Abstract
Current parenteral coronavirus disease 2019 (Covid-19) vaccines inadequately protect against infection of the upper respiratory tract. Additionally, antibodies generated by wild type (WT) spike-based vaccines poorly neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. To address the need for a second-generation vaccine, we have initiated a preclinical program to produce and evaluate a potential candidate. Our vaccine consists of recombinant Beta spike protein coadministered with synthetic CpG adjuvant. Both components are encapsulated within artificial cell membrane (ACM) polymersomes, synthetic nanovesicles efficiently internalized by antigen presenting cells, including dendritic cells, enabling targeted delivery of cargo for enhanced immune responses. ACM vaccine is immunogenic in C57BL/6 mice and Golden Syrian hamsters, evoking high serum IgG and neutralizing responses. Compared to an ACM-WT spike vaccine that generates predominantly WT-neutralizing antibodies, the ACM-Beta spike vaccine induces antibodies that neutralize WT and Beta viruses equally. Intramuscular (IM)-immunized hamsters are strongly protected from weight loss and other clinical symptoms after the Beta challenge but show delayed viral clearance in the upper airway. With intranasal (IN) immunization, however, neutralizing antibodies are generated in the upper airway concomitant with rapid and potent reduction of viral load. Moreover, antibodies are cross-neutralizing and show good activity against Omicron. Safety is evaluated in New Zealand white rabbits in a repeated dose toxicological study under Good Laboratory Practice (GLP) conditions. Three doses, IM or IN, at two-week intervals do not induce an adverse effect or systemic toxicity. Cumulatively, these results support the application for a Phase 1 clinical trial of ACM-polymersome-based Covid-19 vaccine (ClinicalTrials.gov identifier: NCT05385991 ).
Keywords: ACM; Beta spike; Covid-19; intranasal; polymersome; vaccine.
【저자키워드】 COVID-19, vaccine., intranasal, polymersome, ACM, Beta spike, 【초록키워드】 coronavirus disease, neutralizing antibody, antibodies, SARS-CoV-2, Vaccine, coronavirus, clinical trial, Safety, antibody, hamsters, Infection, Toxicity, omicron, immunization, variants, viral clearance, dendritic cells, Spike protein, airway, Viral load, mice, immune responses, Practice, Beta, hamster, upper respiratory tract, wild type, CpG, dose, antigen presenting cells, Phase 1, Support, reduction, weight loss, adverse effect, acute respiratory syndrome, clinical symptom, immunogenic, serum IgG, doses, component, cell membrane, Spike-based vaccine, Good, C57BL/6, repeated, neutralize, current, neutralizing responses, PROTECT, evaluate, virus, evaluated, generate, induce, initiated, conditions, interval, New, cross-neutralizing, delivery of cargo, 【제목키워드】 spike, Formulation, artificial, Beta, second, Generation,