Figure 2.

Location of the deletion within the RTX gene cluster of V. cholerae O395. (A) The chromosomal region of V. cholerae N16961 containing the RTX element is presented schematically. The ORFs within the region are represented by open arrows and labeled with the names of the genes they are predicted to encode. A line above the arrows provides a scale with the length indicated in kb. The extent of the deletion within the O395 RTX region is marked (↔). The ΔattRS1 deletion in the candidate vaccine strains has also been indicated. A line below the ORF map shows the position of EcoRV sites within the region, with the predicted fragment sizes produced by an EcoRV digest indicated in kb. Beneath this line are solid bars that represent the different DNA fragments cloned and used in this study and a set of small arrowheads that correspond to sites where different primers anneal. (B) Autoradiograph showing the Southern blot analysis of V. cholerae genomic DNA digested with EcoRV and hybridized with pRDA-S-15 probe. 569B, O395, and CA401 are of O1 serotype and classical biotype; N16961, Lou15, and C6709 are O1 serotype and El Tor biotype; and MO10 is an O139 serotype strain.