Cross-reaction between a strain of Vibrio mimicus and V-cholerae O139 Bengal

Of 200 isolates of Vibrio mimicus screened, one from water (N-57) agglutina ted with V. cholerae O139 polyclonal antiserum (absorbed with a rough strai n of V. cholerae only) and not with O139 polyclonal diagnostic antiserum (a bsorbed with the rough strain and V. cholerae O22 and O155). The antigenic relationship between V. cholerae O139 and N-57 is of a,b-a,c type, where a is the common antigenic epitope and b and c are unique epitopes. Strain N-5 7 was assigned to a new serogroup of V. cholerae O194. It gave negative res ults in a monoclonal antibody-based rapid test and a PCR test specific for V. cholerae O139. It did not possess the ctx gene or produce cholera toxin. Antiserum to strain N-57 cross-protected infant mice against cholera on ch allenge with V. cholerae O139. Structural studies of the surface polysaccha rides and studies of the rfb genes will shed more light on the extent of re latedness between V. mimicus N-57 and V. cholerae O139.