Figure 6.

Targeting metal-binding lipoproteins confer broad protection against E. faecalis and E. faecium clinical strains. Using E. faecalis OG1RF as a reference strain, percentage of opsonic killing via antibody-mediated neutrophil opsonization using multi-antigen antisera (EfaA + AdcA + AdcAII) was compared against a list of (A) E. faecalis and (B) E. faecium clinical strains. Alum antisera is used as sera control. Each data point represents the average of 3 biological replicates of E. faecalis OG1RF tested in a single experiment. For all sera groups, experiments have been repeated at least on four non-consecutive days. Error bars represent the standard error of margin (SEM). For A–B, pooled neutrophils in each experiment were harvested from 7 to 8 de-identified human donors. Statistical analysis was performed using unpaired t-test with Welch’s correction. * P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001. For active immunization studies, total CFUs were recovered from (C) peritoneal cavity, (D) spleen, and (E) kidneys after 48 hours post-infection with clinical isolates E. faecium ERV99 and E. faecalis TX0104, respectively. Data points represent groups of 10 infected mice, using two biological replicates. After running ROUT standard 1% outlier test, statistical analysis was performed using Mann–Whitney test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.