Experimental reovirus hepatitis in newborn chicks

The avian reovirus "UM 1-203" originally isolated in the United States from chickens with tenosynovitis was pathogenic for the newborn chick infected by parenteral inoculation. It induced plurivisceral lesions, which became particularly intense in the liver. The intense local multiplication of the virus provoked a necrotizing hepatitis; viral titers were maintained around an E.I.D.50 of 10(8)/0.2 ml of organ suspension in chicks killed between the 3rd and 5th days after inoculation. As a specific cellular response to the viral multiplication, numerous polykaryocytes formed and increased in number, then regressed and disappeared from the hepatic parenchyma. By histologic and electron microscopic examination at progressive times after infection, the virus was recognizable in the polykaryocyte cytoplasm. In chicks that survived longer (killed the 5th and 6th days after inoculation), regeneration of the hepatic parenchyma occurred and seemed to develop from groups of dense hepatocytes that either lacked the virus or survived the acute phase of infection.