BIOCHEMICAL AND SEROLOGICAL CHARACTERIZATION OF ESCHERICHIA-COLI FIMBRIAL ANTIGEN-F165(2)

Mannose-resistant hemagglutinating fimbrial antigen F165 is produced by Escherichia coli strains associated with septicemia in piglets and calves. A fimbrial component with an M(r) of 17 200 as determined by SDS-PAGE was purified to homogeneity from F165-positive E. coli strain 4787 of serogroup O115. This fimbrial component of F165 antigen was named F165(2). Separation procedures included fast protein liquid chromatography with a Superose 12 column followed by ultracentrifugation and 0.15 M ethanolamine buffer (pH 10.5) dissociation. Upon removal of ethanolamine, the fimbrial component reassociated into fimbriae. Amino acid composition analysis indicated that the fimbrial component molecule comprised 158 amino acid residues of which 37.3% were hydrophobic. The amino acid composition and the isoelectric point (9.5) were readily distinguishable from those of F1 fimbriae. The amino acid sequence was determined for approximately 40% of the molecule. For the first 33 residues, the F165(2) sequence was identical to that of FIB fimbriae and very similar to that of F1C. Fimbriae F165(2) could nevertheless be differentiated antigenically from F1C fimbriae as demonstrated by the immunodot technique using cross-absorbed antisera.