CAA’s Articulate – How coronavirus tricks immune system with camouflage



Context:

  • Like an intruder deactivating an alarm before entering a building without bells going off, the coronavirus SARS-CoV-2 has been found to have the same advantage entering cells.




Tricking the immune system

  • The virus produces an enzyme called nsp16, which it then uses to modify its messenger RNA cap.
    • In lay terms, messenger RNA can be described as a deliverer of genetic code to worksites that produce proteins.
  • A camouflage: Because of the modifications, which fool the cell, the resulting viral messenger RNA is now considered as part of the cell’s own code and not foreign.

Significance for vaccine making:

  • Deciphering the 3D structure of nsp16, paves the way for rational design of antiviral drugs for Covid-19 and other emerging coronavirus infections.
  • The new small molecules in the drugs would inhibit nsp16 from making the modifications. The immune system would then recognise the virus as foreign, and target it.


About Ribonucleic acid (RNA)

  • In all living cells, the process of translating genetic information from DNA into the proteins that do most of the work in a cell is carried out by molecular machines made of a combination of RNA and protein.
  • It is the RNA, and not the protein, that does the critical work in this protein-making machine, which is called the ribosome.
    • The ribosome reads the sequence of the messenger RNA (mRNA) and, using the genetic code, translates the sequence of RNA bases into a sequence of amino acids.
  • The basic shape and functional core of the ribosome is formed by RNA.
  • Three general classes of RNA molecules are involved in expressing the genes encoded within a cell’s DNA.
    • Messenger RNA (mRNA) molecules carry the coding sequences for protein synthesis and are called transcripts;
    • Ribosomal RNA (rRNA) molecules form the core of a cell’s ribosomes (the structures in which protein synthesis takes place); and
    • Transfer RNA (tRNA) molecules carry amino acids to the ribosomes during protein synthesis.
  • During protein synthesis, an organelle called a ribosome moves along the mRNA, reads its base sequence, and uses the genetic code to translate each three-base triplet, or codon, into its corresponding amino acid.