(E) Sanofi, the largest vaccine manufacturer in the world, and its partner GSK just announced the result of their vaccine that is based on an adjuvanted recombinant protein for their phase II. Results showed 95% to 100% seroconversion over 722 volunteers from age 18 to age 95. Phase III will be over 35,000 adults, and will assess the efficacy of two vaccine formulations including the D614 (Wuhan) and B.1.351 (South African) SARS-CoV-2 variants.
The technique – adjuvanted recombinant protein – has already been employed by Sanofi for its influenza vaccine.
Very simply said – the DNA sequence of the spike protein of the SARS-Cov-2 is inserted into a plasmid and then to a a virus (called baculovirus) which produces the spike protein of the manufactured vaccine. In addition, an adjuvant, that helps alert the body’s immune system to the spike’s presence, and helps stimulate it to create antibodies, is added to the vaccine.
Here is more on the design of the vaccine…
- In the lab, scientists copy the spike protein’s DNA sequence, then insert it into a circular piece of DNA called a plasmid. (This is called “recombinant DNA”, because it re-combines different segments of DNA.)
- The plasmid transports the spike DNA sequence into a specialized virus, called baculovirus, that is used to help manufacture the vaccine.
- Meanwhile, specialized cells in the lab are on standby, ready to act as miniature factories. The baculovirus enters these cells, which then churn out copies of the spike protein.
- Once the cells have generated enough spike proteins, Sanofi technicians extract them from the mixture, purify them, collect them in large batches, and formulate them before dispensing them into vials.
- This candidate vaccine is designed to be used in combination with an adjuvant: a different component of the vaccine that helps alert the body’s immune system to the spike’s presence and helps stimulate it to create antibodies.
- When the vaccine is injected into the body, the spike protein is detected by the immune system, which generates antibodies that can identify and bind to it.
- These antibodies are then available to attack the spike protein on the virus surface, if it enters the body, and help stop COVID-19 disease.
- The immune system responds to the vaccine and commits the spike protein to memory, so that when the body encounters the full SARS-CoV-2 virus it will remember to generate new antibodies to counter the virus. This type of memory typically allows for a vaccine to generate longer-lasting protection from disease.
Note: The picture above is the Spike DNA sequence transported by the plasmid into the bacolovirus – image from Sanofi.
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