IRF8 and infection: Cebpe (an important transcription factor for late neutrophil differentiation) was also downregulated in IG2 progenitors at 24 h post-PCA2 infection and in both organs after reinfection, and accompanied with the downregulation of Irf8 (an important transcription factor for monocyte differentiation), especially in MDPs and MPs, during the PCA2 infection and after the ATCC 26555 secondary infection (Figure 5D).