Identification of protective epitopes by sequencing of the major outer membrane protein gene of a variant strain of Chlamydia psittaci serotype 1 (Chlamydophila abortus)

Protective monoclonal antibodies (MAbs) to the major outer membrane protein (MOMP) of species of the family Chlamydiaceae, which is the primary vaccin e candidate antigen, recognize nonlinear epitopes conferred by the oligomer ic conformation of the molecule. Protective MAbs failed to recognize oligom eric MOMP of the variant strain LLG, which bears amino acid substitutions i n variable segments (VSs) 1, 2, and 4, and competed with monomer-specific M Abs mapping to these VSs in reference strain 577. The results suggest that multiple sites located in the three VSs contribute to the epitope of protec tive MAbs.