As observed in the case of Nrf2 at the shorter infection time, the treatment of MG-63 cells for 24 h led to a significant down-regulation of HO-1 mRNA expression levels (infected vs. uninfected) for all the strains considered (p < 0.001 for all of them), with the exception of ST239, whose values were comparable to those of control cells and significantly increased compared with all other strains (p < 0.001 vs. all) (Figure 6C). The gene discussed is HMOX1; the disease is infection.