What is Gene Sequencing?

Every living organism has a unique ‘instruction manual’ to build and run the organism, a copy of which is contained in every cell. When we sequence the genes of an organism we are ‘reading’ this instruction manual.  The instructions are contained in a substance called nucleic acid. For humans, this is deoxyribonucleic acid (DNA), but for some viruses, like the coronavirus which causes COVID-19, the instructions are coded in a very similar substance called RNA.  In the same way that words are composed of letters in different combinations, the DNA or RNA molecules have sequences of molecules called bases. In DNA these are adenine, guanine, cytosine, and thymine (A, C, G, and T) and in RNA the thymine is replaced by Uracil (U). When we sequence a bacteria or virus we are looking at the order of these bases and comparing them with other strains of the organism.

Gene sequencing can tell us many important things about organisms- how they are related to each other, how they are changing over time, and for viruses and bacteria that cause diseases, sequencing can tell us which are the best drugs to use in the treatment or help us to discover new treatments and vaccines.

In the Epidemic Intelligence project, we will sequence samples of the SARS CoV-2 virus which causes COVID-19 to understand how the characteristics of the virus are changing over time. This will help us to develop new ways to diagnose, treat and prevent the disease.