The Possible Role of the Staphylococcus epidermidis LPxTG Surface Protein SesC in Biofilm Formation and its use as a potentional vaccine target

Staphylococcus epidermidis is the most common cause of device-associated infections among CoNS. It was shown that surface proteins have important roles for attaching and connecting the bacterial cells to the surface of medical devices. Investigation of the most effective antibody against surface proteins in the biofilm formed by S. epidermidis, led to the SesC protein as the best candidate.

The purposes of this project were to find the function of this surface protein in biofilm formation by these bacteria and also using the protein as a potential vaccine target.

To explain the role of SesC in the biofilm, first we tried to find a sesC natural mutant in S. epidermidis. Our investigation suggests that sesC is a conserved gene in this bacterial species and specifically present in S. epidermidis, not other staphylococci.

Since our efforts to knock out sesC were unsuccessful, we used an alternative strategy, which consisted in transforming another staphylococcus, S. aureus, with sesC and investigating the resulting changes in biofilm formation. We showed that a PIA-dependent strain transformed with and expressing SesC switched to a protein-dependent biofilm formation. This suggests that SesC has an important role in connecting the cells between each other or even to the surface.

Using the antibody against SesC on the biofilm of the transformant strain with sesC, in vivo results suggest that SesC can be a good candidate for vaccine development.