ATF6 and infection: As shown in Figures 6B,C, the phosphorylation levels of eIF2a and ATF-6 were elevated, followed by increased expression of CHOP, pro-apoptotic protein Bax (Figure 4B), and activated caspase3/9/12 mediated by WT or ΔespF/pespF infection compared with ΔespF (p < 0.05).