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The role of Streptococcus gordonii surface proteins SspA/B and Hsa in platelet function

Lookup NU author(s): Professor Nicholas JakubovicsORCiD


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Streptococcus gordonii colonization of damaged heart surfaces in infective endocarditis is dependent upon the recognition of host receptors by specific bacterial surface proteins. However, despite several attempts to identify the mechanisms involved in this interaction, the nature of the bacterial proteins required remains poorly understood. This study provides clear evidence that several S. gordonii surface proteins participate in the interaction with platelets to support platelet adhesion and induce platelet aggregation. S. gordonii strains were found to support strong (DL1-Challis, SK12, SK184 and Blackburn) or moderate (UB1545 Deltahsa and CH1-Challis) adhesion, or failed to support platelet adhesion (M5, M99 and Channon). In addition, under flow conditions, platelets rolled and subsequently adhered to immobilized S. gordonii at low shear (50 s(-1)) in a Hsa-dependent manner but did not interact with S. gordonii DL1 at any shear rate >50 s(-1). S. gordonii strains either induced (DL1-Challis, SK12, SK184, UB1545 Deltahsa and M99) or failed to induce (M5, CH1-Challis, Channon and Blackburn) platelet aggregation. Using a proteomic approach to identify differential cell wall protein expression between aggregating (DL1) and non-aggregating (Blackburn) strains we identified Antigen I/II family proteins SspA and SspB. Over expression of SspA or SspB in the platelet non-reactive L. lactis induced GPIIb/IIIa-dependent platelet aggregation similar to that seen with S. gordonii DL1. However, they failed to support platelet adhesion. Thus, S. gordonii has distinct mechanisms for supporting platelet adhesion and inducing platelet aggregation. Differential protein expression between strains may be important in the pathogenesis of invasive diseases such as infective endocarditis.

Publication metadata

Author(s): Kerrigan SW, Jakubovics NS, Keane C, Maguire P, Wynne K, Jenkinson HF, Cox D

Publication type: Article

Publication status: Published

Journal: Infection and Immunity

Year: 2007

Volume: 75

Issue: 12

Pages: 5740-5747

ISSN (print): 0019-9567

ISSN (electronic): 1098-5522

Publisher: American Society for Microbiology


DOI: 10.1128/IAI.00909-07


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