Daskaleros, P.A., Payne, S.M. 1985.Cloning the gene for Congo red binding in Shigella flexneri. Infection & Immunity. 48(1):165-8.
The ability to bind the dye Congo red from agar medium is associated with virulence of Shigella species. DNA sequences conferring this property have been cloned from a large, 140-kilobase plasmid of Shigella flexneri into a plasmid vector. This recombinant plasmid does not fully restore virulence to S. flexneri isolates which have lost the large plasmid. This indicates that other genes present on the 140-kilobase plasmid must also be required for virulence of S. flexneri. The cloned fragment contains a copy of the insertion sequence IS1 closely linked to the gene for Congo red binding.
