Genomic and biochemical relatedness between Vibrio cholerae serovar O139 and serovar O1 eltor strains.

Vibrio cholerae O139 (Bengal) the new pandemic cholera strain emerging on the Indian subcontinent has revealed considerable homology to Vibrio cholerae O1 EL Tor (strain of the seventh pandemic cholera) in terms of genetic and biochemical properties. Apart from capsule and O139 LPS formation, all strains of V. cholerae O139 were found to be identical to V. cholerae O1 EL Tor strains with respect to genomic restriction fragment length polymorphism, genomic distribution of the pathogenic island, pattern of OMP and multilocus enzymes. However, the analysis of a nonpathogenic V. cholerae O139 isolate from Sri Lanka with a totally different pattern of genetic properties underline that horizontal gene transfer of a piece of DNA encoding biosynthesis of the Vibrio cholerae O139-specific LPS and capsule formation to an O1 El Tor precursor strains must have occurred giving rise to a kind of hybrid V. cholerae O1 El Tor encoding the new serovar-specific O139 antigens.