1.Remdesivir is designed to obstruct the stage of replication, when the virus creates copies of itself.

  • How does replication of coronavirus take place?

  • How exactly does remdesivir target this enzyme?

  • How far has this action been established?

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What is the context about?

  • In all the debate over the efficacy of remdesivir in treating COVID-19 patients, what has been clear is the way the drug acts — or is meant to act — against the novel coronavirus SARS-CoV2.
  • Remdesivir is designed to obstruct the stage of replication, when the virus creates copies of itself, followed endlessly by the copies creating copies of themselves.
  • Research last month concluded that remdesivir indeed works this way, and a new paper last week described the exact mechanism of interaction between the virus and the drug.

How does replication of coronavirus take place?

  • Once the virus enters the human cell, it releases its genetic material, which is then copied using the body’s existing mechanism.
  • At every stage of infection, various human proteins, virus proteins, and their interactions come into play.
  • At the replication stage, the key viral protein at play is an enzyme called RdRp (an enzyme is a kind of protein that speeds up chemical reactions within a cell).
  • It is RdRp that makes the copies, by processing components of the RNA of the virus.
  • In scientific literature, such an enzyme is called a polymerase (the p is RdRp stands for polymerase) or a replicase. In any case, this is the enzyme that is targeted by remdesivir.

How exactly does remdesivir target this enzyme?

  • In order to replicate, the copy machine processes raw material from the virus RNA, broken down by another enzyme with that specific function.
  • When a patient is given remdesivir — the inhibitor — it mimics some of this material, and gets incorporated in the replication site.
  • With remdesivir replacing the material it needs, the virus fails to replicate further.
  • These coronavirus polymerases are sloppy and they get fooled, so the inhibitor gets incorporated many times and the virus can no longer replicate.

How far has this action been established?

  • Using insect cells, researchers expressed RdRp complexes of SARS-CoV (the coronavirus responsible for SARS) and SARS-CoV2 (which causes COVID-19).
  • They found that an active compound in remdesivir inhibits the copy machines of both viruses with the same potency and mechanism of action.
  • Previously, the same team had found similar results for remdesivir action against the coronavirus that causes MERS. The drug itself was designed to act against the Ebola virus, which is not a coronavirus.