COVID-19 spike variants antigen Recombinant 2019-nCoV(SARS-CoV-2) Spike S-trimer protein(S1+S2 trimer,C-6His) with furin cleavage site mutation (R682G,R683S,R685S) & T4 fibritin trimerization motif

COVID-19 recombinant SARS-CoV2 (2019 nCoV coronavirus)antigen:
Recombinant 2019-nCoV(SARS-CoV-2) Spike S-trimer protein(S1+S2 trimer,C-6His)
Recombinant 2019-nCoV(SARS-CoV-2)e Spike Protein S1+S2 domain was expressed in mammanlian cell (human cells)expression system. The target gene encoding Met1-Gln1208 was expressed with 6 HIS tag at the C-terminus.S1/S2 cleavage site (furin cleavage sequence) mutation of PRRAR to PGSAS at residues 682–685(R682G,R683S,R685S) are introduced to bolish the furin cleavage site.T4 fibritin trimerization motif is added to C-terminal of the protein to improve the stability of spike trimer protein.
Suitable for variants of Spike protein & ACE2 competition binding assay for efficacy evaluation of COVID-19 vaccines and therapeutic antibodies.
Validated in functional ELISA, other immunoassays, The antigen can also be used in drug discovery including antibody screening and lead compound candidates assay.
The world is in midst of the COVID-19 pandemic caused by SARS-CoV-2 (2019nCoV) infection.The Spike protein (S-protein) of SARS-CoV-2 (2019nCoV) mediates receptor (ACE2) binding and cell entry and is the dominant target of the immune system. The highly flexible Spike protein (S-protein), with its mobile domains, transitions from closed to open conformations to expose its receptor-binding site and, subsequently, from prefusion to postfusion conformations to mediate fusion of viral and cellular membranes. SARS-CoV-2 (2019nCoV) Spike protein (S-protein) derivatives are components of vaccine candidates and diagnostic assays, as well as tools for research into the biology and immunology of SARS-CoV-2.
GeneMedi designed Spike trimer protein, which is descripted as below

The thermostable, disulfide-bonded Spike-protein trimers construct we make is:
1)S1/S2 cleavage site (furin cleavage sequence) mutant: Modification of the coding sequence of the multibasic S1/S2 cleavage site (furin cleavage sequence) PRRAR to PGSAS at residues 682–685(R682G,R683S,R685S).
2) Trimerization statues: add exogenous trimerization signal peptides:T4 fibritin trimerization motif and a polyhistidine tag at the C-terminus..
It has been demonstrated that the designed, thermostable, closed Spike trimer can be used in serological assays in COVID-19 test. This trimer protein has potential applications as a reagent for serology, virology and as an immunogen of COVID-19 related diagnostics and vaccine development.

GeneMedi also offers pre-made gene ORF mutation plasmids of Spike trimer mutation(thermostable, disulfide-bonded Spike-protein trimers).
The pre-made gene ORF vector of Spike trimer mutation is coden optimized for mamamlian and can be used for mamalian expression.
GeneMedi also provides pre-made the lentivirus, adenovirus and AAV vector for the gene ORF plasmids of 2019 nCoV (SARS2 coronavirus).

Reference:
Xiong X, Qu K, Ciazynska KA, Hosmillo M, Carter AP, Ebrahimi S, Ke Z, Scheres SHW, Bergamaschi L, Grice GL, Zhang Y; CITIID-NIHR COVID-19 BioResource Collaboration, Nathan JA, Baker S, James LC, Baxendale HE, Goodfellow I, Doffinger R, Briggs JAG. A thermostable, closed SARS-CoV-2 spike protein trimer. Nat Struct Mol Biol. 2020 Oct;27(10):934-941. doi: 10.1038/s41594-020-0478-5. Epub 2020 Jul 31. PMID: 32737467; PMCID: PMC7116388.