Rapid Application of the Molecular Clamp Platform for SARS-CoV-2

Efforts to develop and deploy effective vaccines against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continue at pace. Here we describe rational antigen design through to manufacturability and vaccine efficacy, of a prefusion-stabilised Spike (S) protein, Sclamp. This strategy uses an orthogonal stabilisation approach compared to canonical vaccines, in combination with the licensed adjuvant MF59 (Seqirus). In mice, the Sclamp vaccine elicits high levels of neutralising antibodies, as well as broadly reactive and polyfunctional S-specific CD4+ and cytotoxic CD8+ T cells in vivo. In the Syrian hamster challenge model (n = 70), vaccination results in reduced viral load within the lung, protection from pulmonary disease, and decreased viral shedding in daily throat swabs which correlated strongly with the neutralising antibody level. The Sclamp vaccine candidate is currently completing Phase 1 clinical evaluation, in parallel with large-scale commercial manufacture for pivotal efficacy trials and potential widespread distribution. Funding: This work was funded by CEPI. Conflict of Interest: K.J.C., D.W. and P.R.Y. are inventors of the “Molecular Clamp” patent, US 2020/0040042.