Ses proteins as possible targets for vaccine development against Staphylococcus epidermidis infections

The opportunistic pathogen Staphylococcus epidermidis is progressively involved in device-related infections. Since these infections involve biofilm formation, antibiotics are not effective. Conversely, a vaccine can be advantageous to prevent these infections. In view of vaccine development, predicted surface proteins were evaluated on their potential as a vaccine target.

Immunoglobulins directed against S. epidermidis surface proteins SesB, M, O, Q and R were used to firstly affirm their surface location. Further, inhibitory effects of these IgGs on biofilm formation were determined in vitro on polystyrene and polyurethane surfaces and in vivo using a subcutaneous catheter mouse model. We also examined the opsonophagocytotic capacity of these IgGs.

Surface localization of the five Ses proteins was demonstrated both for planktonic and sessile cells, though to a variable extent. Ses-specific IgGs added to planktonic cells had a variable inhibitory effect on cell adhesion to polystyrene, while only anti-SesO IgGs decreased cell attachment to polyurethane catheters. Although phagocytic killing was only obtained after opsonization with SesB-specific IgGs, a significant reduction of in vivo formed biofilms was observed after administration of SesB-, SesM- and SesO-specific IgGs.

Regardless of their characterization or function, S. epidermidis surface proteins can be adequate targets for vaccine development aiming the prevention of device-related infections caused by invasive S. epidermidis strains.