SARS-CoV-2 Spike Glycoprotein mRNA, South Africa Variant, HexaPro Stabilized Trimer

This modified mRNA encodes the full-length SARS-CoV-2 spike glycoprotein, stabilized by several mutations: the polybasic S1/S2 cleavage site RRAR is mutated to GSAS (residues 682 to 685); and 6 additional proline substitutions: K986P, V987P, F817P, A892P, A899P and A942P, producing a more stable HexaPro variant. In addition, T4 foldon trimerization domain is added to the C-terminus. The resulting trimeric S glycoprotein will be in an antigenically optimal pre-fusion conformation. The South Africa variant has these mutations: has K417N, E484K and N501Y.

• 5' Cap: Capped with ARCA (Anti Reverse Cap Analog, m7(3'-O-methyl)-G(5')ppp(5')G, Cap 0) or CleanCap AG (m7G(5')ppp(5')(2'OMeA)pG, Cap 1)
• 5’-UTR: derived from human alpha-globin RNA with an optimized Kozak sequence
• Codon Optimization: Human
• Mutations: K417N, E484K and N501Y; Furin site RRAR mutated to GSAS; HexaPro mutations (K986P, V987P, F817P, A892P, A899P and A942P) to ensure the S glycoprotein remains in an antigenically optimal pre-fusion conformation
• Nucleotide Modifications: mRNA modified with both Pseudo-UTP and 5mCTP
• 3’-UTR: comprises two sequence elements derived from the amino-terminal enhancer of split (AES) mRNA and the mitochondrial encoded 12S ribosomal RNA to confer RNA stability and high total protein expression.
• PolyA: 180 nt