Fig 8. pyogenes sortase mutant is susceptible to phagocytosis in human blood, and grows poorly in plasma.
S. Wild type D471, original sortase mutant AR01, sortase-complemented AR01+pAR107, and passaged AR01 (day 6), were grown to OD600 0.2, diluted 1:105, and incubated in the following conditions: 1) rotated in blood, 2) stationary in blood (phagocytes sink to the bottom), 3) rotated in blood + 20 μM cytochalasin B (inhibits phagocytosis), 4) rotated in plasma, 5) rotated in TH+Y. Blood and plasma were from a healthy donor who tested negative for antibodies specific to M protein serotype 6. Following 3 h incubation at 37°C, samples were serially diluted 10-fold, and plated on TH+Y for CFU quantification; results are presented as CFUfinal/CFUstart. Experiments were repeated 3 times in duplicate, and the results from all 3 experiments are shown; error bars represent SEM. P values compared to wild type D471 were calculated using t-test; “ns” denotes no statistical significance. # symbol denotes that one or more data points in the group were below detection level.