Immunochemical Studies on Salmonella

The wild strain of Salmonella cholerae suis carries the O‐antigen specificities 6 2 and 7. The phage converted strain has specificities 6 2 , (7) and 14. Four serologically active oligosaccharides can be isolated from the O‐antigenic polysaccharide of the phage converted strain of S. cholerae suis 6 2 , (7) 14; their general formula is (Man) n → Man → Glc N Ac ↑ Glc where n ↑ 0, 1, 2 or 3. Data from precipitation inhibition studies using rabbit antisera indicate that there are several fractions of antibodies (anti 6 2 , 7, 14) all directed against the same terminal (= immunodominant) sugar trait, i. e. d ‐glucose. Chemical analysis shows that there is only one terminal non‐reducing glucose residue per “repeat unit”, both in the wild and converted strains. The position of the glucose residue, however, on the oligomannose chain is different in the wild and converted strains. It is established therefore that the change in antigenic specificity (appearance of factor 14) brought about by phage conversion of S. cholerae suis is correlated with the new and definite position of d ‐glucose on the oligomannose chain.