Atypical disease produced in chickens by Newcastle disease virus isolated from exotic birds.

Chickens were infected with a Newcastle disease virus (NDV) recovered from exotic birds with severe clinical disease and with lesions characteristic of viscerotropic velogenic Newcastle disease (VVND). The infection in chickens was inconsistently lethal, some infected chickens were not clinically affected, and gastrointestinal involvement was only marginally evident. Pathogenicity of the virus for chickens was not detectably altered by laboratory passage in chickens or by limit dilution passage in chicken embryos. The results suggest that the difference between velogenic NDV pathotypes may not always be distinct and that clinical manifestations of VVND in chickens may not always be predictable based on signs and lesions observed in exotic birds.