Some Serological Relationships of the S, R, and G Phases ofBacillus salmonicida

Abstract

Culture phases S, R, and G of B. salmonicida have been established previously (Duff 1937). The present problem concerns the serological examination of the phases within each of a number of strains, and of the relationships existing between the phases of different strains, by means of reciprocal agglutinin absorption. Antigens were killed with 02% formaldehyde; suspensions for agglutination made in 0.05% NaCl. R antigen always showed a lower absorptive capacity than S antigen. In each of 5 B. salmonicida strains, antigenic composition appeared of the form R=S+n; in 3 other strains, S1= R1+n1. A relationship also exists between the n and n1 antigens, as shown by the common agglutinability of the correct phase of all strains by a monovalent absorbed n antiserum. A limited number of previously unexamined strains were found always to fall into one of 2 groups depending on whether the R or the S phase was agglutinated by monovalent n antiserum. No correlation exists between pathogenicity and the above serological differences. All S''s are pathogenic, no R or G is pathogenic. G phase cells appear to be composed in part of individual G antigen and in part of antigen also possessed by cells of the S and R phases.