CASP4 and infection: The higher degree of single cell necrosis observed in tracheal tissue after infection with swH1N1 (Figure 5) could be linked to inflammation and apoptosis, driven by the elevated transcription of pro-inflammatory cytokines (IL1A, IL1B, IL6, IL19, IL20, and IL27), inflammatory related genes from the S100 family as well as pro-apoptotic genes and proteins (CAPN14, USP18, XAF1, Caspase-13/CASP4, ISG12, and ANXA5) in lower trachea.