Antibodies in blood and secretions of chickens immunized parenterally and locally with killed Newcastle disease virus vaccine.

In mammals the antibody activity in secretions is associated with the secretory IgA. This unique immunoglobulin plays a major role in immunity against infectious diseases of the alimentary and the respiratory tracts. We found a similar system of local immunity against Newcastle disease virus (NDV) in the fowl. Airway washings and bile globulins of chickens were examined by immunodiffusion and immunoelectrophoretic methods. No antigenic differences were found between the serum IgA and the secretory IgA of airway washings and of bile. The chicken IgA differs from mammalian IgA by lacking secretory component. Antibodies in the airway washings and in tears of chickens immunized by aerosol ir i.m. NDV vaccine (attenuated or inactive) were compared to serum antibodies produced by similar methods of administration. HI antibodies in secretions reached higher levels after aerosol vaccination than after i.m. administration, whereas in serum the situation was reversed. The antibody activity in airway washings and in tears is associated with IgA, while in serum the main antibody is IgG.