VITRO NEUTRALIZATION OF CHLAMYDIA-TRACHOMATIS - SUMMARY OF PROCEEDINGS

A task force evaluated an in vitro antibody-mediated chlamydial neutra lization assay for its utility as a method to assess functional correl ates of antibody responses to Chlamydia trachomatis. Two monoclonal an tibodies that recognize different major outer membrane protein (MOMP) epitopes for a C. trachomatis serovar B strain exhibit good in vitro n eutralizing activity, with a maximum of 90% neutralization. Calculatio ns based on the 50% neutralization point indicated that 100% neutraliz ation could theoretically be achieved when only 10% of the MOMP molecu les bound antibody. Monoclonal antibodies that recognized either a het erologous MOMP or the genus-specific chlamydial lipopolysaccharide did not produce neutralizing activity. The standardized assay will be use ful to establish if in vitro neutralizing antibody responses are predi ctive of protective immunity and will aid in defining chlamydial antig ens and epitopes that may be attractive vaccine candidates.