Serological specificities of polysaccharides from four Salmonellae sharing "O" factor 8.

S. virginia (8) and S. newport (6.8) induced in sera of hyper-immunized rabbits antibodies which precipitated the respective homologous and heterologous polysaccharides as well as the polysaccharides from S. blockley (6.8) and from S. emek (8.20) by homogeneous lines of, apparent, serological identity. S. blockley, sharing with S. newport the same "O" factors, induced however two antipolysaccharides of which only one was identical with that of S. virginia. Different proteinic carriers were found to be responsible for the two induced antipolysaccharides. S. emek (820) induced antipolysaccharide antibodies which displayed a reaction of partial identity with the heterologous polysaccharides, in contrast to the serological homogeneity of precipitation, shown by the S. emek polysaccharide against the heterologous sera. The existence of a more complex structure of the S. emek polysaccharide, of which a small determinant is in common with the heterologous polysaccharides and is associated with a common proteinic carrier explains these different reactions.