A quantitative antibody response of man to infection or vaccination with Pasteurella tularensis.

A polysaccharide antigen, prepared from a virulent strain of Past. tularensis by phenol extraction, was employed in assaying the antibody in sera from persons recovered from infection with, or vaccinated with Past. tularensis, using the serological technique of quantitative precipitation. Antibody levels in sera of individuals vaccinated with or recovered from infection with Past. tularensis were found to resemble those observed in similar studies by other investigators, such as the antibody response to pneumococcal antigen, meningococcal polysaccharide, and blood group substances. It is suggested that the value of actively or of passively acquired antibody to an individual exposed to tularemia is dependent not on the amount of antibody alone, but also on the amount of antigen with which the antibody is capable of combining.