SARS-CoV-2 wild-type full-length trimeric peak recombinant antigen. It is a full-length protein, which is active in its native trimeric form, which is stabilized in LMNG detergent.
SARS-CoV-2 has undergone a variety of mutations in the RBD domain of the spike protein that has led to the development of numerous variants in recent months. Some of the mutations occur in more than one variant and are of great value as they alter the structure of the protein, improving immune system evasion and increasing transmissibility. BioServUK offers a range of antigens including the latest Indian delta variant (B.1.617.2), the UK variant (B.1.1.7), the South African variant (B.1.351), and the Brazilian variant ( P.1).
Recombinant spike protein of SARS-CoV-2 and related viruses have proven difficult to produce in good yields in mammalian cells. Given the wide variety of potential COVID-19 diagnostic tools and therapeutic candidates that require purified peak protein and their importance to ongoing SARS-CoV-2 research, we have explored new approaches to peak production and purification.
Three transient gene expression methods based on PEI-mediated transfection of CHO or HEK293 cells in suspension culture in chemically defined media were compared for rapid production of full-length SARS-CoV-2 spike ectodomain. A high cell density protocol using DXB11 derived CHOBRI / 55E1 cells provided substantially better yields than the other methods.
Different forms of the peak ectodomain were expressed, including the wild-type SARS-CoV-2 sequence and a mutated form (to favor the expression of the full-length peak ectodomain stabilized in the pre-fusion conformation), with and without fusion to putative trimerization domains. An efficient two-step affinity purification method was also developed.
Ultimately, we have been able to produce highly homogeneous full-length peak preparations, both monomeric and trimeric, with yields of 100-150 mg / L in the harvested medium. The speed and productivity of this method support the further development of CHO-based approaches for the manufacture of recombinant peak proteins.