A type-specific antigen of Eikenella corrodens is the major outer membrane protein.

Eikenella corrodens released antigenic material in the form of outer membrane fragments during growth. A culture filtrate antigen (AgA) from three strains reacted with antisera to whole bacteria with serotype specificity. A monoclonal antibody to the AgA of strain 1073 reacted with only 2 of 12 strains tested by enzyme-linked immunosorbent assay, immunofluorescence assay, and immunoelectrophoresis assay. The antigenic reactivity was resistant to boiling and to pronase and trypsin treatments. AgA was isolated from an outer membrane preparation after boiling in sodium dodecyl sulfate, radioiodinating the proteins, and precipitating AgA specifically with monoclonal antibody. A single protein band corresponding to the major outer membrane protein of E. corrodens was observed by autoradiography of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the immunoprecipitate. AgA had a molecular weight of 42,000, and its amino acid content resembled those reported for major outer membrane proteins with similar molecular weights from two other gram-negative organisms.