Some observations on the circulation of influenzaviruses in domestic and wild birds.

Four viruses isolated from poultry in the USSR and Poland were identified as influenza A strains. One strain was closely related to fowl plague virus, the second showed an antigenic relationship to A/chicken/Scotland/59 (Hav5N1), and two others were antigenically related to A/duck/Ukraine/1/63 (Hav7Neq2) and A/duck/England/56 (Hav3Nav1). Antibodies to different strains of influenzavirus were detected in sera collected from poultry and from wild birds in the northern area of the USSR. More of the sera collected from migratory sea birds in the autumn gave HI reactions than did those collected in the spring. HI reactions were of higher titre when recent locally isolated viruses were used than with reference strains of influenzavirus. Sera collected in the autumn of 1969 from wild sea birds (mostly herring gulls, ducks, arctic loons, and long-tailed ducks) frequently showed HI activity not only with avian influenzavirus but also with A/equine/Miami/1/63 (Heq2 Neq2) and A/Hong Kong/1/68 (H3N2). The significance of these findings is discussed.