A ‘super antibody’ against flu has been identified by scientists offering hope of a universal jab that could wipe out the infection.
The breakthrough is a major step forward in developing a long-term ‘cure’ rather than an annual winter vaccination.
The jab could also be used in severe infections or to protect hospital staff during an outbreak, saving millions of lives.
Scientists have identified three human antibodies which protect against the influenza B strain and one, called CR9114, which also protects against the more commmon and serious influenza A virus.
Structural biologist Professor Ian Wilson, of the Scripps Research Institute, La Jolla, California, said: ‘To develop a truly universal flu vaccine or therapy, one needs to be able to provide protection against influenza A and influenza B viruses, and with this report we now have broadly neutralizing antibodies against both.’
Referring to CR9114 Prof Wilson, whose findings are published online in Science Express, said: ‘It is the only one in the world that we know of that has been found to do this.’
He and co researchers at the Crucell Vaccine Institute in Leiden in the Netherlands generated a large collection of flu antibodies from the immune cells of volunteers who had been given a seasonal jab.
They then screened them to find those that could bind to a wide variety of influenza B viruses.
Three of the antibodies – known as CR8033, CR8071 and CR9114 – protected mice against normally lethal doses of the two major strains.
And CR9114 also fought off influenza A viruses, including the H1N1 subtype that killed about 17,000 people in a 2009 pandemic.
The researchers used state of the art scanning techniques to show that the antibodies, CR8033, CR8071, attach themselves to the ‘head’ of the hemagglutinin protein, which studs the outer surface of flu viruses preventing them from moving on from infected cells.
Dr Nick Laursen, a research associate in Prof Wilson’s laboratory, said: ‘The unique thing about these two antibodies is they neutralize flu viruses chiefly by preventing virus particles from exiting infected cells.’
Antibody CR9114 turned out to bind to a site on the hemagglutinin stem.
Study lead author Dr Cyrille Dreyfus, another member of Prof Wilson’s team, said: ‘It prevents the hemagglutinin protein from undergoing the shape-change needed for the virus to fuse to the outer membrane of a host cell.
‘This appears to be a real weak point of the virus.’
In a study published in 2009 Prof Wilson’s laboratory determined the structure of another antibody that broadly neutralizes influenza A viruses by binding to essentially the same site on the hemagglutinin stem but in a slightly different way so it fails to get a grip on influenza B.
Prof Wilson said: ‘With some tweaking of that antibody’s binding domains, we might have been able to get a broader effect like CR9114’s.’
Dr Jaap Goudsmit, of the Crucell Vaccine Institute, said: ‘As we move towards design of a universal flu vaccine, we need to find more inclusive assays to screen for antibodies such as CR9114, which may be highly effective but have novel mechanisms for neutralization that cannot be detected by the current methods used in influenza vaccine development.’