PFGE profiles (left) of the genomic DNAs of V. cholerae strains belonging to different serogroups and biotypes digested with I-CeuI and schematic diagram (right) of dendrogram analysis of the strains. Lane 1, 94001 (O139; cholera toxin negative; China); lane 2, 1837 (O139; ctxAB+; Bangladesh); lane 3, MO45 (O139; ctxAB+; India); lane 4, 22s (O22; cholera toxin negative; China); lane 5, 86015 (O1; El Tor biotype; cholera toxin negative; China); lane 6, Bin-43 (O1; El Tor biotype; ctxAB+; China); lane 7, Wujiang-2 (O1; El Tor biotype; ctxAB+; China); lane 8, 1119 (O1; classical biotype; ctxAB+; India); lane 9, O395 (O1; classical biotype; ctxAB+; Bangladesh); lane 10, 569B (O1; classical biotype; ctxAB+; Bangladesh); lane M, λ DNA ladder molecular size standard.