Impact of Horizontal Gene Transfer on the Evolution of Salmonella Pathogenesis

Phage mediated horizontal transfer of the sopE1 gene increases enteropathogenicity of Salmonella enterica serotype Typhimurium for calves

“…Horizontal gene transfer has been proposed to be a major driving force in the evolution of virulence in the genus Salmonella. The phylogenetic distribution of Salmonella pathogenicity island 1 (SPI1), which encodes the invasion-associated type III secretion system, suggests that this virulence factor was acquired by a common ancestor of the genus Salmonella after its divergence from the Escherichia coli lineage [1]. The type III secretion system encoded by SPI1 is the prime virulence factor of Salmonella Typhimurium for the pathogenesis of diarrheal disease in cattle [2].…”

“…The type III secretion system encoded by SPI1 is the prime virulence factor of Salmonella Typhimurium for the pathogenesis of diarrheal disease in cattle [2]. It has therefore been proposed that acquisition of SPI1 was a key event during the evolution of enterocolitis, the disease syndrome caused the vast majority of Salmonella serotypes in man [1]. However, it is dif-¢cult to test this hypothesis experimentally since we can-not reconstruct events that led to acquisition of SPI1 by a common ancestor of the genus Salmonella some 50 to 100 million years ago.…”