Partial characterization of an 89-kDa highly immunoreactive protein from Chlamydia psittaci A/22 causing ovine abortion.

An 89-kDa immunogen from Chlamydia psittaci A/22 causing ovine abortion was partially characterized. The 89-kDa protein, localized on the outer membrane complex of chlamydiae, was synthesized relatively early in the developmental cycle. The protein contained cysteine but was not extensively cross-linked by disulfide bonds. Treatment with proteases apparently did not cleave the protein. The infectivity of strain A/22 was partially (60%) reduced by treatment of chlamydial elementary bodies with monoclonal antibody BS/89 specifically reacting with the 89-kDa antigen. Species-specific as well as strain-specific antigenic determinants were present on the 89-kDa protein.