Dr Laurence Tiley, University of Cambridge
Where would Easter be without chickens? There are something like 30 billion of them on Earth, and with these sorts of numbers, bird flu is a big concern. Not only can it wipe out a farmer's livelihood, it can also spread to humans and cause a pandemic. Biologist Laurence Tiley thinks he has the ideal Easter treat - a genetically modified hen that can't contract the flu bug. At the moment they're an alarming green colour, but he's working on that...
Laurence - Flu is a virus, which means itís a very tiny organism thatís completely dependent on infecting a cell and replicating within the cell of a host. Itís not like a bacteria, which it can sort of free-live. It has to actually get into an animal in order to reproduce itself. Flu causes disease in a lot of different species Ė horses, pigs, chickens are the ones that most people know about.
Chris - How much of a headache is flu for farmers of chickens?
Laurence - It can be a big headache. Strains that are, what we call highly pathogenic influenza viruses, they will kill 99% of a farmerís birds in a space of a couple of days. So, weíre trying to make strains of chickens that are intrinsically resistant to influenza or infection.
Chris - They can't catch flu.
Laurence - Thatís the ultimate goal, yes. Weíve made progress towards that. Weíve got birds that although they can still be infected, they donít pass the infection on to other birds.
Chris - How?
Laurence - By putting a new gene into the bird that produces something that throws a spanner in the mechanics of the virus. It cums up the ability of the virus to copy itself and transmit on from one cell to another. The virus has to copy itself in order to reproduce and be able to cause an infection and spread from one cell or one animal to another. The way it does that, it uses an influenza virus protein and enzyme that can copy and make new versions of its genetic material that it can then package up into new particles and those new viruses. So, weíve introduced something into the genome of the chicken that produces a small molecule that looks like a flu genome. When the virus infects those cells, it gets diverted into copying this little decoy rather than copying its own genome.
Chris - So, the virus infects the cell. Because youíve got your little thing that looks a bit like a virus component sitting in the genetic material of the cell, this also starts being copied. It side-tracks the cell into focusing on that rather than on making viable flu viruses in that cell.
Laurence - Thatís the theory behind, yes.
Chris - Have you actually done this yet? Have you got chickens that are making this molecule?
Laurence - Yes, weíve made chickens that have got a new gene inserted into them and that produces this particular molecule. Weíve tested them and shown that it does interfere effectively with the transmission of the virus from one bird to another.
Chris - Will this work for all of the different strains of flu because one of the things about flu is it comes in many different flavours? You hear about H1N1 and H3N2 in humans. Birds have maybe 17 of these different combinations, donít they? So, will your thing work against any type of flu that comes along?
Laurence - I think thatís the beauty of this particular approach that weíre taking is that the little bit of genetic material that weíre introducing looks like this piece of flu, is absolutely the same in all of those strains of flu. Itís a very, very important control element for the virus so there's very limited opportunity for it to evolve around it.
Chris - What about safety? Because people are very worried particularly in the wake of things like BSC, which is another example of things getting into the food chain that people would rather not had in the food chain. Is there any risk to the people who might eat these chickens?
Laurence - No. the nature of the molecule that weíve introduced into the chickens, itís not a protein for example. So, there would be no chance of anybody developing an allergy to it. The type of molecule it is would not be recognised by our immune system. It would have absolutely no effect on somebody who ate it and the chickens are producing this in every single cell of their body and they're absolutely normal, except that they're bright green because we use a fluorescent marker to track which ones are genetically modified and which ones aren't. Clearly, when it comes to the human food chain, we wouldnít be trying to flog fluorescent green chickens.
Chris - I donít know, a glowing green chicken might make quite a good marketing gimmick. That was Laurence Tiley from the University of Cambridge.