Characterization of a 20-kDa pilus protein expressed by a diarrheogenic strain of non-O1/non-O139 Vibrio cholerae.

A diarrheogenic strain of non-O1/non-O139 Vibrio cholerae (10,325) belonging to serogroup O34 was earlier shown to express a new type of pilus composed of a 20-kDa subunit protein. Amino-terminal sequence data (determined up to 20 amino acid residues) of this protein showed it to be different from the subunit proteins of other known types of pili of V. cholerae. On the other hand, it showed complete homology with the corresponding sequence of a 22-kDa outer membrane protein (OmpW) of V. cholerae. Expression of 10,325 pili was favored in AKI rather than in NB medium and at 30 degrees C rather than at 37 degrees C. Further, cultural conditions favoring pilus expression also enhanced autoagglutination and adherence properties of strain 10,325. An antiserum to the 20-kDa protein induced passive protection against challenge with the parent organism 10,325, but not against V. cholerae O1 strains. Such protection was shown to be mediated by inhibition of intestinal colonization in vivo.