Serological Relationships of S, R. and G Phases (Duff 1939) 



Following his work on the formation of S, R and G colonies of 

 B. salmonicida. Duff (1939) studied the serological relationships of 

 these phases. 



The technique followed with all sera was that of absorption with 

 a low multiple of the minimal absorbing dose, follovred by titration of 

 the absorbed serum. Minimal absorbing doses for S and G cultures were 

 always between 1:10 and 1:5, whereas the value for R cultures was neTer 

 less than 1:2. Absorptions were carried out for 4 hours at 37° C. 

 followed by ice-box storage overnight. 



Considering first the R and S interconnections, five strains 

 (GL6, CLII, SP5, ER2) were found to possess the same antigenic 

 relationship betvreen R and S phase cultures. In these strains the R 

 cells of any given strain possessed an antigen or antigens not present 

 in the S cells of the same strain. The antigenic situation may be 

 represented in symbols as R = S + n. For convenience B. salmonicida 

 strains so constituted were termed Group I strains. This relationship 

 was not found to hold for certain other strains. Three strains (CL3, 

 CL4, SP9) (Group II) displayed a different antigenic picture, in which 

 the S ceils possessed an antigen or antigens not present in the 

 corresponding R cells, or, S-j_ = R-, + n.^. 



Typing Additional Strains (Duff 1939) 



It proved impracticable to extend full reciprocal analysis to 

 further individual strains of B. salmonicida . At the same time it was 

 of definite interest to know whether other strains would all fall into 

 one or other of the serological groups (in respect to the R and S 

 relations). Therefore a tentative method for testing new strains was 

 devised by Duff (1939). It will be seen that absorption, using homologous 

 S cells, of an antiserum m.ade against the R cells of any one strain from 

 Group I yields \ih.at may be termed a "monovalent n" antiserum. A serum of 

 this ty~pe was prepared by absorbing an antiserum made against the R cells 

 of strain CL6 (Group I) with S phase of the same strain. The absorption 

 was carried out twice (table 7). 



Table 8 records the agglutinability of all strains under the 

 influence of CL6 monovalent n antisenim. The results do not necessarily 

 prove the complete identity of the 01,6 n antigen of the remaining Grotip I 

 strains or vd.th the n^ antigen of the three Group II strains. Tliey do 

 demonstrate however, that this antigen is common to R cells of all Group I 

 strains and to S cells of all Group II strains. 



In addition eleven other strains were tested in the same manner 

 with similar- results. Nine fell into Group I and two into Group 11. 



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