Investigation of cross-opsonic effect leads to the discovery of PPIase-domain containing protein vaccine candidate to prevent infections by Gram-positive ESKAPE pathogens.

Enterococcus faecium and Staphylococcus aureus are the Gram-positive pathogens of the ESKAPE group, known to represent a great threat to human health due to their high virulence and multiple resistances to antibiotics. Combined, enterococci and S. aureus account for 26% of healthcare-associated infections and are the most common organisms responsible for blood stream infections. We previously showed that the peptidyl-prolyl cis/trans isomerase (PPIase) PpiC of E. faecium elicits the production of specific, opsonic, and protective antibodies that are effective against several strains of E. faecium and E. faecalis. Due to the ubiquitous characteristics of PPIases and their essential function within Gram-positive cells, we hypothesized a potential cross-reactive effect of anti-PpiC antibodies.