Scientists have hailed a breakthrough in the search for a universal flu vaccine after discovering a new antibody that attacks viruses year after year.
A vaccine capable of working against all strains would save lives and money by eliminating the need for annual inoculations.
Researchers in California and Holland said they are a "step closer" to meeting this objective in a study published in the journal 'Science Express'.
By putting the new antibody together with one they discovered two years ago, they hoped to make a vaccine against the vast majority of strains.
They said that not only would it stop people catching a virus, but also neutralise it in those already infected -- extremely useful in a situation such as the swine flu pandemic of 2009.
Ian Wilson, a professor at the Scripps Research Institute in California, said a vaccine containing the antibodies had "the potential to protect people against most influenza viruses".
Both antibodies work by binding to small, unchanging sites on the "envelopes" that covered flu viruses. These protective layers were studded with proteins that attracted the attention of the body's immune system. This left the virus to spread unimpeded.
What made flu viruses particularly tricky was that these proteins evolved rapidly, so a vaccine that worked one year might be redundant the next.
However, scientists from Scripps and Crucell, a Dutch pharmaceutical company, found that viruses also contained common elements. Antibodies that locked on to these "binding sites" -- called epitopes -- should be able to work year in, year out.
Two years ago, the team identified the antibody CR6261, which, in mice, had been proven to work against half of flu viruses, including the H1 family.
Now they have found another antibody, CR8020, which appeared to work against H3 and H7 strains. Human trials of a vaccine based on the former were due to start soon.
Prof Wilson said that the antibodies could be put into a combined vaccine that acted asa "fast-acting therapy" against epidemic or pandemic strains.
"The goal is an active vaccine that elicits a long-term antibody response against those vulnerable epitopes," he said. (© Daily Telegraph, London)