A type 6 secretion system (T6SS) encoded gene within Salmonella enterica serovar Enteritidis contributes to virulence.

Bacteria interact with their host through protein secretion systems and surface structures. Pathogenic bacteria encode protein secretion systems that promote the invasion of the host's tissue, the evasion of the host's immune response, the thwarting microbial competitors, and ultimately survival within the host. For motile bacteria, the presence of extracellular flagella provides the host with a structural motif used for activation of the immune system. Within this issue of Virulence, the article "Identification of a novel gene in ROD9 island of Salmonella Enteritidis involved in the alteration of virulence-associated protein expression" describes the contribution of a gene, SEN1005, toward host-pathogen interaction. The authors demonstrate the contribution of SEN1005 to cell culture bioassays and infection in a mouse model of colitis. In each tested scenario, deletion of SEN1005 results in a phenotypic defect that was complemented by providing the SEN1005 gene in trans. SEN1005 contributes to the expression of known virulence factors within SPI-1, flagellar and chemotaxis genes, and heat shock/chaperone genes. Although much work is needed to fully elucidate the function of SEN1005, this work contributes toward our understanding of the genetic factors used by Salmonella to cause foodborne illnesses.