Antigenicity of Neisseria gonorrhoeae outer membrane protein(s) III detected by immunoprecipitation and Western blot transfer with a monoclonal antibody.

Some properties of gonococcal outer membrane III were studied by using a monoclonal antibody (2E6) in Western blot transfer and immunoprecipitation reactions. By Western blot, the 2E6 monoclonal had a single antigenic target: outer membrane protein III. All three gonococcal strains examined exhibited identical reactivities for their protein(s) III with this monoclonal. When 125I-labeled gonococci were incubated with monoclonal antibody 2E6, lysed in Zwittergent, and antibody-antigen complexes were immunoprecipitated with protein A-Sepharose, both outer membrane proteins I and III were present in the immunoprecipitates regardless of the gonococcal strain used. Exposure of gonococci to Iodogen and 2-mercaptoethanol influences the electrophoretic migration characteristics of protein(s) III in polyacrylamide gel electrophoresis with sodium dodecyl sulfate; the antigenicity of protein(s) III was unaltered when assessed by Western blot transfer after reaction with Iodogen or 2-mercaptoethanol. These data demonstrate that outer membrane protein III is a surface-exposed antigenic moiety common to diverse strains of gonococci.