SARS-CoV-2 virus recombinant spike (S) protein receptor binding domain (RBD) fusion heterodimer (B.1.351-B.1.1.7 strains)

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, is associated with a spectrum of illness from asymptomatic infection to a severe disease requiring hospitalization and supplemental oxygen and can be fatal. The SARS-CoV-2 spike (S) protein is a class I fusion glycoprotein with an RRAR furin-like cleavage site that gives rise to the S2 stalk and S1 cap; non-covalent assembly of three S1/S2 protomers gives rise to the functional S-trimer. Upon binding to its receptor, human angiotensin-converting enzyme 2 (hACE2), the S protein undergoes significant structural rearrangement to expose the hydrophobic fusion peptide that mediates membrane fusion and intracellular viral particle release. The S-hACE2 interaction, therefore, represents a critical step in SARS-CoV-2 infection.

The active ingredient in Bimervax is a recombinant SARS-CoV-2 spike protein receptor binding domain (RBD) fusion heterodimer. Its administration elicits an immune response against the RBD antigen, resulting in the formation of neutralizing antibodies that prevent the binding of SARS-CoV-2 to ACE2 and, ultimately, viral infection. It also induces an antigen-specific T-cell immune response, which may confer additional protection against COVID-19.