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Powell TJ, Tang J, Mitchell R, DeRome ME, Jacobs A, Palath N, Cardenas E, Yorke M, Boyd JG, Kaba SA, Nardin E. Immunogenicity, Efficacy, and Safety of a Novel Synthetic Microparticle Pre-Erythrocytic Malaria Vaccine in Multiple Host Species. Vaccines (Basel) 2023; 11:1789. [PMID: 38140193 PMCID: PMC10748200 DOI: 10.3390/vaccines11121789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/27/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023] Open
Abstract
We previously reported a protective antibody response in mice immunized with synthetic microparticle vaccines made using layer-by-layer fabrication (LbL-MP) and containing the conserved T1BT* epitopes from the P. falciparum circumsporozoite protein. To further optimize the vaccine candidate, a benchtop tangential flow filtration method (LbL-by-TFF) was developed and utilized to produce vaccine candidates that differed in the status of base layer crosslinking, inclusion of a TLR2 ligand in the antigenic peptide, and substitution of serine or alanine for an unpaired cysteine residue in the T* epitope. Studies in mice revealed consistent superiority of the Pam3Cys-modified candidates and a modest benefit of base layer crosslinking, as evidenced by higher and more persistent antibody titers (up to 18 months post-immunization), a qualitative improvement of T-cell responses toward a Th1 phenotype, and greater protection from live parasite challenges compared to the unmodified prototype candidate. Immunogenicity was also tested in a non-human primate model, the rhesus macaque. Base layer-crosslinked LbL-MP loaded with T1BT* peptide with or without covalently linked Pam3Cys elicited T1B-specific antibody responses and T1BT*-specific T-cell responses dominated by IFNγ secretion with lower levels of IL-5 secretion. The Pam3Cys-modified construct was more potent, generating antibody responses that neutralized wild-type P. falciparum in an in vitro hepatocyte invasion assay. IgG purified from individual macaques immunized with Pam3Cys.T1BT* LbL-MP protected naïve mice from challenges with transgenic P. berghei sporozoites that expressed the full-length PfCS protein, with 50-88% of passively immunized mice parasite-free for ≥15 days. Substitution of serine for an unpaired cysteine in the T* region of the T1BT* subunit did not adversely impact immune potency in the mouse while simplifying the manufacture of the antigenic peptide. In a Good Laboratory Practices compliant rabbit toxicology study, the base layer-crosslinked, Pam3Cys-modified, serine-substituted candidate was shown to be safe and immunogenic, eliciting parasite-neutralizing antibody responses and establishing the dose/route/regimen for a clinical evaluation of this novel synthetic microparticle pre-erythrocytic malaria vaccine candidate.
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Affiliation(s)
- Thomas J. Powell
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - Jie Tang
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - Robert Mitchell
- Department of Microbiology, School of Medicine, New York University, New York, NY 10010, USA; (R.M.); (E.N.)
| | - Mary E. DeRome
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
- Multiple Myeloma Research Foundation, 383 Main Avenue, 5th Floor, Norwalk, CT 06851, USA
| | - Andrea Jacobs
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - Naveen Palath
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
- Pfizer, Inc., Andover, MA 01810, USA
| | - Edwin Cardenas
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - Michelle Yorke
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - James G. Boyd
- Artificial Cell Technologies, Inc., 5 Science Park, Suite 13, New Haven, CT 06511, USA; (J.T.); (M.E.D.); (A.J.); (N.P.); (E.C.); (M.Y.); (J.G.B.)
| | - Stephen A. Kaba
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA;
- GreenLight Biosciences, Inc., Lexington, MA 02421, USA
| | - Elizabeth Nardin
- Department of Microbiology, School of Medicine, New York University, New York, NY 10010, USA; (R.M.); (E.N.)
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