Evidence for an aminohexuronic acid as hydrolytic product of Vi antigen

Physicochemical and Biological Properties of Sonically Treated Vi Antigen

“…Webster, Clark, and Freeman, (22), Clark, McLaughlin, and Webster (3), and Heyns et al (8) have provided evidence that the Vi antigen, first reported by Felix and Pitt (5) in 1934, is a polymer of N-acetyl-D-galactosaminuronic acid. The native antigen molecule also contains 0acetyl (2, 16) and is highly polymerized (10, 24; Jarvis et al, Federation Proc.…”

Application of optical properties of the Vi capsular polysaccharide for quantitation of the Vi antigen in vaccines for typhoid fever

“…1. Repeating structure of the S. typhi and C. freundii CPS (Vi) is an al,4-linked N-acetylgalactosaminuronic acid, O-acetylated up to 90% at the C-3 position (2,6,7,34). These glycosidic bonds are all axial-axial linkages, which form an intercharge distance of -0.43 nm in similar biopolymers (la, 16).…”

“…The CPS of Salmonella typhi (Vi) is a linear homopolymer of a hexosaminuronic acid, ai1,4-N-acetylgalactosaminuronic acid, variably O-acetylated to about 90% at the C-3 position (Fig. 1) (2,6,7,(34)(35)(36). The Vi vaccine conferred protection against typhoid fever in two clinical trials (1, 12a).…”

“…Standardization of vaccines composed of Vi or of newly developed Vi-protein conjugates has been hindered for want of a method for quantifying Vi. Colorimetric methods for measuring amino sugars or uronic acids are not applicable to the measurement of Vi because the polyhexosaminuronic acid structure is resistant to acid hydrolysis and the aminouronic acid moieties do not form the chromnophore in the carbazole assay (2,3,26,34,35,37).…”

Physicochemical Properties of the Vi Antigen Before and After Mild Alkaline Hydrolysis

“…The Vi antigen, produced by some members of the Enterobacteriaceae, is a highly acidic polyelectrolyte composed largely or entirely of galactosaminuronic acid units (3,5,14) connected through a(1-4) linkages (4). No other chemical moieties are known certainly to be present except 0-and N-acetyl groups (2,15).…”