Isolation of Vi Antigen and a Simple Method for Its Measurement

Abstract

Vi antigen was purified from saline extract of Citrobacter strain 5396/38 by enzymatic digestion, concentration with ethanol, and precipitation with hexadecyltrimethylammonium bromide. The Vi antigen prepared by this method was 18 and 230 times more protective in mice than two other preparations isolated by an earlier method utilizing acid hydrolysis. A sensitive and specific method of electroimmunodiffusion was described for measurement of Vi antigen.

Degradation of the polysaccharide component of gonococcal lipopolysaccharide by gonococcal and meningococcal sonic extracts

“…Hydrolysis of Gc2 polysaccharide for hexose, heptose, hexosamine, and 2-keto-3deoxyoctonate analyses was performed under a wide range of conditions of hydrogen ion concentration, time, and temperature. The optimal conditions for hexose and heptose analysis by gas-liquid chromatography were 6 h of hydrolysis at 100'C in 1 N HC1; for hexosamine analysis, 100'C for 5 h in 3 N HCl; and for 2-keto-3-deoxyoctonate, 15 min at 100'C in 0.025 N H2SO4. Hydrolysates for hexose, heptose, and hexosamine analysis were flash evaporated in a rotary evaporator (Fisher Scientific, Rochester, N.Y.), reconstituted in distilled water, transferred quantitatively to 5-ml Reacti-vials (Pierce Chemical Corp., Rockford, Ill.), and lyophilized.…”

A gold nanoparticles based immuno-bioprobe for detection of Vi capsular polysaccharide of Salmonella enterica serovar Typhi

“…Vi capsular polysaccharide antigen from serovar Typhi Ty2 was isolated by the acetone killed extraction method as described by Wong and Feeley. 17 In brief, serovar Typhi Ty2 cells were grown in LB broth. Bacterial cells were suspended in 10 volumes (w/v) of saline, containing 0.1% sodium azide.…”

Evaluation of community-based serologic screening for identification of chronic Salmonella Typhi carriers in Vietnam

“…A relationship between the Vi antigen, a capsular polysaccharide antigen and a virulence factor of S. Typhi, the anti-Vi antibody, and S. Typhi chronic carrier status was first identified in the 1930s. 14 However, it was not until methods to make a more highly purified Vi antigen were available 15 that the anti-Vi antibody assay became more widely used to identify chronic carriers in non-endemic settings. A serologic assay using purified Vi antigen for the identification of S. Typhi carriers was developed and has been extensively used in epidemiologic investigations.…”