title: Detection of O-acetylated Vi polysaccharide of Salmonella enterica subspecies typhi by enzyme immunoassay.
abstract: Immunisation with capsular Vi polysaccharide (Vi PS) of Salmonella enterica serovar Typhi (S. typhi) protects against typhoid. This protection depends on the presence of O-acetyl groups on the Vi PS, which form an immunodominant epitope. An antiserum raised against conjugated Vi PS was used as the basis for an indirect Enzyme Immunoassay (EIA). The antiserum did not react with lipopolysaccharide of five gram negative bacteria including S. typhi. Vi PS from three different sources was tested, and all but one of 18 native Vi PS preparations had EIA values comparable to a standard Vi PS preparation. The sensitivity of the EIA for the detection of O-acetyl groups on Vi PS was compared to an NMR spectroscopy assay (Biologicals 28 (2000) 17-24). The EIA distinguished between O-acetylated and de-O-acetylated Vi PS preparations. However, significantly lower EIA reactivity was observed only for samples which had O-acetylation levels of 25% or less. This assay should facilitate batch control of Vi vaccines.
authors.affiliation: Division of Bacteriology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar EN6 3QG, UK. srijpkema@nibsc.ac.uk
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Rijpkema
authors.forename: Zarmina
authors.initials: Z
authors.lastname: Durrani
authors.forename: Xavier
authors.initials: X
authors.lastname: Lemercinier
authors.forename: Christopher
authors.initials: C
authors.lastname: Jones
mesh_terms: D000107:Acetylation; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D007124:Immunoenzyme Techniques / Q000379:methods*; D008070:Lipopolysaccharides / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012485:Salmonella typhi / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D012972:Sodium Hydroxide / Q000494:pharmacology; D014435:Typhoid Fever / Q000276:immunology*; D014436:Typhoid-Paratyphoid Vaccines
chemical_list: D000939:Epitopes; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D014436:Typhoid-Paratyphoid Vaccines; D012972:Sodium Hydroxide; D012964:Sodium