Études immunochimiques de deux polysaccharides extraits de Salmonella johannesburg 5.58 souche sauvage et de Salmonella johannesburg 5.58 convertie par le phage ϕ 1(40)

Abstract

Three antigenic determinants (40a, 40b, and 40c) have been found on the polysaccharide R − of the wild type strain of Salmonella johannesburg 5.58. The immunodominant sugars are: 2-acetamido-2-deoxy- d-galactose for 40a and 40b, and 2-acetamido-2-deoxy- d-glucose for 40c. Most of the rabbits ( 5 7 ) synthesized antibodies (IgG) only against 40a and 40b. All these determinants are found on the same molecule of polysaccharide R −. Inhibition studies with oligosacchrides isolated from the polysaccharide R − suggest that 40a is the hexasaccharide →4)-[ d-GalNAc-(1→6)]- d-GalNAc-(1→3)- d-Man-(1→4)- d-Glc-(1→4)-[ d-GalNAc-(1→6)]- d-GalNAc having (1→6)-linked 2-acetamido-2-deoxy- d-galactose residues as the immunodominant sugars for the determinant 40a. The 2-acetamido-2-deoxy-β- d-glucose residue (the immunodominant sugar of 40c) also branches from the main polysaccharide chain. 2-Acetamido-2-deoxy- d-galactose, the immunodominant sugar of determinant 40b, occurs in Man-(1→4)-Glc-(1→4)-GalNAc, which is a part of the main chain. Transformation by phage ϕ 1(40) gives polysaccharide R +, which contains α- d-glucose residues linked to C-6 of the 2-acetamido-2-deoxy- d-galactose residues of determinant 40a. The α- d-glucose residues are the immunodominant sugar of a new determinant 1 H. A second determinant appearing after transformation and specific to polysaccharide R + (1 40) has 2-acetamido-2-deoxy-β- d-glucose as the immunodominant sugar. Since no difference in the position nor in the linkage of 2-acetamido-2-deoxyα- d-glucose residues is found between R + and R −, the specificity 1 40 may result from an alteration of the conformation of antigenic determinant 40c after the addition of the α- d-glucose residues, and may be called “conformational determinant”.