title: Gut proteases target Yersinia invasin in vivo.
abstract: BACKGROUND
  Yersinia enterocolitica is a common cause of food borne gastrointestinal disease. After oral uptake, yersiniae invade Peyer's patches of the distal ileum. This is accomplished by the binding of the Yersinia invasin to β1 integrins on the apical surface of M cells which overlie follicle associated lymphoid tissue. The gut represents a barrier that severely limits yersiniae from reaching deeper tissues such as Peyer's patches. We wondered if gut protease attack on invasion factors could contribute to the low number of yersiniae invading Peyer's patches.
  
  
  RESULTS
  Here we show that invasin is rapidly degraded in vivo by gut proteases in the mouse infection model. In vivo proteolytic degradation is due to proteolysis by several gut proteases such as trypsin, α-chymotrypsin, pancreatic elastase, and pepsin. Protease treated yersiniae are shown to be less invasive in a cell culture model. YadA, another surface adhesin is cleaved by similar concentrations of gut proteases but Myf was not cleaved, showing that not all surface proteins are equally susceptible to degradation by gut proteases.
  
  
  CONCLUSIONS
  We demonstrate that gut proteases target important Yersinia virulence factors such as invasin and YadA in vivo. Since invasin is completely degraded within 2-3 h after reaching the small intestine of mice, it is no longer available to mediate invasion of Peyer's patches.
authors.affiliation: Max von Pettenkofer Institut für Hygiene und Medizinische Mikrobiologie, Ludwig Maximilians Universität München, Germany. truelzsch@mvp.uni-muenchen.de.
authors.forename: Janja
authors.initials: J
authors.lastname: Trček
authors.forename: Marc F
authors.initials: MF
authors.lastname: Oellerich
authors.forename: Katy
authors.initials: K
authors.lastname: Niedung
authors.forename: Frank
authors.initials: F
authors.lastname: Ebel
authors.forename: Sandra
authors.initials: S
authors.lastname: Freund
authors.forename: Konrad
authors.initials: K
authors.lastname: Trülzsch