• Novavex, in collaboration with Takeda, recently developed a protein-based vaccine candidate (NVX-CoV2373) that were constructed from the COVID-19 full-length spike protein, transfected into Spodoptera frugiperda (SF9, fall armyworm) cell lines, and purified.
• A stable inactivated form of premature S-protein was constructed through mutagenesis by mutating the furin cleavage site as well as incorporating 2 proline substitutions that destabilize the central alpha-helix.
• Administration of NVX-CoV2373 with Matrix-M adjuvant, a synthetic biomolecule consisting of saponins conjugated to cholesterol and phospholipids, compacted into nanoparticles have shown to induce strong immune responses like Th1 B-cell and T-cell responses as well as secretion of neutralizing antibodies in serum.

• In preclinical trials, mice were administered in increasing doses of 0.01μg, 0.1μg, 1μg, and 10μg each with 5μg of the Matrix-M. Mice at all dosages exhibit high anti-spike IgG within 3-4 weeks post-initial vaccination.
• Those vaccinated at 10μg even had complete inhibition of ACE2 receptor binding to spike protein. -Even with the smallest dosage, significant amount of inflammatory cytokines like interferon (IFN-γ), tumor necrosis factor (TNF-α), and interleukins (IL-2, IL-4, & IL-5) were secreted from effector memory T-cells.
• Histopathology of lung tissues showed significant regression of lung tissue inflammation for those administered with NVX-CoV2372 compared to placebo.

Description from Lit Review Draft:

"NVX-CoV2373 is a recombinant nanoparticle vaccine composed of trimetric full-length SARS-CoV2 spike glycoproteins and Matrix M1 adjuvant. A randomized, placebo-control, phase 1-2 trial was conducted on 131 healthy adults. It has high immunogenicity and high levels of neutralizing antibodies. On September 24, 2020, phase 3 clinical trials began and immunized 10,000 people in the next 4-6 weeks. This took place at the Nucleus Network in Herston, Queensland and Melbourne, Victoria. This vaccine candidate is a recombinant nanoparticle vaccine constructed from full-length wild-type SARS-CoV-2 spike glycoprotein. It includes Matrix M1 Which is a saponin based adjuvant made by Novavax. The rSARS-CoV-2 and Matrix M1 parts were mixed just before use. This vaccine is favorable because it can be stored between 2°C and 8°C, allowing for easy preservation and, therefore, distribution (Novavax Initiates Phase 3 Efficacy Trial of COVID-19 Vaccine in the United Kingdom | Novavax Inc. - IR Site, n.d.)."