New aspects in a murine model for extrahepatic biliary atresia.

The cause of extrahepatic biliary atresia (EHBA) remains unknown, and even an animal model is still lacking. Observations in a murine infectious model (newborn Balb/c mice infected with rhesus rotavirus group A [RRV]) reported extrahepatic biliary obstruction similar to findings in children who have EHBA. In the present study, this animal experiment was repeated, and the clinical and histomorphologic changes were observed over 3 weeks. Eighty-nine newborn mice were infected with RRV, and 67% showed signs of cholestasis and delayed growth. Eight of these animals recovered spontaneously whereas the others remained icteric. Fourty-six pups were prepared for microscopic examination following a 2-day interval. From the fifth day, the whole biliary tract showed edematous swelling with cellular infiltration. Ten days later, in the extrahepatic bile duct, a transformation took place in which concentric infiltration led to complete obstruction, sometimes with prestenotic dilatation. The intrahepatic changes showed reactive necrosis and proliferation of the small bile ducts. In one 19-day-old mouse, a ballooning dilatation was observed, similar to a developing choledochal cyst. Infection with RRV induces in newborn Balb/c mice a cholestatic clinical picture with different courses of the disease leading mostly to complete biliary obstruction and secondary hepatic changes similar to EHBA in children. This is the first animal model for EHBA with complete obstruction of the extrahepatic bile duct induced by infection. These findings present a new basis for further studies.