Researchers have advanced in the fight against bird flu by engineering antibodies that target the virus more effectively.
They claim to have found "a viral Achilles' heel" that could lead to the development of a flu vaccine.
The flu virus uses a "lollipop-shaped" spike known as hemagglutinin to invade nose and lung cells. The tip of the spike mutates continually, which means that flu vaccines must be redefined every year. The team have sidestepped this by finding a way to expose the non-mutating neck of the spike and selecting antibodies that can attach themselves to it. Once attached, the antibodies prevent the spike from injecting the virus's genes into human cells, rendering it unable to replicate.
Mice injected with the H5N1 virus were protected in 80 per cent of cases, and so promising is the work that the US-based National Institute of Allergy and Infectious Diseases has offered the team grants and access to its laboratory ferrets, which are vulnerable to bird flu.
But others are not so convinced. Henry Niman, a biochemist who tracks flu mutations, points out that human immune systems would have eliminated flu long ago if the virus had such a weak spot as the researchers are suggesting.
Their work — which is up to three years away from clinical trials in humans — was published in Nature Structural & Molecular Biology last week (22 February).