Staphylococcal defence against innate immunity 
(Seminars)
8 May 2012
3.30pm
Venue: Room 501.505, Level 5, Building 501, Faculty of Medical and Health Sciences, Grafton Campus
Contact info: Robyn McDonald
Contact email: r.mcdonald@auckland.ac.nz
Department of Molecular Medicine and Pathology seminar by Professor John Fraser, Dean, Faculty of Medical and Health Sciences.
Staphylococcus aureus is a gram positive commensal bacterium carried in the noses of approximately 20% of healthy adults. S. aureus possesses an arsenal of virulence factors that promote survival in different niches and many of these factors are human specific indicating that the bug has co-evolved with primates. Our goal is to understand what constitutes an effective immune response to S. aureus and to identify those virulence factors that are most linked to disease. We identified the staphylococcal superantigen-like (SSL) factors, an almost contiguous cluster of 11 genes located in a very stable genomic island. We have studied the SSLs and found that, unlike their superantigenic cousins that stimulate T cells, the SSLs all target different steps in opsonophagolysis. As examples, SSL7 binds to human IgA and complement C5 to inhibit C5a and MAC formation. SSL10 binds hIgG1 to block Fcγ receptor and C1q mediated phagocytosis. SSL4 and 11 are examples of carbohydrate binding factors that enter myeloid cells to disrupt myeloid cell mobility and migration. The SSLs are tightly regulated and only expressed under conditions of stress suggesting that they are selectively produced in response to immune attack. Potential uses of the SSLs as targets for anti-staphylococcal treatment will be discussed.
