Staphylococcus aureus, a commensal of the human skin and nares, is also an invasive pathogen and frequent cause of skin and soft tissue infections, bacteremia and sepsis. Many clinical isolates are resistant against commonly used antibiotics and these strains are collectively referred to as methicillin-resistant S. aureus (MRSA). The annual survival rate of patients with MRSA sepsis is less than 50%. S. aureus is the only bacterial pathogen known to coagulate plasma and to agglutinate with fibrin cables in blood. We show here that this agglutination phenotype is based on the secreted products from three genes (coa, vwb, clfA) as well as several non-secreted gene products. We propose a new model whereby S. aureus agglutination involves the formation of staphylothrombin (Coa, vWbp)-assembled fibrin cables, which are capped by clumping factor A (ClfA) on the staphylococcal surface and crosslinked by factor XIII. We hypothesize that S. aureus agglutination provides for escape from phagocytic killing. Further, vWbp-mediated recruitment of von Willebrand Factor (vWF) provides a tether for endothelial cells and supports bacterial traffic out of the vasculature thereby promoting S. aureus dissemination to organ tissues where staphylococci replicate as a bacterial community, protected from immune cells. This key virulence strategy may be perturbed with monoclonal antibodies and small molecule inhibitors to either prevent or treat S. aureus sepsis. Preliminary work demonstrated that S. aureus Coa and vWbp each associate with host prothrombin to form multi-protein complexes in human plasma (with prothrombin, fibrinogen, fibronectin and factor XIII) dedicated to the formation of cross-linked fibrin cables. Staphylococcal agglutination involves the surface display of functional ClfA, which requires several gene products [aggABCD, (staphylococcal agglutination genes)] that appear to modify ClfA prior to sortase A-mediated anchoring in the bacterial cell wall envelope (srtA). In addition to genetic loss-of-function analysis, we will also reconstitute agglutination in vitro from purifie components and in vivo by expressing genes in Staphylococcus epidermidis, an opportunistic pathogen that cannot agglutinate or form discrete abscess lesions. Monoclonal antibodies (mAbs) -isolated against purified Coa, vWbp or ClfA- and small molecule inhibitors are being used to perturb staphylococcal agglutination in vitro and in vivo and examined for the provision of protection or therapy in a mouse model of S. aureus sepsis.
In 2012, S. aureus caused 90,000 cases of invasive disease with bacteremia or sepsis with an aggregate mortality of more than 19,000. Staphylococcal sepsis cannot be prevented with antibiotics alone due to the emergence of drug-resistant MRSA strains. This proposal seeks to characterize the molecular basis of staphylococcal agglutination, the strategy for S. aureus escape from phagocytosis during blood infection, and to develop therapeutic antibodies and small molecule inhibitors that block agglutination.
|Pigozzo, Alexandre B; Missiakas, Dominique; Alonso, Sergio et al. (2018) Development of a Computational Model of Abscess Formation. Front Microbiol 9:1355|
|Mancini, Stefano; Oechslin, Frank; Menzi, Carmen et al. (2018) Marginal role of von Willebrand factor-binding protein and coagulase in the initiation of endocarditis in rats with catheter-induced aortic vegetations. Virulence 9:1615-1624|
|Bobrovskyy, Maksym; Willing, Stephanie E; Schneewind, Olaf et al. (2018) EssH peptidoglycan hydrolase enables Staphylococcus aureus type VII secretion across the bacterial cell wall envelope. J Bacteriol :|
|Claes, J; Liesenborghs, L; Peetermans, M et al. (2017) Clumping factor A, von Willebrand factor-binding protein and von Willebrand factor anchor Staphylococcus aureus to the vessel wall. J Thromb Haemost 15:1009-1019|
|Ohr, Ryan Jay; Anderson, Mark; Shi, Miaomiao et al. (2017) EssD, a Nuclease Effector of the Staphylococcus aureus ESS Pathway. J Bacteriol 199:|
|Aly, Khaled A; Anderson, Mark; Ohr, Ryan Jay et al. (2017) Isolation of a Membrane Protein Complex for Type VII Secretion in Staphylococcus aureus. J Bacteriol 199:|
|Yu, Wenqi; Kim, Hwan Keun; Rauch, Sabine et al. (2017) Pathogenic conversion of coagulase-negative staphylococci. Microbes Infect 19:101-109|
|Anderson, Mark; Ohr, Ryan Jay; Aly, Khaled A et al. (2017) EssE Promotes Staphylococcus aureus ESS-Dependent Protein Secretion To Modify Host Immune Responses during Infection. J Bacteriol 199:|
|Thomer, Lena; Emolo, Carla; Thammavongsa, Vilasack et al. (2016) Antibodies against a secreted product of Staphylococcus aureus trigger phagocytic killing. J Exp Med 213:293-301|
|Missiakas, Dominique; Schneewind, Olaf (2016) Staphylococcus aureus vaccines: Deviating from the carol. J Exp Med 213:1645-53|
Showing the most recent 10 out of 15 publications