A novel peptide cocktail containing B and T cell epitopes confers robust protection against Staphylococcus aureus bacteremia in a murine model.

Previous Staphylococcus aureus vaccines have been unsuccessful, but it seems that including T cell immunity in the vaccine is essential for its success. This study used Metal ABC transporter substrate-binding protein (MABC), Nickel ABC transporter (NABC), and Phosphatidylinositol phosphodiesterase (PIc) B and T cell epitopes as a vaccine in a mouse bacteremia model. Mice immunized with PIc and epitope mixture groups showed robust humoral immunity and high survival rates in the bacteremia model. The highest protection level of mice was shown in the peptide mixture group, which was correlated with robust humoral response, the highest level of interferon-gamma (INF-γ) and the lowest levels of interleukin-2 (IL-2). The peptide mixture group also showed the highest count of CD8 cells. These results demonstrate that including B and T cell epitopes improved both the humoral and cellular immunity and resulted in the best outcome in the S. aureus bacteremia model. This finding has important implications for the development of future S. aureus vaccines.