Development of an innovative adenovirus-inspired self-assembling vaccine platform rapidly adaptable to coronaviruses and other emergent viruses

The COVID-19 pandemic clearly shows how emergent diseases can cause severe global health and economic problems. We must be prepared to react swiftly against new pathogenic agents and this requires the development of vaccines that are safe, efficient in the long-term and easily adaptable with a short revision time. To this end, the COVID-19 mRNA and adenoviral vector vaccines have been spectacular successes, permitting rapid vaccination across the world in an unprecedented manner. Here we report the design of a new adenovirus-derived vaccine technology based on non-infectious pseudo-viral nanoparticles from the serotype 3 human adenovirus. Each nanoparticle comprises sixty identical proteins that assemble to form a 30 nm diameter spherical particle. A sequence has been engineered into the surface of this protein that enables the display of a covalently-bound target antigens. To demonstrate the efficiency of this approach, we added the SARS-CoV 2 spike protein receptor binding domain (RBD), that interacts with host cell ACE2 receptors, to the surface of the nanoparticles. We first showed that the glycosylated RBD retained its ACE2-binding function when displayed on nanoparticles. We then measured the in vivo humoral response of our vaccine candidate in mice and observed a strong antibody response after the prime injection; further levels were achieved following a second booster injection. In mice preimmunized with underivatized adenoviral nanoparticles, we tested if adenovirus seroprevalence, as frequently observed in humans, was detrimental to the RBD-mediated protection provided by our vaccine candidate. Interestingly, a strong anti-coronaviral response was still observed suggesting that existing circulating anti-adenovirus antibodies are not deleterious to our vaccine platform. We then performed pseudo-CoV 2 neutralization assays and obtained higher ID50 values than observed with COVID-19 convalescent sera, thus showing the high potential efficacy of our vaccine platform. This new vaccine technology is a tool that is easily adaptable to future SARS-CoV 2 variants and, more generally, to future emergent viruses and pathogens

A three-megabase yeast artificial chromosome Contig spanning the C57BL mouse Igh locus

International audienceThe mouse Ig H chain (Igh) complex locus is composed of >100 gene segments encoding the variable, diversity, joining, and constant portions of the Ab H chain protein. To advance the characterization of this locus and to identify all the VH genes, we have isolated the entire region from C57BL/6 and C57BL/10 as a yeast artificial chromosome contig. The mouse Ighlocus extends approximately three megabases and contains at least 134 VH genes classified in 15 partially interspersed families. Two non-Igh pseudogenes (Odc-rs8 and Rpl32-rs14 ) were localized in the distal part of the locus. This physical yeast artificial chromosome map will provide important structure and guidance for the sequencing of this large, complex, and highly repetitive locus

Vector-hexamer PCR isolation of AII insert ends from a YAC contig of the mouse Igh locus

International audienceWe have developed a simple PCR strategy, termed vector–hexamer PCR, that is unique in its ability to easily recover every insert end from large insert clones in YAC and BAC vectors. We used this method to amplify andisolate all insert ends from a YAC contig covering the mouse Igh locus. Seventy-seven ends were amplified and sequenced from 36 YAC clones from four libraries in the pYAC4 vector. Unexpectedly, 40% of the insert ends of these YACs were LINE1 repeats. Nonrepetitive ends were suitable for use as probes on Southern blots of digested YACs to identify overlaps and construct a contig. The same strategy was used successfully to amplify insert ends from YACs in the pRML vector from the Whitehead Institute/MIT-820 mouse YAC library and from BACs in pBeloBAC11. The simplicity of this technique and its ability to isolate every end from large insert clones are of great utility in genomic investigation

Mechanical Control of Cell Migration by the Metastasis Suppressor Tetraspanin CD82/KAI1

International audienceThe plasma membrane is a key actor of cell migration. For instance, its tension controls persistent cell migration and cell surface caveolae integrity. Then, caveolae constituents such as caveolin-1 can initiate a mechanotransduction loop that involves actin- and focal adhesion-dependent control of the mechanosensor YAP to finely tune cell migration. Tetraspanin CD82 (also named KAI-1) is an integral membrane protein and a metastasis suppressor. Its expression is lost in many cancers including breast cancer. It is a strong inhibitor of cell migration by a little-known mechanism. We demonstrated here that CD82 controls persistent 2D migration of EGF-induced single cells, stress fibers and focal adhesion sizes and dynamics. Mechanistically, we found that CD82 regulates membrane tension, cell surface caveolae abundance and YAP nuclear translocation in a caveolin-1-dependent manner. Altogether, our data show that CD82 controls 2D cell migration using membrane-driven mechanics involving caveolin and the YAP pathway

Elicitation of potent SARS-CoV-2 neutralizing antibody responses through immunization with a versatile adenovirus-inspired multimerization platform

International audienceVirus-like particles (VLPs) are highly suited platforms for protein-based vaccines. In the present work, we adapted a previously designed non-infectious adenovirus-inspired 60-mer dodecahedric VLP (ADDomer) to display a multimeric array of large antigens through a SpyTag/SpyCatcher system. To validate the platform as a potential COVID-19 vaccine approach, we decorated the newly designed VLP with the glycosylated receptor binding domain (RBD) of SARS-CoV-2. Cryoelectron microscopy structure revealed that up to 60 copies of this antigenic domain could be bound on a single ADDomer particle, with the symmetrical arrangements of a dodecahedron. Mouse immunization with the RBD decorated VLPs already showed a significant specific humoral response following prime vaccination, greatly reinforced by a single boost. Neutralization assays with SARS-CoV-2 spike pseudo-typed virus demonstrated the elicitation of strong neutralization titers, superior to those of COVID-19 convalescent patients. Notably, the presence of pre-existing immunity against the adenoviral-derived particles did not hamper the immune response against the antigen displayed on its surface. This plug and play vaccine platform represents a promising new highly versatile tool to combat emergent pathogens

Elicitation of potent SARS-CoV-2 neutralizing antibody responses through immunization using a versatile adenovirus-inspired multimerization platform

Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has shown that vaccine preparedness is critical to anticipate a fast response to emergent pathogens with high infectivity. To rapidly reach herd immunity, an affordable, easy to store and versatile vaccine platform is thus desirable. We previously designed a non-infectious adenovirus-inspired nanoparticle (ADDomer), and in the present work, we efficiently decorated this original vaccine platform with glycosylated receptor binding domain (RBD) of SARS-CoV-2. Cryo-Electron Microscopy structure revealed that up to 60 copies of this antigenic domain were bound on a single ADDomer particle with the symmetrical arrangements of a dodecahedron. Mouse immunization with the RBD decorated particles showed as early as the first immunization a significant anti-coronavirus humoral response, which was boosted after a second immunization. Neutralization assays with spike pseudo-typed-virus demonstrated the elicitation of strong neutralization titers. Remarkably, the existence of pre-existing immunity against adenoviral-derived particles enhanced the humoral response against SARS-CoV-2. This plug and play vaccine platform revisits the way of using adenovirus to combat emergent pathogens while potentially taking advantage of the adenovirus pre-immunity