Figure 4. GBS virulence relies on host heme-activated respiration metabolism.

(A) Bioluminescence of WT(NEM316) and ΔcydA(NEMJ17) transformed with plux on agar plates. Luminescence was imaged with the IVIS 200 system (acquisition time, 1 min; binning 8) (Methods). (B) Course of infection of WT and ΔcydA GBS strains in mice. BALB/c mice were infected by intravenous injection of 2.10⁷ CFU of luminescent WT(plux) and ΔcydA(plux) GBS strains. Animal luminescence was imaged as in Fig. 3A at the indicated time points by IVIS 200 (acquisition time, 10 min; binning 8). Five mice for each time are shown and are representative of 3 independent experiments. (C) Quantification of bioluminescence in live mice at 8 h and 13 h post-infection with WT and ΔcydA strains. Luminescence from live animals infected with WT(plux) and ΔcydA(plux) was determined as in (B). Box and whiskers plot of data from 3 experiments (corresponding to a total of n = 15 mice per time point). Two-tailed Mann–Whitney was used for data analyses: 8 h, P = 0.912; 13 h, P = 0.0001. ns, not significant (P > 0.05); ***P < 0.001.