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The formulation of TLR ligands and other immunomodulators has a critical effect on their vaccine adjuvant activity. In this work, the synthetic TLR4 ligand GLA was formulated with three distinct vaccine delivery system platforms (aqueous suspension, liposome, or oil-in-water emulsion). The effect of the different formulations on the adaptive immune response to protein subunit vaccines was evaluated in the context of a recombinant malaria antigen, Plasmodium berghei circumsporozoite protein (PbCSP). Antibody responses in vaccinated mice were similar for the different formulations of GLA. However, cell-mediated responses differed significantly depending on the adjuvant system; in particular, the emulsion formulation of the TLR4 ligand induced significantly enhanced cellular IFN-γ and TNF-α responses compared to the other formulations. The effects of differences in adjuvant formulation composition and physical characteristics on biological activity are discussed. These results illustrate the importance of formulation of immunostimulatory adjuvants (e.g. TLR ligands) on the resulting immune responses to adjuvanted vaccines and may play a critical role for combating diseases where T cell immunity is advantageous., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Six different adjuvants, each in combination with inactivated polio vaccine (IPV) produced with attenuated Sabin strains (sIPV), were evaluated for their ability to enhance virus neutralizing antibody titres (VNTs) in the rat potency model. The increase of VNTs was on average 3-, 15-, 24-fold with adjuvants after one immunization (serotypes 1, 2, and 3, respectively). Also after a boost immunization the VNTs of adjuvanted sIPV were on average another 7-20-27 times higher than after two inoculations of sIPV without adjuvant. The results indicate that it is feasible to increase the potency of inactivated polio vaccines by using adjuvants., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Squalene-based oil-in-water emulsions have been used for years in some seasonal and pandemic influenza vaccines. However, concerns have been expressed regarding squalene source and potential biological activities. Little information is available regarding the immunomodulatory activity of squalene in comparison with other metabolizable oils in the context of oil-in-water emulsions formulated with vaccines. The present work describes the manufacture and physical characterization of emulsions composed of different classes of oils, including squalene, long chain triglycerides, a medium chain triglyceride, and a perfluorocarbon, all emulsified with egg phosphatidylcholine. Some differences were apparent among the non-squalene oils in terms of emulsion stability, including higher size polydispersity in the perfluorocarbon emulsion, more rapid visual instability at 60°C for the long-chain triglyceride and perfluorocarbon emulsions, and an increased creaming rate in the medium-chain triglyceride emulsion at 60°C as detected by laser scattering optical profiling. The biological activity of each of these emulsions was compared when formulated with either a recombinant malaria antigen or a split-virus inactivated influenza vaccine. Overall, vaccines containing the squalene emulsion elicited higher antibody titers and more abundant long-lived plasma cells than vaccines containing emulsions based on other oils. Since squalene-based emulsions show higher adjuvant potency compared to the other oils tested, non-squalene oils may be more suitable as carriers of amphiphilic or hydrophobic immunostimulatory molecules (such as TLR agonists) rather than as stand-alone adjuvants., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

GMZ2 adjuvanted by aluminum hydroxide is a candidate malaria vaccine that has successfully passed phase 1 clinical testing in adult German and Gabonese volunteers and Gabonese children under five. Here we report a preclinical study screening a series of adjuvant vehicles and Toll-like receptor (TLR) agonists in CB6F1 mice to identify an improved formulation of GMZ2 suitable for further human clinical studies. GMZ2 formulated in an oil-in-water emulsion plus the synthetic TLR4 agonist GLA elicits the highest (a) vaccine-specific IgG2a and total IgG titers, (b) parasite-specific IFA titers, (c) levels of Type 1 cytokine responses (IFN-γ), and (d) number of long-lived-plasma cells (LLPC) secreting antibodies against both the GMZ2 fusion and its two components. Thus, GLA helps to elicit a vaccine-specific Type 1 antibody profile together with high levels of LLPC, both of which are thought to be essential for the development of long-term protective immunity against clinical malaria., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Development of a protective subunit vaccine against Leishmania spp. depends on antigens and adjuvants that induce appropriate immune responses. We evaluated a second generation polyprotein antigen (Leish-110f) in different adjuvant formulations for immunogenicity and protective efficacy against Leishmania spp. challenges. Vaccine-induced protection was associated with antibody and T cell responses to Leish-110f. CD4 T cells were the source of IFN-gamma, TNF, and IL-2 double- and triple-positive populations. This study establishes the immunogenicity and protective efficacy of the improved Leish-110f subunit vaccine antigen adjuvanted with natural (MPL-SE) or synthetic (EM005) Toll-like receptor 4 agonists.

