Monkeying around with HIV

Young Rhesus MacaqueI have just got back from co-organising a science workshop in Lausanne, Switzerland. It was great fun, I thoroughly enjoyed many of the talks. And as an organiser it made me happy to see the scientists enjoying the talks then realising that they can use these ideas in their own work. Some of the attendees who met at the meeting for the first time were even talking of teaming up and working together. If they do, it’ll put a smile on my face that I have helped that.

One of the talks I particularly liked featured the rhesus macaque monkey. It was by Ed Campbell from a university in the USA. About 20 or so years ago people realised that the rhesus macaque was immune to infection by HIV, the virus that causes AIDS. This prompted a scramble to work out why. The HIV scientists wanted to learn from this monkey how to resist HIV. It turns out that it is due to a protein called TRIM5α (this is a bit of a funny name, but that is not important). The viral particles can get into the cells of rhesus macaque monkeys but, through a still poorly understood mechanism, TRIM5α somehow trashes these viral particles before they can start taking over the cell.

So then the scientists thought maybe we don’t have a TRIM5α protein. But we do, it just doesn’t work against HIV. But it is so so close, TRIM5α is a protein, and these are polymers of hundreds of amino acids joined one after another. If the three hundred and thirty second amino acid is changed from an arginine to a proline, then it attacks HIV.

Evolutionary biologists have studied this, and this part of the TRIM5α protein has evolved at a blistering pace over the last few million years. There is evidence that our TRIM5α version evolved to fight off a virus from the same class of viruses as HIV, a few million years ago. But unfortunately, although our TRIM5α evolved to be great at fighting that now dead virus it did so at the cost of being pretty useless at fighting HIV. An evolutionary example of out of the frying pan and into the fire.

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