Experimental reovirus hepatitis in newborn chicks.

Area of Science:

• Veterinary Virology
• Pathology

Background:

• Avian reoviruses are significant pathogens in poultry.
• Tenosynovitis in chickens is often associated with reovirus infections.

Purpose of the Study:

• To investigate the pathogenicity of avian reovirus UM 1-203 in newborn chicks.
• To characterize the lesions and cellular responses induced by the virus.

Main Methods:

• Parenteral inoculation of newborn chicks with avian reovirus UM 1-203.
• Histologic and electron microscopic examination of infected tissues.
• Viral titration in organ suspensions.

Main Results:

• The virus induced plurivisceral lesions, predominantly severe necrotizing hepatitis.
• High viral titers (E.I.D.50 of 10(8)/0.2 ml) were detected in the liver.
• Formation and subsequent regression of polykaryocytes in the hepatic parenchyma were observed.
• The virus was identified within the cytoplasm of polykaryocytes.
• Hepatic regeneration occurred in surviving chicks, originating from unaffected hepatocytes.

Conclusions:

• Avian reovirus UM 1-203 is highly pathogenic for young chickens, causing significant liver damage.
• Polykaryocyte formation is a key cellular response to viral replication in the liver.
• Hepatocyte survival and regeneration contribute to recovery from infection.