Can we target the unchanging portion of virus’ genetic material?

Chris - What he's getting at is that some viruses change bits of themselves like the flu, changes its H genes (haemagglutinin genes) on the surface coat of the virus looks a little bit different. This is called genetic drift and this is down to genetic mutation when the RNA copies itself it makes mistakes and this translates into a slightly different structure for the virus. This is useful to the virus because it makes it look different so the immune system struggles to recognise it a second time.

Some bits of the virus do such a crucial job that they can't afford to change because if they did they would impair themselves. There are some un-variable bits of the virus that don't change. What he's asking is could we exploit that to make better treatments for viruses?

The answer is yes.

A good example is in flu itself. There was a recent study that was published in PNAS where researchers looked at the way in which a flu vaccine worked. Flu vaccines are based on the haemagglutinin coats on the virus. You make a coat on the virus, put it in a egg, you get some virus shrapnel and you can inject that into people. If you watch how the flu changes over time a vaccine that works against one type of flu might not work against another. If you get lots of examples of flu virus, compare the genetically you can find elements of the surface coat of the virus that have never changed over that time. If you make a vaccine out of that then in the case of the paper I'm referring to these people did it with a DNA vaccine. They just injected the DNA from that little bit of the virus coat. That hadn't changed and it was very effective against a broad repertoire of viruses so that might be a better way of doing it.

Another good example is HIV which has to bind onto CD4 receptors on our immune cells. If the virus were to mutate that bit of itself too much then it wouldn't be able to infect anymore because it wouldn't be able to recognise the target. Researchers are now looking at ways to specifically target the structure on the virus which the virus keeps very hidden but which doesn't change in order to block HIV.