TIMP1 and infection: Based on our results, which suggested a role of phagocytosis and revealed substantial tissue damage following infection, we focused on two types of virulence factors: (i) the enterococcal polysaccharide antigen (encoded by the epa locus), a rhamnopolysaccharide that has previously been shown to play a role in resistance to neutrophil uptake in vitro (34), and (ii) two major exoproteases playing a role in virulence, a gelatinase (GelE) and a serine protease (SprE) that are regulated by the Fsr quorum-sensing system (7, 31, 35).