Adjuvant System 04 (AS04) combines the TLR4 agonist MPL (3-O-desacyl-4′-monophosphoryl lipid A) and aluminum salt. It is a new generation TLR-based adjuvant licensed for use in human vaccines. One of these vaccines, the human papillomavirus (HPV) vaccine Cervarix, is used in this study to elucidate the mechanism of action of AS04 in human cells and in mice. The adjuvant activity of AS04 was found to be strictly dependent on AS04 and the HPV Ags being injected at the same i.m. site within 24 h of each other. During this period, AS04 transiently induced local NF-κB activity and cytokine production. This led to an increased number of activated Ag-loaded dendritic cells and monocytes in the lymph node draining the injection site, which further increased the activation of Ag-specific T cells. AS04 was also found to directly stimulate those APCs in vitro but not directly stimulate CD4+ T or B lymphocytes. These AS04-induced innate responses were primarily due to MPL. Aluminum salt appeared not to synergize with or inhibit MPL, but rather it prolonged the cytokine responses to MPL at the injection site. Altogether these results support a model in which the addition of MPL to aluminum salt enhances the vaccine response by rapidly triggering a local cytokine response leading to an optimal activation of APCs. The transient and confined nature of these responses provides further supporting evidence for the favorable safety profile of AS04 adjuvanted vaccines.

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E S B I O S C I E N C E . D O N O T D I S T R I B U T E .direct ELISA appears to be an excellent surrogate for neutralizing activity and can be used to evaluate antibody response induced by L1 virus-like particle-based cervical cancer vaccines, regardless of time elapsed after vaccination (up to 6.4 years) and the age of the vaccine recipient.

Ideal methods to monitor HPV neutralizing antibodies induced by vaccination have not been established yet. Here, we evaluated systemic and cervical antibody levels induced by HPV16/18 AS04-adjuvanted vaccine (GlaxoSmithKline Biologicals) using a secreted alkaline phosphatase neutralization assay (SEAP) and ELISA. Serum and cervical secretions from 50 vaccinated women were used to assess 1) overall assay reproducibility, 2) inter-assay and inter-specimen correlation; 3) correlations between month 1 and month 12 titers. Strong correlations between SEAP-NA and ELISA were observed (serum anti-HPV16/18, ρ=0.91/0.85; cervix anti-HPV16/18, ρ=0.84/0.89). Systemic and cervical antibody measures also correlated well (ρ range: 0.64 -0.75); except at mid-cycle (ρ range: 0.28 -0.65). Correlations between antibody levels at one and twelve months following the start of vaccination were poor (ρ range: 0.16 -0.38). In conclusion, HPV16/18 VLP-based ELISA is a reliable and valid method to monitor anti-HPV16/18 neutralizing potential for the first year following vaccination; however, additional studies will be Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Conflict of Interest: Troy J. Kemp, no conflict; Alfonso García-Piñeres, no conflict; Roni T. Falk, no conflict; Sylviane Poncelet is employed by GSK Biologicals, the manufacturer of the vaccine used in this trial; Francis Dessy is employed by GSK Biologicals, the manufacturer of the vaccine used in this trial; Sandra L. Giannini is employed by GSK Biologicals, the manufacturer of the vaccine used in this trial; Ana Cecilia Rodriguez, no conflict; Carolina Porras, no conflict; Rolando Herrero, no conflict; Allan Hildesheim, no conflict; Ligia A. Pinto, no conflict. Merocel is a trademark of Medtronic Ophthalmics, a division of Medtronic Xomed, Inc., Jacksonville, FL, and Hemastix is a trademark of Bayer Corporation, Elkhart, IN. NIH Public Access Author ManuscriptVaccine. Author manuscript; available in PMC 2014 August 13.

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