Isolation of a new avian paramyxovirus from budgerigar (Melopsittacus undulatus)

In 1974 an epizootic occurred among budgerigar flocks in Kunitachi, Tokyo, and a causative agent which possessed haemagglutinating, neuraminidase, and haemolytic activities was isolated from the lung of a dead budgerigar. This agent was 100 to 300 nm in diamter and pleomorphic. The width of the ribonucleo-protein was estimated to be about 20 nm. These results indicated that the virus, designated Kunitachi virus, was a member of the paramyxovirus group. The virus contained in the amniotic fluid from infected embryonated hen's eggs, however, at times displayed no haemagglutinating activity with different erythrocytes and complete haemagglutination could only be detected in purified preparations. The Kunitachi viruses including three strains recently isolated from the same host were found to be serologically distinct from the known paramyxovirus strains and appeared to constitute a new subtype of avian paramyxovirus.