The evolutionary diversification of the toxin locus.

is a diverse species of bacterial pathogens comprised of >2,500 serovars with variable host ranges and virulence properties. Accumulating evidence indicates that two AB-type toxins, typhoid toxin and ArtAB toxin, contribute to the more severe virulence properties of the strains that encode them. It was recently discovered that there are two distinct types of -like genetic elements in : those that encode ArtAB toxins ( elements) and those in which the gene is degraded and the ArtB homolog, dubbed PltC, serves as an alternative delivery subunit for typhoid toxin ( elements).