An immunoprecipitin study of the incidence of influenza A antibodies in animal sera in the Ottawa area.

A survey of over 600 'normal' sera from 14 animal species by immunoprecipitin tests in cellulose acetate using viron antigens revealed a high incidence of precipitating activity against a broad range of influenza A virus strains, particularly A2hHong Kong/1/68 and /PR8. However, serum treatments trypsin-heat-periodate, NaIO4, V. cholerae receptor-destroying enzyme (RDE), or kaolin eliminated most precipitating activity, which suggests that it was due to "non-specific" inhibitors of influenze viruses. A resistant minority could not be identified as inhibitor or antibody on this basis. Precipitation of the influenza A major type-specific antigen in virus-soluble antigens by human 7S gamma globulin antibody (IgG), demonstrated to be specific for influenza virus, was established as a reference reaction to identify similar immunoprecipitin reactions occurring between virus-soluble antigens and normal or immune sera. Complement fixation tests provided supplementary evidence for the presence of influenza A antibodies in these sera. Influenza A antibodies were found in only a few sera of six animal species: cat, dog, rabbit, goat, chipmunk, and sheep. Thus the animal species examined in the Ottawa area have not revealed an unequivocal reservoir for human influenza A viruses.