[Structures and hemagglutinating functions of pili K99 with glucose-dependent or constitutive biosynthesis and of pili F41].

The K99 and F41 pili produced by most bovine enterotoxigenic Escherichia coli were composed of polypeptide subunits with molecular weights of 18,300 and 29,000. The glucose dependency of K99 pili biosynthesis in some strains of E. coli was evidenced by results of SDS-polyacrylamide gel electrophoresis. Differences in electrophoretic mobility in "Noble" agar between K99 pili from glucose-dependent and independent pathways were unrelated to differences in subunit molecular weight. The K99 and F41 pili displayed two kinds of mannose-resistant haemagglutination properties: 1) strong and thermostable; and 2) weaker than "1" and properties: 1) strong and thermostable; and 2) weaker than "1" and thermolabile. The reproducibility of results concerning "2" was poor and depended on the age of extracts and erythrocytes. It was therefore proposed that only "1" be retained, with sheep and guinea-pig erythrocytes for F41 pili and horse erythrocytes for K99 pili.