A high ratio of IC31(®) adjuvant to antigen is necessary for H4 TB vaccine immunomodulation.
A tuberculosis (TB) vaccine consisting of a recombinant fusion protein (H4) and a novel TLR9 adjuvant (IC31) is in clinical development. To better understand the H4-IC31 ratio, we measured the binding capacity of IC31 for H4 protein and immunized mice with formulations that contained limiting to excess ratios of IC31 to H4. An immunomodulated H4-specific IFNγ response was only observed when IC31 was present in excess of H4. Since TLR expression is species-specific and the vaccine is intended to boost BCG-primed immunity, we questioned whether data in mice would translate to humans. To address this question, we used the fresh human Whole Blood (hWB) recovered from BCG-vaccinated subjects to screen H4-IC31 formulations. We found IC31 modulation in hWB to be quite distinct from the TLR4-Adjuvant. Unlike TLR4-Adjuvant, IC31 formulations did not induce the pro-inflammatory cytokine TNFα, but modulated a robust H4-specific IFNγ response after 12 d of culture. We then re-stimulated the fresh hWB of 5 BCG-primed subjects with formulations that had excess or limiting IC31 binding for H4 protein and again found that an immunomodulated H4-specific IFNγ response needed an excess of IC31. Finally, we monitored the zeta (ζ) potential of H4-IC31 formulations and found that the overall charge of H4-IC31 particles changes from negative to positive once IC31 is in greater than 9-fold excess. Using two diverse yet mutually supportive approaches, we confirm the need for an excess of IC31 adjuvant in H4 TB vaccine formulations and suggest surface potential may be an important factor.
['Aboutorabian|Sepideh|S|', 'Hakimi|Jalil|J|', 'Boudet|Florence|F|', 'Montano|Sandrine|S|', 'Dookie|Annie|A|', 'Roque|Cristopher|C|', 'Ausar|Salvador F|SF|', 'Rahman|Nausheen|N|', 'Brookes|Roger H|RH|']
D000818:Animals D000942:Antigens, Bacterial D002478:Cells, Cultured D002626:Chemistry, Pharmaceutical D004338:Drug Combinations D006801:Humans D056747:Immunomodulation D007371:Interferon-gamma D007963:Leukocytes, Mononuclear D051379:Mice D009838:Oligodeoxyribonucleotides D009842:Oligopeptides D032581:Tuberculosis Vaccines D014611:Vaccination
vaccine tuberculosis BCG, Bacillus Calmette-Guérin H4, TB, Antigen IC31 adjuvant modulation IC31®, Valneva Adjuvant consisting of KLK and ODN1a IFNγ, Interferon gamma KLK, Antimicrobial peptide H-KLKL5KLK-OH ODN1a, Oligodeoxynucleotide TB, Tuberculosis TLR, Toll-like Receptor TLR4, Toll-like Receptor 4 TLR4-Adjuvant, TLR4A combined with an aluminum salt adjuvant TLR4A, TLR4 Agonist TLR9, Toll-like Receptor 9 TNFα, Tumor Necrosis Factor alpha WBA functionality hWB, Human Whole Blood