Saoirse Walsh (Berlin / DE), Antje-Maria Lapschies (Berlin / DE), Mathias Müsken (Brunswick / DE), Manfred Rohde (Brunswick / DE), Simone Bergmann (Brunswick / DE), Marcus Fulde (Berlin / DE)
Introduction
Streptococcus canis is a Lancefield group-G opportunistic pathogen that colonises the mucosal surfaces and skin of the host, predominantly affecting cats and dogs. S. canis is a zoonotic pathogen with human infections being observed more recently, mainly caused by contact with companion animals.
Different virulence factors, e.g. proteases, enable colonization, survival and replication during pathogenesis of streptococci. In silico analysis has shown that the IgG-specific protease of S. canis termed IdeC is a secreted protein containing a signal sequence but no membrane anchor. IdeC is suggested to act with a similar mechanism to the IdeS protein of Streptococcus pyogenes, a secreted cysteine kinase that cleaves the IgG molecule between the hinge and CH2 region. The IdeC protein also has an Arg-Gly-Asp (RGD) motif, an important integrin binding motif. Bacterial proteins containing RGD motifs have been implicated in adhesion and invasion of host cells. This along with the ability of IdeC to bind back to the bacterial surface after secretion suggest a possible second function of IdeC in adhesion.
Goals
This project is focused on elucidating the functional role of the S. canis protein IdeC. Specifically, what role this protein may play in mediating host-pathogen interactions.
Materials & Methods
Fluorescent latex beads coated in recombinant IdeC protein are used to assess the interaction of IdeC with epithelial and endothelial cells. Further, a recombinant protein with RGD replaced with RGE has been produced to test the role of the motif in any interaction observed.
Results
Based on fluorescence microscopy analysis, IdeC coated latex beads displayed increased interaction with both epithelial and endothelial cells when compared to IdeC_RGE and BSA controls. Electron microscopy indicates that IdeC coated beads may be internalised however, a mechanism is yet to be determined.
Summary
Here we present evidence that the streptococcal protein IdeC may have a second function, involving bacterial attachment and invasion into host cells during infection.