title: Outer membrane protein X (Ail) contributes to Yersinia pestis virulence in pneumonic plague and its activity is dependent on the lipopolysaccharide core length.
abstract: Yersinia pestis, the causative agent of plague, is one of the most virulent microorganisms known. The outer membrane protein X (OmpX) in Y. pestis KIM is required for efficient bacterial adherence to and internalization by cultured HEp-2 cells and confers resistance to human serum. Here, we tested the contribution of OmpX to disease progression in the fully virulent Y. pestis CO92 strain by engineering a deletion mutant and comparing its ability in mediating pneumonic plague to that of the wild type in two animal models. The deletion of OmpX delayed the time to death up to 48 h in a mouse model and completely attenuated virulence in a rat model of disease. All rats challenged with 1 × 10(8) CFU of the ompX mutant survived, compared to the 50% lethal dose (LD50) of 1.2 × 10(3) CFU for the wild-type strain. Because murine serum is not bactericidal for the ompX mutant, the mechanism underlying the delay in time to death in mice was attributed to loss of adhesion/internalization properties but not serum resistance. The rat model, which is most similar to humans, highlighted the critical role of serum resistance in disease. To resolve conflicting evidence for the role of Y. pestis lipopolysaccharide (LPS) and OmpX in serum resistance, ompX was cloned into Escherichia coli D21 and three isogenic derivatives engineered to have progressively truncated LPS core saccharides. OmpX-mediated serum resistance, adhesiveness, and invasiveness, although dependent on LPS core length, displayed these functions in E. coli, independently of other Yersinia proteins and/or LPS. Also, autoaggregation was required for efficient OmpX-mediated adhesiveness and internalization but not serum resistance.
authors.affiliation: Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, Idaho 83844-3052, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Kolodziejek
authors.forename: Darren R
authors.initials: DR
authors.lastname: Schnider
authors.forename: Harold N
authors.initials: HN
authors.lastname: Rohde
authors.forename: Andrzej J
authors.initials: AJ
authors.lastname: Wojtowicz
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Bohach
authors.forename: Scott A
authors.initials: SA
authors.lastname: Minnich
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Hovde
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008070:Lipopolysaccharides / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D010930:Plague / Q000382:microbiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017384:Sequence Deletion; D037521:Virulence Factors / Q000502:physiology*; D015010:Yersinia pestis / Q000472:pathogenicity* / Q000502:physiology
chemical_list: C526543:Ail protein, Yersinia pestis; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; D037521:Virulence Factors