FAS and animal viral hepatitis: Accumulating evidence supports the role of liver cell apoptosis in the pathogenesis of viral hepatitis.27 Although there are multiple modes of programmed cell death, pyroptosis and apoptosis cascades through the extrinsic and intrinsic pathways are the predominant forms for viral hepatitis.28 The extrinsic signaling is activated via the cell surface death receptors including TNFR1, TRAIL‐R1, and Fas.