title: A high ratio of IC31(®) adjuvant to antigen is necessary for H4 TB vaccine immunomodulation.
abstract: 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.
authors.affiliation: a Sanofi Pasteur; Bioprocess Research and Development ; Toronto , Canada.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Aboutorabian
authors.forename: Jalil
authors.initials: J
authors.lastname: Hakimi
authors.forename: Florence
authors.initials: F
authors.lastname: Boudet
authors.forename: Sandrine
authors.initials: S
authors.lastname: Montano
authors.forename: Annie
authors.initials: A
authors.lastname: Dookie
authors.forename: Cristopher
authors.initials: C
authors.lastname: Roque
authors.forename: Salvador F
authors.initials: SF
authors.lastname: Ausar
authors.forename: Nausheen
authors.initials: N
authors.lastname: Rahman
authors.forename: Roger H
authors.initials: RH
authors.lastname: Brookes
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D002478:Cells, Cultured; D002626:Chemistry, Pharmaceutical; D004338:Drug Combinations; D006801:Humans; D056747:Immunomodulation; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D051379:Mice; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D009842:Oligopeptides / Q000494:pharmacology*; D032581:Tuberculosis Vaccines / Q000276:immunology*; D014611:Vaccination / Q000379:methods
chemical_list: D000942:Antigens, Bacterial; D004338:Drug Combinations; C544002:IC31 adjuvant; D009838:Oligodeoxyribonucleotides; D009842:Oligopeptides; D032581:Tuberculosis Vaccines; D007371:Interferon-gamma
keywords: 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; tuberculosis; vaccine