Isolation of orthomyxoviruses from migrating and domestic ducks in northern Japan in 1976--1977.

Ortho- and parmyxoviruses were isolated at high frequencies from cloacal and tracheal samples of 334 domestic and 161 migrating ducks in Miyagi and Akita Prefectures, Japan, in the winter of 1976--77. Forty-four hemagglutinating agents were isolated from these ducks. The frequency of virus isolation was much higher from the cloacal samples (6.3%) than the tracheal samples (2.6%). However, no significant difference was found in the isolation ratio between the domestic (7.8%) and migrating (6.8%) ducks. Nine strains of the hemagglutinating agents were identified as influenza A viruses and confirmed to be in pure form by complement-fixation (CF) tests and from their polypeptide profiles. The antigenic characterization of the influenza A viruses revealed the presence of several subtypes; Hav5Nav-2-3, Hav6Neq2, Hav6N2, Hav7Neq2 and Hav7N2.