FIG. 3.

(A) Matrix layer (ML) of animals infected with wild-type and extracellular protease mutants. Differences in the ML thickness were determined from histological images of vegetations (magnification, ×400). The lengths between the E. faecalis biomass layer and the upper edges of ML from eight random regions of vegetations from each strain were measured and reported as mean thickness (μm, mean ± standard error of the mean [SEM]). (B) Quantification of heterophil chemotaxis in the hearts of rabbits infected with E. faecalis. Differences in the numbers of heterophils that have migrated to the bacterial vegetations were determined from histological images (magnification, ×400) and were normalized to the area of ML surrounding them. Heterophils were counted using ImageJ software from four random images of vegetations from each strain and reported as the total number of heterophils trapped per 10 mm² of ML (mean ± SEM). *, significant P values of less than 0.05 relative to V583; Φ, significant P values of less than 0.05 relative to the ΔsprE mutant (VT02).