Major Outer Membrane Proteins: Common Antigens in Enterobacteriaceae Species

Abstract

The major membrane (OM) proteins of 23 enterobacterial strains (principally clinical isolates) and 5 non-Enterobacteriaceae species were investigated by the sodium dodecyl sulfate-polyacrylamide gel immunoperoxidase (SGIP) technique to evaluate antigenic cross-reactivity among these proteins. All enterobacterial strains contained 1 or more peptidoglycan-associated major OM proteins, cross-reactive with the peptidoglycan-bound protein I of Escherichia coli, and 1 non-peptidoglycan-bound heat-modifiable protein, cross-reactive with protein II* of E. coli. Antigenic cross-reactivity of the major OM proteins apparently is a general phenomenon in the family Enterobacteriaceae, independent of any MW variation of the corresponding proteins in different bacterial strains. SGIP experiments conducted with OM preparations of other species showed no cross-reactivity of any of their OM proteins with enterobacterial major OM proteins. The significance of the immunological relatedness of OM proteins for the classification of some Enterobacteriaceae is discussed.