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Current Affairs

mRNA vaccine

Date: 18 November 2020 Tags: Miscellaneous

Issue

Moderna has announced results of human trials on the mRNA vaccine it has developed with US National Institutes of Health.

 

Details

  • The Moderna and Pfizer vaccines use the same technology, based on messenger RNA, or mRNA. Such vaccines make use of the messenger RNA molecules that tell the body’s cells what proteins to build.

  • The mRNA, in this case, is coded to tell the cells to recreate the spike protein of the coronavirus SARS-CoV-2, which causes Covid-19.

  • It is the spike protein that initiates the process of infection; it allows the virus to penetrate cells, after which it goes on to replicate.

  • A coronavirus vaccine based on mRNA, once injected into the body, will instruct the body’s cells to create copies of the spike protein. In turn, this is expected to prompt the immune cells to create antibodies to fight it.

  • These antibodies will remain in the blood and fight the real virus if and when it infects the human body.

 

Other vaccine method

  • Other types of vaccine include the non-replicating viral vector category. For example the vaccine developed by Oxford.

  • The vaccine uses a different virus, a weakened version of a common cold virus (adenovirus) that infects chimpanzees — to carry just the code to make the spike protein, like a Trojan horse.

  • The adenovirus, which has been genetically modified so that it cannot replicate in humans, will enter the cell and release the code to make only the spike protein.

  • The body’s immune system is expected to recognise the spike protein as a potentially harmful foreign substance, and starts building antibodies against it.

  • There is DNA vaccine that use genetically engineered DNA molecules that, again, are coded with the antigen against which the immune response is to be built.

 

mRNA

  • messenger RNA (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene and is read by a ribosome in the process of synthesizing a protein.

  • Transcription is when RNA is made from DNA. During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA as needed. 

  • mRNA is created during the process of transcription, where an enzyme (RNA polymerase) converts the gene into primary transcript mRNA (also known as pre-mRNA).