Isolation of influenza A virus from budgerigars and its serological characterization.

A hemagglutinating agent was isolated from the respiratory organs of budgerigars suffering from diarrhea and malnutrition. This agent, possessing neuraminidase activity, was identified as influenza A virus by the double immunodiffusion test. The results of hemagglutination and neuraminidase-inhibition tests with monospecific antisera to the isolated surface antigens showed that the isolates possessed Hav4 hemagglutinin and Nav1 neuraminidase subunits both of which were closely related to the corresponding antigens of A/duck/Czech/56 (Hav4 Nav1).