title: A novel lipid nanoparticle adjuvant significantly enhances B cell and T cell responses to sub-unit vaccine antigens.
abstract: Sub-unit vaccines are primarily designed to include antigens required to elicit protective immune responses and to be safer than whole-inactivated or live-attenuated vaccines. But their purity and inability to self-adjuvant often result in weaker immunogenicity. Emerging evidence suggests that bio-engineered nanoparticles can be used as immunomodulatory adjuvants. Therefore, in this study we explored the potential of novel Merck-proprietary lipid nanoparticle (LNP) formulations to enhance immune responses to sub-unit viral antigens. Immunization of BALB/c and C57BL/6 mice revealed that LNPs alone or in combination with a synthetic TLR9 agonist, immune-modulatory oligonucleotides, IMO-2125 (IMO), significantly enhanced immune responses to hepatitis B virus surface antigen (HBsAg) and ovalbumin (OVA). LNPs enhanced total B-cell responses to both antigens tested, to levels comparable to known vaccine adjuvants including aluminum based adjuvant, IMO alone and a TLR4 agonist, 3-O-deactytaled monophosphoryl lipid A (MPL). Investigation of the quality of B-cell responses demonstrated that the combination of LNP with IMO agonist elicited a stronger Th1-type response (based on the IgG2a:IgG1 ratio) than levels achieved with IMO alone. Furthermore, the LNP adjuvant significantly enhanced antigen specific cell-mediated immune responses. In ELISPOT assays, depletion of specific subsets of T cells revealed that the LNPs elicited potent antigen-specific CD4(+) and CD8(+)T cell responses. Intracellular FACS analyses revealed that LNP and LNP+IMO formulated antigens led to higher frequency of antigen-specific IFNγ(+)TNFα(+)IL-2(+), multi-functional CD8(+)T cell responses, than unadjuvanted vaccine or vaccine with IMO only. Overall, our results demonstrate that lipid nanoparticles can serve as future sub-unit vaccine adjuvants to boost both B-cell and T-cell responses in vivo, and that addition of IMO can be used to manipulate the quality of immune responses.
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Gokul
authors.initials: G
authors.lastname: Swaminathan
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Thoryk
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Kara S
authors.initials: KS
authors.lastname: Cox
authors.affiliation: Medical Affairs, Merck Global Human Health, Merck & Co. Inc., Merck Sharp & Dohme Corp., North Wales, PA, United States.
authors.forename: Steven
authors.initials: S
authors.lastname: Meschino
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Sheri A
authors.initials: SA
authors.lastname: Dubey
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Kalpit A
authors.initials: KA
authors.lastname: Vora
authors.affiliation: Pharmaceutical Sciences, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Celano
authors.affiliation: Pharmaceutical Sciences, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Marian
authors.initials: M
authors.lastname: Gindy
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States.
authors.forename: Danilo R
authors.initials: DR
authors.lastname: Casimiro
authors.affiliation: Infectious Diseases and Vaccine Research, Merck Research Laboratories, Merck & Co. Inc., Merck Sharp & Dohme Corp., West Point, PA, United States. Electronic address: andrew_bett@merck.com.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bett
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D008081:Liposomes / Q000008:administration & dosage*; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D053758:Nanoparticles / Q000008:administration & dosage*; D010047:Ovalbumin / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D016896:Treatment Outcome; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D006514:Hepatitis B Surface Antigens; D008081:Liposomes; D022223:Vaccines, Subunit; D010047:Ovalbumin
keywords: Adjuvant; CD8 T cell response; Lipid nanoparticle; Subunit vaccine; TLR9 agonist