Experimental infection of chickens with an australian strain of reticuloendotheliosis VIRUS. I. clinical, pathological and haematological effects

Abstract

A wide range of clinical, pathological and haematological effects were found over a 40‐week period in chickens inoculated at 1‐day‐old with a low‐passage, cell‐culture preparation of an Australian strain of reticulo‐endotheliosis virus. Feathering defects and statistically significant depression of body weights occurred in chickens up to 8 weeks of age. Other findings in birds that died or were culled during the 40‐week experimental period included mild anaemia, leucopenia, heterophilia, hypoplasia of immune system organs, inflammation in visceral and nervous system organs, and bacterial or fungal infections. These results suggested that ill‐thrift and death in some chickens infected with reticuloendotheliosis virus may be due to secondary infections with microorganisms subsequent to damage of immune system organs by that virus. Lymphoreticular‐cell tumours of the liver, kidney or spleen were found in two birds aged 22 and 24 weeks. These results establish reticuloendotheliosis virus as a possible cause of tumours in adult fowls. Horizontal transmission of virus was demonstrated but the only abnormalities detected in the in‐contact chickens were feathering defects.