Studies on the O Antigen of Salmonella Typhosa

Abstract

Summary Immunological studies have demonstrated that when a somatic antigen of the “Boivin” type is freed of protein, the resultant lipopolysaccharide exhibits no loss in antigenic activity. Indeed antigenic activity in mice, rabbits, and man is increased considerably. This product approached immunological homogeneity in the quantitative precipitin test more closely than the “Boivin” type antigen, as evidenced by an improved supernatant analysis and the formation of soluble antigen-antibody complexes in the region of far antigen excess. The essentially complete agreement of agglutinin nitrogen values with total precipitable N values for horse and rabbit antisera, together with evidence that serological specificity was entirely comparable to that of intact typhoid bacilli, all provide evidence that the immunologically active form of the somatic O antigen in S. typhosa is the lipopolysaccharide.