Design and proof of concept for targeted phage-based COVID-19 vaccination strategies with a streamlined cold-free supply chain.

Development of effective vaccines against coronavirus disease 2019 (COVID-19) is a global imperative. Rapid immunization of the entire human population against a widespread, continually evolving, and highly pathogenic virus is an unprecedented challenge, and different vaccine approaches are being pursued. Engineered filamentous bacteriophage (phage) particles have unique potential in vaccine development due to their inherent immunogenicity, genetic plasticity, stability, cost-effectiveness for large-scale production, and proven safety profile in humans. Herein we report the development and initial evaluation of two targeted phage-based vaccination approaches against SARS-CoV-2: dual ligand peptide-targeted phage and adeno-associated virus/phage (AAVP) particles. For peptide-targeted phage, we performed structure-guided antigen design to select six solvent-exposed epitopes of the SARS-CoV-2 spike (S) protein. One of these epitopes displayed on the major capsid protein pVIII of phage induced a specific and sustained humoral response when injected in mice. These phage were further engineered to simultaneously display the peptide CAKSMGDIVC on the minor capsid protein pIII to enable their transport from the lung epithelium into the systemic circulation. Aerosolization of these "dual-display" phage into the lungs of mice generated a systemic and specific antibody response. In the second approach, targeted AAVP particles were engineered to deliver the entire S protein gene under the control of a constitutive CMV promoter. This induced tissue-specific transgene expression, stimulating a systemic S protein-specific antibody response in mice. With these proof-of-concept preclinical experiments, we show that both targeted phage- and AAVP-based particles serve as robust yet versatile platforms that can promptly yield COVID-19 vaccine prototypes for translational development.
Competing Interests: Competing interest statement: D.I.S., W.A., and R.P. are listed as inventors on a patent application related to this technology (International Patent Application no. PCT/US2020/053758, entitled “Targeted Pulmonary Delivery Compositions and Methods Using Same”). Provisional patent application nos. 63/048, 279, and 63/161,136, entitled “Enhancing Immune Responses Through Targeted Antigen Expression,” have also been filed on the technology and intellectual property reported here. PhageNova Bio has licensed these intellectual properties and D.I.S., F.H.F.T., C.M., V.J.Y., T.L.S., S.K.L., W.A., and R.P. may be entitled to standard royalties. R.P., S.K.L., and W.A. are founders and equity stockholders of PhageNova Bio. S.K.L. is a board member and R.P. is chief scientific officer and a paid consultant of PhageNova Bio. V.J.Y. is currently a full-time employee of PhageNova Bio. R.P. and W.A. are founders and equity shareholders of MBrace Therapeutics; R.P. serves as the chief scientific officer and W.A. is a member of the scientific advisory board at MBrace Therapeutics. F.I.S. is currently a full-time employee of MBrace Therapeutics. These arrangements are managed in accordance with the established institutional conflict-of-interest policies of Rutgers, The State University of New Jersey.
(Copyright © 2021 the Author(s). Published by PNAS.)