Serological Identification of Pilus Antigen and Other Protein Antigens of Bacteroides nodosus Using Electro-Blot Radioimmunoassay after Electrophoretic Fractionation of the Proteins on Sodium Dodecyl Sulfate Polyacrylamide Gels

Proteins of various strains of B. nodosus were fractionated by polyacrylamide gel electrophoresis in buffer containing sodium dodecyl sulfate. Transfer of these proteins to activated paper was carried out electrophoreticaIly (Electro-Blot). Subsequent sequential reaction of these proteins with sera from sheep which had been naturally infected with a particular strain of B. nodosus showed that there were antibodies to many (10-15) components. Antibodies to pilus proteins could be recognized but the most predominant antibody in natural infections was to antigens in the region of molecular weight approximately 75000. Assessment of the paper-bound antigens by successive reactions with antisera from sheep infected with other strains of B. nodosus gave a semiquantitative picture of cross-reactions.