Immunodiffusion Studies with Pasteurella Tularensis Antigen-Rabbit Antibody Systems

Abstract

Sonic-vibrated antigens prepared from five strains of Pasteurella tularensis were not significantly different from the standpoint of antigenic makeup when studied by immunodiffusion techniques. Each contained at least six antigenic components, all of which were common to all strains. P. tularensis polysaccharide exhibited four components, all of which were present in all of the sonic-vibrated antigens. Serum samples from rabbits inoculated intravenously with formalin-killed suspensions of the five strains of P. tularensis showed either two or three precipitin lines 1 week after injection. After reinoculation at 7 and 11 weeks, the number of lines increased to two, three or four and three, four or five, respectively. There was no correlation between the number of precipitin lines and the strain used for immunization. There also was no correlation between the number of lines and either bacterial agglutination or polysaccharide hemagglutination titer at any specific time after immunization, although the over-all pattern of the response was similar as measured by the three tests. Polysaccharide hemagglutination titer and the number of precipitin lines were affected to a greater degree by the booster inoculations than was bacterial agglutination titer. Serum samples from different rabbits inoculated with the same strain exhibited decidedly different precipitin line patterns in immunodiffusion tests. There was no correlation between precipitin line pattern and the strain used for immunization. Problems of interpretation associated with immunodiffusion studies of complex antigen-antibody systems are presented and discussed.