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Parenteral immunization with either formalin‐fixed whole cells of the fimbriate Bgd17 strain or purified fimbriae protected against Vibrio choleraeO1 infection in rabbits, independent of biotype and serotype. Parenteral immunization of adult rabbits with purified fimbriae prior to V. choleraeO1 challenge resulted in a reduction of 2 to 3 orders of magnitude in the number of bacteria recovered from the small intestines of immunized rabbits in comparison to non‐immunized controls. IgG and IgA antibodies against fimbrillin of V. choleraeO1 were detected in the convalescent sera of patients with cholera; however, little fimbrial antigen was detected in the commercially available cholera vaccines when examined by polyclonal and monoclonal antibodies against fimbriae. These data suggest that fimbrial hemagglutinin is a major adhesin of V. choleraeO1 and that parenteral immunization with fimbriae generates a specific immune response in the gut that may serve as one means of mitigating subsequent V. choleraeO1 gut infection.

We have analyzed our collection of Vibrio choleraeO139 strains to determine whether filamentous phages are produced in their culture supernatants, and whether any replicative form of DNA is detectable in cell lysates. Two types of filamentous phage, designated fs1 (6.4 kb) and fs2 (8.5 kb), were found in strains of Vibrio choleraeO139, fs1 was commonly produced from clinical isolates of Vibrio choleraeO1. Infectious particles (filamentous phages) were inducible by subculture, mitomycin C, and cultivation in a ligated ileal loop of a rabbit. Type 4 fimbriae of Vibrio choleraeO1 sensitive to d‐glucose and d‐mannose were suggested to be receptors for fs1 and fs2. The genome of fs1 was revealed to encode a potential new enterotoxin homologous to zonula occludens toxin. Clarification of the relation of type 4 fimbriae and these filamentous phages will provide a new understanding of the colonization of Vibrio choleraeO1 and O139. Thus the presence of a new enterotoxin encoded by the genome of filamentous phage like fs1 may clarify the pathogenesis of cholera toxin negative clinical isolates of Vibrio choleraeO1 and non‐O1. Our findings combined with the earlier report by Ehara et al. [Microbio. Immunol. 37 (1993) 679–688] suggest that type 4 fimbriae of Vibrio choleraeO1 are important for the development of an effective vaccine against cholera.

We have analyzed our collection of Vibrio cholerae O139 strains to determine whether filamentous phages are produced in their culture supernatants, and whether any replicative form of DNA is detectable in cell lysates. Two types of filamentous phage, designated fs1 (6.4 kb) and fs2 (8.5 kb), were found in strains of Vibrio cholerae O139, fs1 was commonly produced from clinical isolates of Vibrio cholerae O1. Infectious particles (filamentous phages) were inducible by subculture, mitomycin C, and cultivation in a ligated ileal loop of a rabbit. Type 4 fimbriae of Vibrio cholerae O1 sensitive to d-glucose and d-mannose were suggested to be receptors for fs1 and fs2. The genome of fs1 was revealed to encode a potential new enterotoxin homologous to zonula occludens toxin. Clarification of the relation of type 4 fimbriae and these filamentous phages will provide a new understanding of the colonization of Vibrio cholerae O1 and O139. Thus the presence of a new enterotoxin encoded by the genome of filamentous phage like fs1 may clarify the pathogenesis of cholera toxin negative clinical isolates of Vibrio cholerae O1 and non-O1. Our findings combined with the earlier report by Ehara et al. [Microbio. Immunol. 37 (1993) 679–688] suggest that type 4 fimbriae of Vibrio cholerae O1 are important for the development of an effective vaccine against cholera.