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Establishment of the first International Standard for human anti-typhoid capsular Vi polysaccharide IgG
- Rijpkema, Sjoerd, Hockley, Jason, Logan, Alastair, Rigsby, Peter, Atkinson, Eleanor, Jin, Celina, Goldblatt, David, Liang, Haoyu, Bachtiar, Novilia S., Yang, Jae Seung, Goel, Akshay, Ramasamy, Venkatesan, Pasetti, Marcela F., Pollard, Andrew J.
- Biologicals 2018 v.56 pp. 29-38
- children, coatings, enzyme-linked immunosorbent assay, humans, immunogenicity, immunoglobulin G, infants, polysaccharides, typhoid fever, vaccines, volunteers, United States
- Vi capsular polysaccharide (Vi) conjugate vaccines, which can prevent typhoid in infants and young children, are being developed. Comparative immunogenicity studies are facilitated by an International Standard (IS) for human anti-Vi IgG. 16/138, a pool of sera from volunteers which received either Vi conjugate vaccine or plain Vi vaccine, was assessed as an IS alongside U.S. reference reagent Vi-IgGR1, 2011. Samples were tested in a commercial ELISA (n = 7), a standardised ELISA based on biotinylated Vi (n = 7) and in-house ELISAs (n = 7). Valid estimates were obtained for the potency of all samples in the commercial ELISA, and the commutability of 16/138 and Vi-IgGR1, 2011 was evident for the commercial ELISA and in-house ELISAs based on a coating of Vi and protein. The WHO Expert Committee on Biological Standardization established 16/138 as the first IS for anti-Vi IgG with 100 IU per ampoule and assigned 163 IU per vial of Vi-IgGR1, 2011.