Intranuclear inclusions in cells infected with Newcastle Disease Virus

Cells infected by Newcastle Disease Virus were observed to contain buch int racytoplasmic and intranuclear inclusion bodies. Ultrastructurally, they co nsisted of twisted strands of about 18-20 nm diameter resembling nucleocaps ids. The presence of these inclusions was detected irrespective of host cel l or pathogenicity of the virus. In immunofluorescence and immunogold label ling experiments, these structures were tagged by an anti-P protein monoclo nal antibody. In summary, we show that intracytoplasmic and intranuclear in clusion bodies, hitherto used as a taxonomic characteristic for the genus M orbillivirus of the Paramyxoviridae, also occur in a member of the genus Ru bulavirus.