Recombinant SARS-CoV-2 S-trimer Protein is produced by our Mammalian expression system and the target gene encoding Cys15-Gln1208 is expressed with a 6His tag at the C-terminus. T19I, LPP24-26del, A27S, HV69-70del, G142D, V213G, G339D, R346T,S371F, S373P, S375F, T376A, D405N, R408S, K417N, N440K, L452R, S477N, T478K, E484A, F486V, Q498R, N501Y, Y505H, D614G, H655Y, N679K, P681H, N764K, D796Y, Q954H, N969K mutations were identified in the SARS-CoV-2 variant (known as BF.7 lineage) which emerged in Europe. Six proline substitutions and furin cleavage site substitutions are introduced to stabilize the trimeric prefusion state of SARS-CoV-2 S protein and abolish the furin cleavage site, respectively.