MX1 and biliary atresia: Immunostaining for Mx proteins, which mediate an early innate immune response and are highly sensitive markers for type I interferon (IFN) activity, revealed that hepatocytes and intrahepatic bile ducts in biliary atresia are positive for Mx, suggesting the presence of viruses in hepatocytes and biliary epithelial cells of patients with biliary atresia [33].