This week, how information flows in the cell from DNA to proteins, and how scientists have tapped into this to enable a new way to make vaccines using messenger RNA.

For hundreds of years humans have triggered the immune system on purpose, in advance, to prepare it for deadly invaders. Smallpox, measles, typhoid, and today, Covid-19.

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We can trace the history of vaccination back to early days of smallpox inoculation - to China & India in the 1500s (maybe much earlier). They scratched matter from smallpox sores into the arms of people in an attempt to prevent future fatal infections. It was basic, but it was the start of a science saving millions of lives today. Over the years, vaccine technology has become more refined, and now, we have added one more way of making vaccines, using messenger RNA.

Information flow in the cell goes in one direction - from DNA to messenger RNA (mRNA) to protein. The genes in our DNA encode instructions to build the protein machines that make our cells function. DNA is the store of this information and is kept in a small compartment called the nucleus. The ribosomes, the cellular machinery that makes proteins, are found in the main part of the cell - the cytoplasm. Messenger RNA then is the intermediary, it is a temporary copy of genes from the DNA, which can move to the cytoplasm to be translated into a protein.

While previous vaccines have directly used dead or crippled virus or bacteria - or viral or bacterial proteins or toxins - to trigger an immune response, mRNA vaccines work on an elegant system of sending in a message containing instructions for the cell to make a specific protein. Once the cell makes this protein some of it is presented on the outside of its cell membrane for the scanning immune system cells to test. Once it is recognised as foreign it triggers an immune response - antibodies against the protein are created, meaning the immune system is primed and ready to go should infection ever occur.

When Pfizer BioNTech announced in November 2020 that their new mRNA vaccine against Covid-19 infection had shown success in its Phase 3 clinical trial it was certainly big news for a world gripped in a pandemic, but also a leap forward for this field of research. The Covid-19 vaccines made by Pfizer and Moderna are the first mRNA vaccines to be approved for public use…

Go to this episode on rnz.co.nz for more details