Role of Fibronectin-Binding Proteins A and B inIn VitroCellular Infections andIn VivoSeptic Infections by Staphylococcus aureus

Abstract

ABSTRACTFibronectin-binding protein A (FnBPA) and FnBPB are important adhesins forStaphylococcus aureusinfection. We constructedfnbAand/orfnbBmutant strains fromS. aureusSH1000, which possesses intactrsbU, and studied the role of these adhesins inin vitroandin vivoinfections. In intravenous infection, allfnbmutants caused a remarkable reduction in the colonization rate in kidneys and the mortality rate of mice.fnbBmutant caused a more severe decrease in body weight than that caused byfnbAmutant. Serum levels of interleukin-6 and nuclear factor κB (NF-κB) activation in spleen cells were remarkably reduced infnbAorfnbA fnbBmutant infections; however, there was no significant reduction infnbBmutant infections. Inin vitrocellular infection, FnBPA was shown to be indispensable for adhesion to and internalization by nonprofessional phagocytic cells upon ingestion by inflammatory macrophages and NF-κB activation. However, both FnBPs were required for efficient cellular responses. The results showed that FnBPA is more important forin vitroandin vivoinfections; however, cooperation between FnBPA and FnBPB is indispensable for the induction of severe infection resulting in septic death.