Evaluation of two WHO First International Standards for Vi polysaccharide from Citrobacter freundii and Salmonella enterica subspecies enterica serovar Typhi

Publication date: Available online 27 November 2018Source: BiologicalsAuthor(s): Fang Gao, Carolyn Swann, Peter Rigsby, Sjoerd Rijpkema, Kay Lockyer, Alastair Logan, Barbara Bolgiano, Thierry Pronce, Olivier Germay, Valérian Bunel, Wim Van Molle, Lorenzo Tesolin, Derek J. Hodgson, Yves Aubin, Richard Siggers, Bin Wang, Haoyu Liang, Ming Zeng, Ani Li, Yueping LiuAbstractNumerous Vi capsular polysaccharide (Vi PS) conjugate vaccines to protect young children and infants from Typhoid are either licensed or under development. These vaccines are evaluated by laboratory methods to ensure their potency and that quality requirement are met. International Standard (IS) preparations of Vi PS are needed to calibrate and harmonise these assays. Twenty laboratories from 12 countries participated in a collaborative study to evaluate two candidate ISs: Citrobacter freundii Vi PS (NIBSC code 12/244) and Salmonella enterica serovar Typhi Vi PS (16/126). On the basis of returned results and stability profiles, these standards were established by the WHO Expert Committee on Biological Standardization in Oct 2017 as the First WHO IS for C. freundii Vi PS with a content of 1.94 ± 0.12 mg Vi PS per ampoule (expanded uncertainty with coverage factor of k = 2.11 corresponding to a 95% level of confidence) and the First WHO IS for S. Typhi Vi PS with a content of 2.03 ± 0.10 mg Vi PS per ampoule (expanded uncertainty with coverage factor of k = 2.11), as determined by quantitat...
Source: Biologicals - Category: Biology Source Type: research