UDP-glucose hydrolases are a group of relatively little known membrane-bound or periplasmic enzymes found in Sal-monella enterica and E. coli. UDP-glucose is an agonist for a specific P2 receptor (P2Y14) found on epithelial cells and cells associated with innate immunity. It is also recognised as a 'danger signal'. Cells respond to mechanical damage by releasing UDP-glucose which activates P2Y14 to trigger an innate immune response; it is postulated that a similar re-sponse to bacterial infection may be protective against infection. However, the UDP-glucose hydrolases may constitute virulence factors able to abrogate this response by degradation of the released UDP-glucose.