ELECTROPHORETIC PURIFICATION OF THE Vi ANTIGEN

Abstract

Several investigators have attempted to purify the Vi antigen and have described their products in terms of chemical and biological properties

Physicochemical and Biological Properties of Sonically Treated Vi Antigen

“…Naval Medical Research Institute, Bethesda, Md. 20014. were grown in a chemically defined broth medium (11) and collected by centrifugation at 35,000 X g and 4 C. The antigen was removed from the cells and purified by the method of Jarvis, Mesenko, and Kyle (9).…”

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

“…Antigenz preparations. The Vi antigen was prepared and purified as previously described (6,7) and was preserved by lyophilization of its sodium salt. The alkali-hydrolyzed form was prepared by treatment of unaltered antigen with 0.1 N NaOH at room temperature for 2 hr, precipitation with mineral acid, dialysis of the sodium salt, precipitation of the salt form with acetone, and lyophilization from aqueous solution at pH 7.0.…”

“…Jarvis et al (6) have published an electrophoretic method for purifying Vi antigen which yields a product that sediments as a single peak in the ultracentrifuge and is 15 to 40 times as active for mouse protection as the Webster or Baker preparations (9; Milner and Jarvis, Bacteriol. Proc., p. 131, 1961).…”

Isolation of Vi Antigen and a Simple Method for Its Measurement

“…Baker et al (1) obtained separation of the Vi antigen from somatic antigens in extracts of P. ballerup strain 481 and S. typhosa strain 61 by fractionation with 60% ethanol in saline at 37 C and precipitation at 0 C. However, when E. coli strain 136 and S. typhosa Ty 2 were used, separation was not complete (1). Jarvis et al (8) described a purification method using continuous-flow, paper curtain electrophoresis. The Vi antigen they obtained was found to be more immunogenic in mice than that obtained by the method of Webster et al No conclusive serological data were obtained in human volunteers for these two antigen preparations because of the limited size of the trial (11).…”

“…Webster et al (19) fractionated bacterial extracts with ethanol in the presence of sodium chloride, followed by hydrolysis with acetic acid. Baker et al (1) used ethanol-saline extraction at various temperatures, and Jarvis et al (8) employed continuous-flow, paper curtain electrophoresis. The Vi preparations yielded by these methods differ in physicochemical and immunological properties (11).…”