@article{mbs:/content/journal/jmm/10.1099/jmm.0.047159-0, author = "Ahmadi, H. and Tabaraie, B. and Maleknia, S. and Shapouri, R. and Nejati, M. and Pour Mirza Gholi, F. and Hedayati, M. and Sadati, M. and Zahednia, S. and Sharifat Salmani, A.", title = "Immunological evaluation of Vi capsular polysaccharide of Salmonella enterica subsp. Typhi vaccine by serum bactericidal assay", journal= "Journal of Medical Microbiology", year = "2013", volume = "62", number = "2", pages = "283-286", doi = "https://doi.org/10.1099/jmm.0.047159-0", url = "https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.047159-0", publisher = "Microbiology Society", issn = "1473-5644", type = "Journal Article", abstract = " Salmonella enterica subsp. Typhi (S. Typhi) Vi antigen capsular polysaccharide (Vi-CPS) is a licensed vaccine against typhoid fever. As there is no animal model for S. Typhi fever to evaluate the protective efficacy of the Vi-CPS vaccine, a serum bactericidal assay (SBA) is the recommended ‘gold standard’ to evaluate its potency. Vi-CPS was extracted from S. Typhi Ty6S (CSBPI-B191) using a modified Gotschlich method. Purified Vi-CPS (50 µg) was injected intramuscularly into three groups of five rabbits; group 2 received an additional booster dose of 50 µg Vi-CPS on day 15 and group 3 received two additional boosters on days 15 and 30. The sera obtained from each group were tested by SBA on days 0, 15, 30 and 45. The anti-Vi-CPS titres for groups 1, 2 and 3 on days 15, 30 and 45 were 4, 16 and 16; 4, 32 and 32; and 16, 64 and 64, respectively. Thus, Vi-CPS was shown to be a potent immunogen, as even one dose could induce an efficient bactericidal effect against S. Typhi. Although Vi-CPS is a reliable vaccine, sometimes depolymerization during purification can affect its potency, which can be resolved through a potency test. As the passive haemagglutination test recommended by the World Health Organization does not indicate vaccine potency, we recommend using an SBA to evaluate the bactericidal ability of Vi-CPS.", }