Use of Affimers for Targeting S. aureus Biofilms

Staphylococcus aureus is an important cause of infective endocarditis, which is an infection of the lining of the native or prosthetic heart valves. These infections can be debilitating, even life-threatening, and are often difficult to diagnose clinically. S. aureus grows on the surfaces of medical devices and natural tissues as a biofilm. Bacteria in biofilms can be difficult to eradicate as they are less susceptible to antibiotics. Thus, biofilms associated with medical devices or chronic infections often require surgical removal or debridement, respectively. Thus, it would be clinically advantageous to be able to not only detect the presence of bacteria when a patient presents with clear signs of infection, but also to determine the source by a non-invasive method. Affimers were successfully raised against S. aureus strains SH1000, USA300 and UAMS-1 biofilms using phage display. Affimers are artificial proteins that can be used for targeting. Eleven Affimers were tested for S. aureus biofilm binding, two Affimers showed significant binding to S. aureus biofilm formed by strains SH1000, USA300 and UAMS-1. Affimers were also raised against S. aureus Proteins A and Clumping factor A, Affimer against Protein A was found to bind Protein A with KD of 118 nM. Affimers against raised here have the potential to be incorporated with microbubbles to be used for imaging and detection of biofilms in Infective endocarditis.