pseudotuberculosis. As G. mellonella possesses an innate immune system with structural and functional similarities to the mammalian innate immune system, it is a useful alternative to the traditional murine yersiniosis infection model, to examine virulence in vivo,

especially as unlike the C. elegans model, G. mellonella can be incubated at 37°C [42, 54]. Previous studies with Y. pseudotuberculosis comparing G. mellonella and the murine model, showed that G. mellonella could reflect infection in mammals and therefore could be useful as a check details higher throughput screen of mutants, before a more in depth analysis was undertaken in the murine model [42]. In this study the G. mellonella model demonstrated a role for Ifp in the pathogenesis of Y. pseudotuberculosis, in particular in concert with invasin, as the double mutant showed a significant increase in survival compared to the wild type (Figure 7). There also appeared to be mild attenuation in virulence

with both of the single mutants. This suggests that Ifp, together with invasin, does have a role in virulence of Y. pseudotuberculosis in this infection model. Conclusions We have shown the presence of a novel functional adhesin in Y. pseudotuberculosis that has been mutated with an IS element and is presumably non-functional in Y. pestis. Ifp is expressed during late log to early stationary phase at 37°C and demonstrates an ability to bind to HEp-2 cells in vitro, which can be disrupted by mutation of the gene, or even a single cysteine residue. Together

with invasin and intimin, Ifp is a new member of a family of outer membrane adhesins that is activated at 37°C and may act at a later stage than invasin during infection. Selleckchem MK-2206 Acknowledgements We are grateful to G. Frankel, Imperial College, London, UK for the intimin advice; E. Carniel, Institut Pasteur, Paris, France for the Y. pseudotuberculosis strain IP32953 and the pKOBEG vector; A. Darwin, NYU School of Medicine, New York, USA for the pAJD434 plasmid; and R. Isberg, Tufts University, Boston, USA Methocarbamol for the gift of the anti-invasin monoclonal antibody. We thank DSTL for financial support for this project. Electronic supplementary material Additional file 1: Amino acid alignment of Ifp from the four currently sequenced genomes of Y. pseudotuberculosis. Utilising the ClustalW program, the amino acid sequences of Y. pseudotuberculosis strains IP32953, IP31758, PB1 and YPIII were aligned. (DOC 38 KB) Additional file 2: Growth curves from the temporal expression of Ifp and invasin assay. Within the Anthos Lucy1 combined photometer and luminometer, OD readings at 600 nm were taken at 30 minute intervals and used to construct these growth curves. Cultures were incubated at (A) 24°C (B) 28°C and (C) 37°C. (PPT 96 KB) References 1. Achtman M, Zurth K, Morelli G, Torrea G, Guiyoule A, Carniel E: Yersinia pestis , the cause of plague, is a recently emerged clone of Yersinia pseudotuberculosis . Proc Natl Acad Sci USA 1999,96(24):14043–14048.