Purification and characterization of the CS2 pili of colonization factor antigen II produced by human enterotoxigenic Escherichia coli.

A subtype (CS2) of the colonization factor antigen II (CFA/II) of human enterotoxigenic Escherichia coli (ETEC) was studied. Analysis revealed that CS2-possessing ETEC was predominant among isolates from traveller's diarrhea at Osaka, Japan. TH61 pili produced by a clinical strain (TH61) were purified as a native form to homogeneity by zone electrophoresis and successive column chromatographies on Sepharose 4B and Phenyl-Sepharose CL-4B. It was demonstrated by immunogold staining technique and bacterial agglutination test that antisera against the purified pili of strain TH61 recognized pili of both strain TH61 and strain #C91f, a control strain possessing only CS2 pili. This suggests that TH61 pili purified in this study are CS2 pili. Subunit (pilin) of the purified pili has a molecular weight of about 16,000. Strains bearing CS2 could attach to human jejunal epithelial cells, and this attachment was inhibited by pretreating the enterocytes with purified pili. These indicate that CS2 pili are a factor responsible for attachment of ETEC bearing CS2 to human intestinal cells.