How do plants cope with Virus infections?

Emily - Well that's a really good question and there are some fundamental differences so viruses spread around animals mainly by lysing the cells and then they can go on and infect another one. Whereas they spread around plants via little pores called plasmodesmata. And so, one of the main ways that plants have to deal with viruses is by closing these plasmodesmata. They can use callows or they can use other proteins to block them off and stop them spreading, and they can also do this in the sieve tubes which are the connective tissues around the plant. But in a similar way to animals, plants can also respond to viruses with a hypersensitive response, so this is where the plant cells actually die. They sacrifice themselves and this is a good way of trying to stop the virus spreading. They don't have antibodies which is a big difference again with animals but some scientists are trying to engineer in 'plant bodies'. So for example, tobacco expressing antibodies to the co-protein of the grapevine fan leaf virus have been shown to be somewhat protected from infection by that virus. I think a very key way in which the plants deal with viruses is using small interfering RNAs and these target double-stranded RNA which is unusual in a normal plant cell, but a common thing to find if they're infected with the virus.

Chris - And that's quite similar to humans because Theo asks if it's the same in humans. Human cells also can detect when they have virus genetic material inside them usually because it doubles up and forms this double-stranded RNA and that triggers the cell to unleash a whole cascade of mechanisms that it uses to defend itself including killing itself and also, secreting factors called interferons that put other cells nearby on the alert, making them much less infectable.