ABSTRACT
The first approved vaccines for human use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are nanotechnology-based. Although they are modular, rapidly produced, and can reduce disease severity, the currently available vaccines are restricted in preventing infection, stressing the global demand for novel preventive vaccine technologies. Bearing this in mind, we set out to develop a flexible nanovaccine platform for nasal administration to induce mucosal immunity, which is fundamental for optimal protection against respiratory virus infection. The next-generation multiepitope nanovaccines co-deliver immunogenic peptides, selected by an immunoinformatic workflow, along with adjuvants and regulators of the PD-L1 expression. As a case study, we focused on SARS-CoV-2 peptides as relevant antigens to validate the approach. This platform can evoke both local and systemic cellular- and humoral-specific responses against SARS-CoV-2. This led to the secretion of immunoglobulin A (IgA), capable of neutralizing SARS-CoV-2, including variants of concern, following a heterologous immunization strategy. Considering the limitations of the required cold chain distribution for current nanotechnology-based vaccines, it is shown that the lyophilized nanovaccine is stable for long-term at room temperature and retains its in vivo efficacy upon reconstitution. This makes it particularly relevant for developing countries and offers a modular system adaptable to future viral threats.
ABSTRACT
Intranasal treatment, combined with vaccination, has the potential to slow mutational evolution of viruses by reducing transmission and replication. Here, we illustrate the development of a SARS-CoV-2 receptor-binding domain (RBD) nanoCLAMP and demonstrate its potential as an intranasally administered therapeutic. A multi-epitope nanoCLAMP was made by fusing a pM affinity single-domain nanoCLAMP (P2710) to alternate epitope-binding nanoCLAMP, P2609. The resulting multimerized nanoCLAMP P2712 had sub-pM affinity for the Wuhan and South African (B.1.351) RBD (KD < 1 pM) and decreasing affinity for the Delta (B.1.617.2) and Omicron (B.1.1.529) variants (86 pM and 19.7 nM, respectively). P2712 potently inhibited the ACE2:RBD interaction, suggesting its utility as a therapeutic. With an IC50 = 0.4 ± 0.1 nM obtained from neutralization experiments using pseudoviral particles, nanoCLAMP P2712 protected K18-hACE2 mice from SARS-CoV-2 infection, reduced viral loads in the lungs and brains, and reduced associated upregulation of inflammatory cytokines and chemokines. Together, our findings warrant further investigation into the development of nanoCLAMPs as effective intranasally delivered COVID-19 therapeutics.
ABSTRACT
BACKGROUND: There is an urgent need of a new generation of vaccine that are able to enhance protection against SARS-CoV-2 and related variants of concern (VOC) and emerging coronaviruses. METHODS: We identified conserved T- and B-cell epitopes from Spike (S) and Nucleocapsid (N) highly homologous to 38 sarbecoviruses, including SARS-CoV-2 VOCs, to design a protein subunit vaccine targeting antigens to Dendritic Cells (DC) via CD40 surface receptor (CD40.CoV2). FINDINGS: CD40.CoV2 immunization elicited high levels of cross-neutralizing antibodies against SARS-CoV-2, VOCs, and SARS-CoV-1 in K18-hACE2 transgenic mice, associated with viral control and survival after SARS-CoV-2 challenge. A direct comparison of CD40.CoV2 with the mRNA BNT162b2 vaccine showed that the two vaccines were equally immunogenic in mice. We demonstrated the potency of CD40.CoV2 to recall in vitro human multi-epitope, functional, and cytotoxic SARS-CoV-2 S- and N-specific T-cell responses that are unaffected by VOC mutations and cross-reactive with SARS-CoV-1 and, to a lesser extent, MERS epitopes. INTERPRETATION: We report the immunogenicity and antiviral efficacy of the CD40.CoV2 vaccine in a preclinical model providing a framework for a pan-sarbecovirus vaccine. FUNDINGS: This work was supported by INSERM and the Investissements d'Avenir program, Vaccine Research Institute (VRI), managed by the ANR and the CARE project funded from the Innovative Medicines Initiative 2 Joint Undertaking (JU).
