A novel bivalent fusion vaccine induces broad immunoprotection against Staphylococcus aureus infection in different murine models.

With more and more drug-resistant Staphylococcus aureus strains emerging in hospitals, there is an urgent need to develop an effective vaccine to combat S. aureus infection. In this study, we constructed a novel bivalent fusion vaccine, SpA-DKKAA-FnBPA37-507 (SF), based on the D domain of staphylococcal protein A (SpA) and the A domain of fibronectin-binding protein A (FnBPA). Immunisation with SF induced a more ideal protective effect compared with the single components alone in a sepsis model. It also showed broad immunoprotection against seven FnBPA isotypes. Vaccination with SF induced strong antibodies responses and Th1/Th17 polarized cellular responses. Further we demonstrated the protective effect of antibodies by the opsonophagocytic assay (OPA) and passive immunisation. Moreover, vaccination with SF showed protective efficacy in a murine pneumonia model and skin abscess model. These results suggest that SF can be regarded as a promising vaccine candidate for the prevention of S. aureus infections.