• Question: Do you make the virus make people better by altering its genetic code and structure?

    Asked by u12mussont to Rachel on 19 Nov 2013.
    • Photo: Rachel Dakin

      Rachel Dakin answered on 19 Nov 2013:

      Hi u12mussont – good question, that’s exactly what we do 🙂
      A good few years ago scientists discovered the genetic code of the adenovirus (the virus I work on). From this they could work out which bits coded for the proteins making up the viral structure and which bits held the genes responsible for replication or copying of the virus. It is not the presence but the replication of the virus which actually causes viruses to make us sick. Scientists found if they removed the DNA which had the code for the replication genes they could still make a functioning virus but it could no longer copy itself. This is key for the use of viruses as delivery men – they still function as viruses so are great at attaching to and getting inside cells but because they can’t copy themselves they don’t make us sick. In addition to removing the genes responsible for replication we can add a gene that will be therapeutic. This just means it will help stop or slow the progression of a disease.
      In answer to changing virus structure this is something we do as well, something I’m doing right now actually. Viruses have different destinations depending of their ligands and the receptors on the cells. This is a bit like keys and locks – different viruses have different keys and different cell types have different locks. Some viruses might bind receptors in the liver whilst others might bind in the lung. We can alter the structure by taking out a gene that codes for 1 part of the virus structure and replacing it with the gene from another virus. So I might remove the DNA sequence which makes a protein that binds to liver and replace it with the DNA sequence from another virus which I know makes a protein that binds to lung.
      I want to make my virus bind to the blood vessel as well as possible so I’m looking at changing its genetic code to remove DNA sequences which will cause the virus to bind to other parts of the body and add DNA sequences that will help it to bind to the blood vessels.

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