[Immunochemical studies of O-antigen in attenuated Salmonella mutants]

An effort was made to characterise the O-antigen structure of three amino acid auxotrophic, attenuated, immunogenic smooth-shape mutants and of one wild strain of Salmonella typhimurium. Preliminary results are reported in this paper. Experiments were first undertaken with the view to determining strain-specific variation of germ yield following batch culturing as well as the movement of lipopolysaccharide levels along with the growth curve. Then culturing rules were prepared, with one and the same harvesting limit being specified (90 per cent of the strain-specific germ count) for widely comparable bacterial batches. The lipopolysaccharides obtained by phenolwater extraction from the above bacteria were characterised by gel chromatography, following their Freeman hydrolysis to degraded polysaccharide. Almost congruent polysaccharide chain peak patterns were obtained for all four strains, but despite their smooth nature all strains also contained rough polysaccharide portions without O-specific side chains. The findings so far obtained have not yet provided sufficient knowledge to discuss a possible correlation between reduced mutant virulence and qualitatively changed O-antigen structure in comparison to wild strains.