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, Chunlin; Liang, Haoyu; Bachtıar, Novilia Sjafri; Yang, Jae Seung; Goel, Akshay; Venkatesan, Radhika; Pasetti, Marcela F.; Pollard, Andrew J.

doi:10.1016/j.biologicals.2018.09.001

Cited by 22 publications

(26 citation statements)

References 23 publications

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“…A good correlation between our in-house ELISA and Vacczyme ELISA was observed for anti-Vi IgG levels based on either US reference Vi IgG R1, 2011 or the Vacczyme ELISA's calibrator in this study. This result supports the outcome of the previous collaborative study [18], which showed that our in-house ELISA and the Vacczyme determined a similar anti-Vi IgG potency for the US reference. Based on the correlation, we developed a statistical model to transform data from the in-house ELISA (μg/ml) to the Vacczyme ELISA (EU/ml) in the Vi-DT phase 1 study [19].…”

Section: Discussionsupporting

confidence: 91%

“…In this study, we confirmed previous results of collaborative study that a good concordance was observed between the Vacczyme ELISA and the IVI in-house ELISA, and both assays are commutable [18]. Amongst the various ELISA formats used in this study, the IVI in-house ELISA was demonstrated as a credible non-commercial alternative for the Vacczyme ELISA.…”

Section: Discussionsupporting

confidence: 90%

“…In the latter study, the anti-Vi IgG concentrations of 6 serum samples and Vi IgG R1, 2011 were determined based on NIBSC 16/138 using in-house ELISAs and the Vacczyme ELISA. NIBSC 16/138, NIBSC 10/126, and Vi-IgG R1, 2011 were assigned values of 100 international units (IU), 54 IU, and 163 IU per ampoule, respectively [18]. However, only 3 laboratories' methods, including our in-house assay, showed overall potencies of anti-Vi IgG consistent with the Vacczyme.…”

Section: Introductionmentioning

confidence: 83%

“…Recently, the NIBSC established the first human IS, NIBSC 16/138, to determine anti-Vi IgG titers in serum [18] and it is currently available to assess anti-Vi IgG levels induced by various formulations of TCVs. Despite these efforts, a direct comparison of vaccine-induced antibody responses among TCVs is not straight forward due to the absence of head-to-head trials and the lack of a standardized assay, as observed previously [17].…”

Section: Discussionmentioning

confidence: 99%

“…However, only 3 laboratories' methods, including our in-house assay, showed overall potencies of anti-Vi IgG consistent with the Vacczyme. In particular, it was reported that our assay (designated as inhouse ELISA 1) could be a suitable non-commercial alternative to the Vacczyme because it had been established successfully in another laboratory [18].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of anti-Vi IgG responses between two clinical studies of typhoid Vi conjugate vaccines (Vi-DT vs Vi-TT)

et al. 2020

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Salmonella enterica serovar Typhi (S. Typhi) is a causative agent for typhoid fever and especially critical in developing countries. Although clinical studies for various typhoid conjugate vaccines (TCVs) have been performed, there are no comparative data on the immune responses of vaccines due to lack of harmonization of the serological assay. Recently, Typbar-TCV (Vi-TT) was prequalified by WHO and recommended for vaccination in endemic areas. Forty-eight serum samples were selected from a recent Vi-DT phase 1 study based on age cohort and anti-Vi IgG levels using an in-house ELISA. Anti-Vi IgG titers of 48 sera were also determined by Vacczyme ELISA, used in a Vi-TT phase 3 trial. A good correlation between the two assays was observed when the anti-Vi IgG titer was determined using Vacczyme ELISA based on the Vi-IgG R1,2011 , U.S. reference reagent (Pearson correlation coefficient (r) = 0.991, P < 0.001) or Vacczyme ELISA calibrator (r = 0.991, P < 0.001). Based on the correlation, multiple linear regression model was developed to convert data of 281 sera (prior to vaccination and 28 days post first-dose) in the Vi-DT phase 1 study from in-house ELISA titers to Vacczyme ELISA values and then, compared with the Vi-TT results. Similar estimates of anti-Vi IgG GMT were observed after vaccination with the Vi-DT and Vi-TT vaccines [1626 EU/ml (95% CI: 1292-2047) vs 1293 EU/ml (95% CI: 1153-1449), respectively]. The method used here can be implemented to estimate and compare anti-Vi IgG levels between different clinical studies of TCVs. This approach enables comparison of the antibody responses among TCVs under development and may help facilitate licensing of new TCVs.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of anti-Vi IgG responses between two clinical studies of typhoid Vi conjugate vaccines (Vi-DT vs Vi-TT)

et al. 2020

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Glycoconjugate vaccines against Salmonella enterica serovars and Shigella species: existing and emerging methods for their analysis

et al. 2021

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The global spread of enteric disease, the increasingly limited options for antimicrobial treatment and the need for effective eradication programs have resulted in an increased demand for glycoconjugate enteric vaccines, made with carbohydrate-based membrane components of the pathogen, and their precise characterisation. A set of physico-chemical and immunological tests are employed for complete vaccine characterisation and to ensure their consistency, potency, safety and stability, following the relevant World Health Organization and Pharmacopoeia guidelines. Variable requirements for analytical methods are linked to conjugate structure, carrier protein nature and size and O-acetyl content of polysaccharide. We investigated a key stability-indicating method which measures the percent free saccharide of Salmonella enterica subspecies enterica serovar Typhi capsular polysaccharide, by detergent precipitation, depolymerisation and HPAEC-PAD quantitation. Together with modern computational approaches, a more precise design of glycoconjugates is possible, allowing for improvements in solubility, structural conformation and stability, and immunogenicity of antigens, which may be applicable to a broad spectrum of vaccines. More validation experiments are required to establish the most effective and suitable methods for glycoconjugate analysis to bring uniformity to the existing protocols, although the need for product-specific approaches will apply, especially for the more complex vaccines. An overview of current and emerging analytical approaches for the characterisation of vaccines against Salmonella Typhi and Shigella species is described in this paper. This study should aid the development and licensing of new glycoconjugate vaccines aimed at the prevention of enteric diseases.

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Typhoid Fever Vaccines

Levine,

Neuzil,

Pollard

2023

Plotkin's Vaccines

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Establishment of the first International Standard for human anti-typhoid capsular Vi polysaccharide IgG

Cited by 22 publications

References 23 publications

Comparison of anti-Vi IgG responses between two clinical studies of typhoid Vi conjugate vaccines (Vi-DT vs Vi-TT)

Comparison of anti-Vi IgG responses between two clinical studies of typhoid Vi conjugate vaccines (Vi-DT vs Vi-TT)

Glycoconjugate vaccines against Salmonella enterica serovars and Shigella species: existing and emerging methods for their analysis

Typhoid Fever Vaccines

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