On the serology and immunobiology of listeriosis. VIII. Communication: antibody against Listeria monocytogenes in sheep without and after vaccination against listeriosis as measured by means of different serological methods.

237 sheep of 4 flocks were tested in a field trial for humoral antibody against Listeria monocytogenes (L, m.) using one serum per animal. In addition, the kinetics of antibody response to vaccination against listeriosis was determined for 20 sheep, using comparatively the bacterial agglutination test, the growth test and the agglutination-immobilization test. Since low antibody were detected in a portion of animals, only, the possibly different degree of infection of animals could not be determined by the three methods employed. After primary and revaccination, a marked kinetics of antibody response resulting in titer decrease three months after vaccination could be detected by means of the agglutination-immobilization test, only, which measured antibody of the IgG class against flagellar antigens. It is discussed whether the immune response to listeriosis infection and vaccination is primarily reflected by the reaction of the macrophage-T lymphocyte system.