A survey on adjuvant practices found that poverty-related disease (PRD) vaccination development is hampered by the lack of standardisation in models and protocols for vaccine adjuvant testing. As a result, data on adjuvants are not comparable or usable in other vaccine studies. To provide a harmonised adjuvant evaluation method, members of the 'Platform for the harmonization of vaccine adjuvant testing' (PHARVAT) project selected C57 Black6 mice as the animal model for adjuvant comparisons. For standard protocol development, study parameters were set. Some of the parameters chosen were intramuscular injection, up to 50 microlitre injection volume and three immunisations on a four-weekly immunisation schedule. PHARVAT members decided to develop an adjuvant comparison kit that included reference antigens, antisera and a standardised protocol for the harmonised comparison of adjuvants. For testing in the mice model, the three reference antigens selected were apical membrane antigen 1 (AMA1), antigen 85A, and Hepatitis B surface antigen for immune response against malaria, tuberculosis and jaundice from Hepatitis B virus respectively. These antigens were chosen because adequate quantities of good manufacturing practice (GMP)-grade antigens are available for distribution. To complement the antigens, the three suitable reference adjuvants selected were Aluminium Oxy Hydroxide for baseline reference, Squalene Oil in Water and Saponin QS21 liposomal formulation. Funding from the World Health Organization (WHO) enabled immunisation experiments in vivo on C57 Black6 mice for generation of sera that could be part of the adjuvant reference kit. for each antigen, 7.5 ml (millilitre) of antiserum was sufficient for at least 20 000 tests for each of four isotopes using enzyme-linked immunosorbent assay (ELISA) plates. The Elispot assays showed that the three antigens provided comprehensive coverage of type I/II immune responses and also accounted for bias (false negative and false positive results). The findings will be published in a peer-reviewed journal. PHARVAT findings are also available on their website, providing detailed information on the harmonised adjuvant comparison method. A repository set up at WHO will provide the high-titreed reference antisera as well as the antigens. The Vaccine Formulation Laboratory at the University of Lausanne will provide the adjuvants. Together, these measures should facilitate harmonised adjuvant comparison resulting in optimised PRD vaccination development.
Platform for the Harmonization of Vaccine Adjuvant Testing
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