Researchers from Britain and Switzerland used a new method aimed at beating "needle-in-a-haystack-type-odds" and managed to identify an antibody from a human patient which neutralizes both main groups of influenza A viruses.
Although it is an early step, they said, it is an important one and in time may pave the way for the development of a universal flu vaccine.
Vaccine makers currently have to change the formulations of their flu shots every year to make sure they protect against the strains of the virus circulating. This is a cumbersome process which takes time and money, so the goal is come up with a universal flu vaccine that could protect people from all flu strains for decades, or even for life.
Dozens of companies make influenza vaccines, including Sanofi, GlaxoSmithKline, Novartis, AstraZeneca and CSL.
"As we saw with the 2009 pandemic, a comparatively mild strain of influenza can place a significant burden on emergency services. Having a universal treatment which can be given in emergency circumstances would be an invaluable asset," said John Skehel of Britain's National Institute for Medical Research, who worked on the study with colleagues from the privately-owned Swiss firm Humabs.
Antonio Lanzavecchia, Humabs' chief scientific officer and director of the Swiss Institute for Research in Biomedicine, said high rates of seasonal flu and the unpredictability of possible future pandemics underlined the need for better treatments that target all flu viruses.
When someone is infected with the flu virus, their antibodies target the virus' hemagglutinin protein, the researchers explained in their study, which was published on Thursday in the journal Science.
Because this protein evolves so rapidly, there are currently 16 different subtypes of influenza A, which form two main groups. Humans usually produce antibodies to a specific subtype, and new vaccines are made each year to match these strains.
To make progress toward a universal shot that could be used every year, scientists need to identify the molecular signatures that prompt the development of broadly neutralizing antibodies.
Previous research work has found antibodies that work in Group 1 influenza A viruses or against most Group 2 viruses, but not against both.
This team developed a method using X-ray crystallography to test very large numbers of human plasma cells, to increase their odds of finding an antibody even if it was extremely rare.
When they identified FI6, they injected it into mice and ferrets and found that it protected the animals against infection by either a Group 1 or Group 2 influenza A virus.
"As the first and only antibody which targets all known subtypes of the influenza A virus, FI6 represents an important new treatment option," Lanzavecchia said in a statement.
Researchers in the United States said last year they were having some success with another possible approach to developing a universal flu shot, using a two-step system of a vaccine using DNA to "prime" the immune system and then a traditional seasonal flu shot.
SOURCE: bit.ly/pGCtyR Science, online July 28, 2011.