Characterization of anti-Aeromonas salmonicida antibodies from coho salmon

Coho salmon (Oncorhynchus kisutch) anti-Aeromonas salmonicida agglutinins were excluded from Sephadex G-200 and their activity was lost after partial reduction and alkylation followed by exposure to 2 M urea. Immunoelectrophoretic analysis of coho antiserum revealed anodic and cathodic populations of immunoglobulin (Ig), and the anti-A. salmonicida antibodies present 12 weeks after parenteral immunization were primarily anodic Ig. Antibodies were specifically purified by dissociation of A. salmonicida cell wall agglutinates with 15% NaCl. The purified Ig was a 17S macroglobulin, and electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that it was composed of four IgM-like subunits. The minimum coho antibody concentration required for visible agglutination of A. salmonicida cells was approximately 0.006 mug of Ig nitrogen/ml.