Here's a neat genetic trick: Make a chicken that can get the flu, but can't pass it on to other birds — or, presumably, to the humans who take care of them.

British researchers have done it.

The British team, with the support of a big poultry breeder and government funding, inserted a gene into chickens that blocks flu viruses from replicating. These genetically modified chickens can get infected. But their cells don't spew forth zillions of copies of flu viruses — so nearby poultry don't get sick.

In this I see a continuation of an arms race that began billions of years ago and, as Sean B. Carroll has pointed out, probably initiated the transition from simple to complex life. The flu viruses now have to come up with something new.