As the SARS-CoV-2 trimeric Spike complex is a major target of the immune system, it could be a useful ingredient for vaccine and diagnostic applications. Effective vaccines and sensitive diagnostic tools for COVID-19 are urgently needed, and systems to produce and deliver these tools in sufficient quantities are required. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the 2019 coronavirus disease (COVID-19) pandemic which presents an unprecedented challenge to societies globally. Introduction, synopsis of results and conclusions Keywords: SARS-CoV-2 trimeric Spike CHO cells manufacturability vaccines diagnostics. The process described here will enable production of sufficient high-quality trimeric Spike protein to meet the global demand for SARS-CoV-2 diagnostic tests and potentially vaccines. The diagnostic sensitivity and specificity for detection of serum SARS-CoV-2 specific IgG1 was investigated and found to exceed that of Spike fragments (S1 and RBD). Binding to susceptible cells was shown using a virus-inhibition assay. The trimeric conformation was confirmed using electron microscopy and HPLC analysis. The processes are chemically defined and based on clonal, suspension-CHO cell populations and on protein purification via a two-step, scalable down-stream process. Here, we outline scalable, GMP-compliant, chemically defined processes for production of two cell secreted, stabilized forms of the trimeric Spike protein (Wuhan and D614G variants). The poor manufacturability now threatens availability of these proteins for vaccines and diagnostic tests. Coronavirus Spikes are large, heavily glycosylated, homo-trimeric complexes, with inherent instability. In the current pandemic context, global demand for Spike proteins has rapidly increased and could exceed hundreds of grams annually. Most neutralizing antibodies against SARS-CoV-2 are directed against the Spike, making it the antigen of choice for use in vaccines and diagnostic tests. The Spike protein of SARS-CoV-2 is essential for virus entry into human cells. These levels of antibodies are enough to prevent infection in a cell culture model (Vero cells) of coronavirus infections. Recently, after the publication, we found that the produced Spike protein induces a large production of antibodies by the immune systems of rabbits and horses. The following will briefly provide key findings of the paper. The preliminary studies of these proteins leave promising results and hopes for a valuable product. In June, the production was so effective that tens of milligrams of high quality, highly purified protein could be delivered to research teams in EU and US. In May 2020, scientists at ExcellGene succeeded in making the same chinese hamster ovary cell line produce the Spike protein from the surface of SARS-CoV-2. Results showed that merely one injection of the protein trimer was enough to give sterilizing immunity in mice, thereby stopping the virus from replicating entirely. Subsequently the scientists effectively isolated and purified the protein trimers, which made them suitable for use in a vaccine. Using a cell line from Chinese Hamster Ovary (CHO) cells, the scientists were able to produce the desired proteins in the form of a trimer – a complex structure consisting of three identical protein molecules. Out of all the potential variants, one was chosen for full development. This exciting work, funded by EU Horizon 2020 and conducted in collaboration with 13 other research groups, led to the construction of tens of variants of the GP1 and GP2 proteins. A subunit vaccine contains a small part of the original virus – in this case the GP1/GP2 proteins found on the surface of the Ebola virus. Work had been carried out to produce a so-called “subunit vaccine” against Ebola virus. Scientists at ExcellGene had already faced a similar challenge in the years 2016-2019. She wanted them to use their expertise to produce a part of the virus, to serve as a vaccine or diagnostic ingredient. By late February, the health situation around the world was serious, and Maria Wurm, CEO of ExcellGene, called upon her team. In January, Chinese scientists had released a full sequence of the viral RNA. This virus was named SARS-CoV-2 and it brought a new disease upon the world: COVID-19. In the early months of 2020, it became clear that the world was facing a new threat: a contagious, potentially lethal corona virus originated in Wuhan, China.
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