Figure 3.

Figure 3.

Both RSH and SAS (p)ppGpp synthetases contribute to Staphylococcus aureus virulence in a systemic zebrafish infection model. Survival of zebrafish larvae injected with S. aureus at 30 hours postfertilization. Survival was monitored until 93 hpi when the larvae reached 5.2 days postfertilization. A, Injection of WT, (p)ppGpp⁰, and ΔrelQP (dose 3000–4000 CFU). B, Injection of WT and rel_syn (dose 1500 CFU). C, Injection of WT iTET, (p)ppGpp⁰ iTET, and (p)ppGpp⁰ iTET-rel (dose 3000–4000 CFU). D, Injection of WT iTET, (p)ppGpp⁰ iTET, and (p)ppGpp⁰ iTET-relP (dose 3000–4000 CFU). A–D, Statistical significance was determined by log-rank (Mantel-Cox) test: **P < .01, ***P < .001. A–C, Experiments were performed in triplicate, while (D) was performed in quadruplicate. Abbreviations: (p)ppGpp, guanosine tetraphosphate/guanosine pentaphosphate; (p)ppGpp⁰, (p)ppGpp null mutant; CFU, colony-forming unit; hpi, hours postinfection; RSH, RelA/SpoT homologue; SAS, small alarmone synthetase; WT, wild type.