Two teams of virologists found themselves at the heart of bioterrorism maelstrom late last year when their studies on mutant bird flu were suppressed by US authorities.

While security experts feared the reports were recipes for bioweapons of mass destruction, the researchers argued they held important lessons for the threat of natural flu pandemics developing in the wild.

Now the authorities have backed down and the reports have been released. Kevin Fong hears how tiny variations in the genes of bird flu can completely change the behaviour of the pathogens and he asks whether deliberate genetic manipulation in the lab can replicate the natural genetic variations occurring in farms around the world.

In 2009, the new strain of H1N1 flu emerged from a few villages in Mexico to infect the world in weeks. What experts fear is that a simple genetic change to H5N1 bird flu could allow it to spread as fast, but with far deadlier consequences. They argue that by identifying dangerous variants in the lab first, we'd be better prepared with vaccines ahead of the danger.

Producer Roland Pease.

(Image: A coloured transmission electron micrograph of the H5N1 virus, better known as bird flu. Credit: Science Photo Library)