Optimization of Purification Method of Vi Capsular Polysaccharide Produced By Salmonella typhi and Evaluation of its Purity in Compliance With WHO Standards.

Vi capsular polysaccharide is the major component of Vi Polysaccharide typhoid vaccines. Vi polysaccharide was produced during growth of salmonella typhi organism and Vi polysaccharide was released into fermentation broth during the fermentation process. Along with Vi polysaccharide considerable amounts impurities consisting of bacterial protein, nucleic acid and lipopolysaccharide (LPS) as well as media components contaminate in the fermentation broth. The present study deals with the Vi polysaccharide purification method based on selective precipitation of cationic detergent cetrimide and ethanol to separate impurities from Vi polysaccharide solution. Initially precipitation operation temperature was optimized. Further the concentration of cetrimide, sodium acetate & alcohol concentrations were optimized based on conventional one at time method. The final yield of purified Vi polysaccharide bulk was confirmed with the specifications defined by WHO recommendations for Vi polysaccharide vaccine. [ABSTRACT FROM AUTHOR]