Genomic relatedness of the new matlab variants of Vibrio cholerae O1 to the classical and E1 Tor biotypes as determined by pulsed-field gel electrophoresis

The genomes of the recently described Matlab variants of Vibrio cholerae O1 that are hybrids between classical and E1 Tor biotypes were compared with those of E1 Tor and classical biotypes by the use of pulsed-field gel electrophoresis. Dendrograms constructed using the unweighted-pair group method using average linkages generated from NotI restriction patterns of whole-chromosomal DNA grouped these strains into two major clusters that were found to be similar but not identical to those of either of the biotypes. Strains that clustered with the classical biotype appear to have been derived from the classical strains, which are thought to be extinct.