QS-21

Correlates of adjuvanticity: A review on adjuvants in licensed vaccines.[Pubmed:29801750]

Semin Immunol. 2018 Oct;39:14-21.

After decades of slow progress, the last years have seen a rapid acceleration of the development of adjuvanted vaccines which have lately been approved for human use. These adjuvants consist of different components, e.g. aluminium salts, emulsions such as MF59 and AS03, Toll-like receptor (TLR) agonists (CpG ormonophosphoryl lipid A (MPL) adsorbed on aluminium salts as in AS04) or combination of immunopotentiators (QS-21 and MPL in AS01). Despite their distinctive features, most of these adjuvants share some key characteristics. For example, they induce early activation (although at different levels) of innate immunity which then translates into higher antibody and cellular responses to the vaccine antigens. In addition, most of these adjuvants (e.g. MF59, AS03, AS04) clearly induce a wider breadth of adaptive responses able to confer protection against, for example, heterovariants of the influenza viruses (MF59, AS03) or against human papillomavirus strains not contained in the vaccine (AS04). Finally, the use of some of these adjuvants has contributed to significantly enhance the immune response and the efficacy and effectiveness of vaccines in the elderly who experience a waning of the immune responsiveness to infection and vaccination, as shown for MF59- or AS03-adjuvanted influenza vaccines and AS01-adjuvanted herpes zoster vaccine. These results, together with the track record of acceptable safety profiles of the adjuvanted vaccines, pave the way for the development of novel vaccines at the extremes of age and against infections with a high toll of morbidity and mortality. Here, we review the mechanisms associated with the performance of those adjuvanted vaccines in animal models and in humans through recent advances in systems vaccinology and biomarker discovery. We also provide some perspectives on remaining knowledge gaps but also on opportunities that could accelerate the development of new vaccines.

Hepatitis B surface antigen incorporated in dissolvable microneedle array patch is antigenic and thermostable.[Pubmed:28915391]

Biomaterials. 2017 Nov;145:256-265.

Alternatives to syringe-based administration are considered for vaccines. Intradermal vaccination with dissolvable microneedle arrays (MNA) appears promising in this respect, as an easy-to-use and painless method. In this work, we have developed an MNA patch (MNAP) made of hydroxyethyl starch (HES) and chondroitin sulphate (CS). In swines, hepatitis B surface antigen (HBsAg) formulated with the saponin QS-21 as adjuvant, both incorporated in HES-based MNAP, demonstrated the same level of immunogenicity as a commercially available aluminum-adjuvanted HBsAg vaccine, after two immunizations 28 days apart. MNAP application was associated with transient skin reactions (erythema, lump, scab), particularly evident when the antigen was delivered with the adjuvant. The thermostability of the adjuvanted antigen when incorporated in the HES-based matrix was also assessed by storing MNAP at 37, 45 or 50 degrees C for up to 6 months. We could demonstrate that antigenicity was retained at 37 and 45 degrees C and only a 10% loss was observed after 6 months at 50 degrees C. Our results are supportive of MNAP as an attractive alternative to classical syringe-based vaccination.

Liposomes containing monophosphoryl lipid A and QS-21 serve as an effective adjuvant for soluble circumsporozoite protein malaria vaccine FMP013.[Pubmed:28596090]

Vaccine. 2017 Jul 5;35(31):3865-3874.

Malaria caused by Plasmodium falciparum continues to threaten millions of people living in the tropical parts of the world. A vaccine that confers sterile and life-long protection remains elusive despite more than 30years of effort and resources invested in solving this problem. Antibodies to a malaria vaccine candidate circumsporozoite protein (CSP) can block invasion and can protect humans against malaria. We have manufactured the Falciparum Malaria Protein-013 (FMP013) vaccine based on the nearly full-length P. falciparum CSP 3D7 strain sequence. We report here immunogenicity and challenge data on FMP013 antigen in C57BL/6 mice formulated with two novel adjuvants of the Army Liposome Formulation (ALF) series and a commercially available adjuvant Montanide ISA 720 (Montanide) as a control. ALF is a liposomal adjuvant containing a synthetic monophosphoryl lipid A (3D-PHAD(R)). In our study, FMP013 was adjuvanted with ALF alone, ALF containing aluminum hydroxide (ALFA) or ALF containing QS-21 (ALFQ). Adjuvants ALF and ALFA induced similar antibody titers and protection against transgenic parasite challenge that were comparable to Montanide. ALFQ was superior to the other three adjuvants as it induced higher antibody titers with improved boosting after the third immunization, higher serum IgG2c titers, and enhanced protection. FMP013+ALFQ also augmented the numbers of splenic germinal center-derived activated B-cells and antibody secreting cells compared to Montanide. Further, FMP013+ALFQ induced antigen-specific IFN-gamma ELISPOT activity, CD4(+) T-cells and a TH1-biased cytokine profile. These results demonstrate that soluble CSP can induce a potent and sterile protective immune response when formulated with the QS-21 containing adjuvant ALFQ. Comparative mouse immunogenicity data presented here were used as the progression criteria for an ongoing non-human primate study and a regulatory toxicology study in preparation for a controlled human malaria infection (CHMI) trial.

Secondary metabolites from Astragalus karjaginii BORISS and the evaluation of their effects on cytokine release and hemolysis.[Pubmed:28827003]

Fitoterapia. 2017 Oct;122:26-33.

A new cycloartane sapogenol and a new cycloartane xyloside were isolated from Astragalus karjaginii BORISS along with thirteen known compounds. The structures of the new compounds were established as 3-oxo-6alpha,16beta,24(S),25-tetrahydroxycycloartane (1) and 6-O-beta-d-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane (2) by 1D- and 2D-NMR experiments as well as ESIMS and HRMS analyses. The presence of the keto function at position 3 was reported for the first time for cyclocanthogenol sapogenin of Astragalus genus. In vitro immunomodulatory effects of the new compounds (1 and 2) along with the n-BuOH and MeOH extracts of A. karjaginii at two different doses (3 and 6mug) were tested on human whole blood for in vitro cytokine release (IL-2, IL-17A and IFN-gamma) and hemolytic activities. The results confirmed that compound 2, a monodesmosidic saponin, had the strongest effect on the induction of both IL-2 (6mug, 6345.41+/-0.12pg/mL (x5), P<0.001) and a slight effect upon IL-17A (3mug, 5217.85+/-0.72pg/mL, P<0.05) cytokines compared to the other test compounds and positive controls (AST VII: Astragaloside VII; and QS-21: Quillaja saponin 21). All tested extracts and molecules also induced release of IFN-gamma remarkably ranging between 5031.95+/-0.05pg/mL, P<0.001 for MeOH extract (6mug) and 5877.08+/-0.06pg/mL, P<0.001 for compound 1 (6mug) compared to QS-21 (6mug, 5924.87+/-0.1pg/mL, P<0.001). Administration of AST VII and other test compounds did not cause any hemolytic activity, whereas QS-21 resulted a noteworthy hemolysis.