FIGURE 2.

The enzymatic activity of NADase is required for the intracellular growth of GAS in endothelial cells. (A,C) NADase activities of different strains were determined by co-incubation with NAD⁺ and expressed as relative percentage compared to medium alone. (B,D) HMEC-1 cells were infected with strain SF370 with heterogeneous expression of nga at M.O.I. of 10 or strain SW976 (NADase G330D) at M.O.I. of 1. The intracellular viable bacteria were counted by CFU-based assay. The data represent the means ± SEM of at least three independent experiments. ns, not significant; ^∗∗∗p < 0.001 (one- or two-way ANOVA).