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Title: ELECTROPHORETIC ANALYSIS OF THE MAJOR OUTER MEMBRANE PROTEIN OF CHLAMYDIA PSITTACI REVEALS MULTIMERS WHICH ARE RECOGNIZED BY PROTECTIVE MONOCLONAL ANTIBODIES

Author
item MCCAFFERTY MICHA - MOREDUN RES. EDINBURGH,UK
item HERRING ALAN J - MOREDUN RES. EDINBURGH,UK
item ANDERSEN, ARTHUR
item JONES GARETH E - MOREDUN RES. EDINBURGH,UK

Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: The purpose of the research was to determine the chlamydial proteins of an ovine abortion strain of C. psittaci that neutralizing monoclonal antibodies (MAbs) reacted with. When chlamydial proteins were extracted with detergents and dithiothreitol without heating, a protein of 100 kDa was found that retained activity with the neutralizing MAbs. This protein when extracted using standard procedures and heating yeilded a protein of 38 kDa. The 38 kDa protein reacted with MAbs to the major outer membrane protein (MOMP) but not with the neutralizing MAbs. The results indicate that neutralizing MAbs are to a conformational epitope formed by a trimer of the MOMP.

Technical Abstract: The major outer membrane protein (MOMP) of the S26/3 ovine abortion strain of Chlamydia psittaci was purified from elementary bodies in soluble form by differential extraction with detergents and dithiothreitol. Electrophoretic analysis of unheated samples in SDS polyacrylamide gels gave an apparent molecular weight for MOMP of 100 kDa, almost three times the molecular weight observed for MOMP as a heat-denatured SDS peptide. Estimates of the sedimentation coefficient for the unheated form of MOMP were very similar to that of bacterial porin trimers. Immunoblotting experiments were performed with two monoclonal antibodies, previously shown to protect mice passively against chlamydial infection. These antibodies did not recognize the monomeric, denatured from of MOMP, but they bound strongly to the proposed trimer, indicating their specificity for the native configuration of the molecule.