An aminohexuronic acid as the principal hydrolytic component of the Vi antigen.

The Vi antigen is a major immunogenic component of Salmonella typhosa and has been prepared from three generically different bacterial species, Escherichia coli, Paracolobactrum ballerup, and X. typhosa (2). A comparison of certain chemical and physical properties of the purified antigens was made, and the values were similar except for significant differences in viscosity. The Vi antigens were strongly acidic polymers containing nitrogen and acetyl but without appreciable quantities of uranic, sulfuric, or phosphoric acid residues. Attempts at acid hydrolysis of the antigen by various workers (3, 4) failed to result in identifiable hydrolytic products. In the present work the hydrolysis of Vi antigen has been accomplished with strong mineral acids. The hydrolytic product thus obtained has been characterized as an aminohexuronic acid by analyses and by comparison with synthetic n-glucosaminuronic acid.l