The S protein was chosen as the vaccine antigen but its frequent mutations weaken the antibodies induced by the vaccination. At the University of California, scientists are proposing another antigen that is much less prone to change.
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The S protein coronavirus is a privileged target of immunity because it is responsible for an essential stage of the viral cycle, entry into the host cell. It is also a protein located on the surface of the coronavirus, it is easy to access for antibody. But’emergence of each variant reminds us, the S protein is particularly changeable. The effectiveness of vaccines suffers.
Scientists at the University of California are interested in a antigen more conserved, i.e. less subject to mutations, the polymerase viral. They showed that the cytotoxic T lymphocytes, experts in cell destruction, are able to recognize and destroy cells expressing a fragment of the viral polymerase.
Replicating the coronavirus genome
In the virus cycle, entry into the host cell is an essential step, the replication equipment genetic is just as much. In coronaviruses, whose genome is made up ofRNA, it is the viral polymerase which takes care of it. This enzyme is also called RNA-dependent RNA polymerase, since it synthesizes a strand of RNA from a template, also made of RNA.
Since it does not mutate much, the viral polymerase could be an interesting candidate in a vaccine to induce a immune response durable that does not deteriorate over time. She is similar to that of others coronavirus, potentially conferring protection against several different strains.
Viral polymerase as a vaccine antigen?
Scientists at the University of California have shown that cytotoxic T lymphocytes are able to recognize cells in culture that have epitopes, in a way fragments, of the viral polymerase. After recognizing the cells, the T lymphocytes also destroyed them.
With these elements, scientists at the University of California propose a strategy to strengthen the effectiveness of anti-Covid-19 vaccines, by adding the viral polymerase in the already existing formulas. Further studies are needed to prove the feasibility and effectiveness of this approach.
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