Impairments in anti-influenza T helper 1 (Th1) responses are associated with greater risk of influenza-related mortality in the elderly. Addition of adjuvants to existing influenza vaccines could improve immune responses in the elderly. In this study, the activity of three adjuvants, an oil-in-water emulsion and a synthetic lipid A adjuvant formulated with or without the emulsion, is compared. Our results show that Fluzone combined with lipid A plus an emulsion effectively leads to greater vaccine-specific IgG2a and IgG titers, enhances hemagglutination-inhibition titers and induces Type 1 cytokine responses (IFN-gamma and IL-2) to each of the Fluzone components.

We have developed the Mycobacterium tuberculosis (Mtb) fusion protein (ID83), which contains the three Mtb proteins Rv1813, Rv3620 and Rv2608. We evaluated the immunogenicity and protective efficacy of ID83 in combination with several emulsion-formulated toll-like receptor agonists. The ID83 subunit vaccines containing synthetic TLR4 or TLR9 agonists generated a T helper-1 immune response and protected mice against challenge with Mtb regardless of route. The ID83 vaccine formulated with gardiquimod (a TLR7 agonist) also resulted in a protective response when administered intradermally, whereas the same vaccine given subcutaneously failed to provide protection. This highlights the need to explore different routes of immunization based on the adjuvant formulations used.

The marine natural product manoalide (MLD), a potent inhibitor of phospholipases, completely inactivates bee venom phospholipase A2 (PLA2) by an irreversible mechanism. It has been proposed [K. B. Glaser and R. S. Jacobs, Biochem. Pharmac. 36, 2079 (1987)] that the reaction of MLD with PLA2 may involve the selective reactivity of MLD to a peptide sequence, possibly a Lys-X-X-Lys peptide. Localization of the MLD binding site on bee venom PLA2 demonstrated that upon MLD modification of bee venom PLA2 the only change in amino acid content was an apparent loss of Lys, corresponding to approximately three of the eleven Lys residues present. Selective chemical modification of Lys residues with [14C]maleic anhydride demonstrated that all eleven Lys residues on bee venom PLA2 were accessible to this reagent (11.6 mol maleyl group incorporated/mol of PLA2). Pretreatment of PLA2 with MLD (less than 0.7% residual activity) resulted in a molar ratio of 8.7, also consistent with the loss of three Lys residues upon modification by MLD. Reverse phase high performance liquid chromatography (RP-HPLC) of the cyanogen bromide (CNBr) digestion product of MLD-treated PLA2 produced three peaks (A280). The second peak showed the most intense absorbance at 434 nm. This material corresponded to residues 81-128, as determined by gas-phase microsequence analysis. Sequencing failure was observed at Lys-88 in the MLD-treated fragment. The control carboxymethylated-PLA2 fragment corresponding to residues 81-128 sequenced beyond Lys-88 without significant change in the expected yield. These data suggest that Lys-88 may correspond to one of the three MLD-modified Lys residues. The minor absorbance at 434 nm of the CNBr fragments containing residues 42-80 and 1-36 as compared to the fragment of residues 81-128 suggests that the major MLD binding fragment residues in residues 81-128.