WASHINGTON The human body makes rare antibodies effective against all flu viruses and these might be boosted to design a better universal flu treatment, researchers reported on Monday.
Tests on mice suggest these immune system proteins could help most people survive a normally lethal dose of flu virus, the team at the University of Wisconsin and Seattle-based Theraclone Sciences said.
"The ability of these antibodies to protect mice from highly lethal strains of influenza is encouraging," said Yoshihiro Kawaoka, a flu expert at the University of Wisconsin-Madison and University of Tokyo who worked on the study, said in a statement.
"Such antibodies may be especially useful during outbreaks of newly emerging, highly pathogenic influenza viruses."
H1N1 swine flu is still spreading globally, having caused the first pandemic of the 21st century. While it is a relatively mild strain, it has killed far more children and young adults than flu usually kills and could easily mutate into a more virulent form.
Regular seasonal flu does its own share of damage, killing 250,000 to 500,000 people globally in an average year, according to the World Health Organization.
And new strains could move into the human population any time -- including the highly lethal but still rare H5N1 bird flu, which has killed 295 of 499 people infected since 2003.
Privately owned Theraclone identified the antibodies using a technology it has to screen for rare but useful antibodies. The company then contracted with the researchers to make large quantities of these antibodies and test them in mice.
The antibodies attack a part of the flu virus that all or most strains seem to have, without a lot of mutations.
Writing in the Proceedings of the National Academy of Sciences, the researchers said when they infected mice treated with the antibodies with deadly doses of H1N1 and H5N1 flu, 60 percent to 80 percent recovered, compared to just 10 percent of untreated animals.
It may be possible to engineer better versions of the antibodies in the lab -- so called monoclonal antibodies -- to make a good alternative treatment for dangerous flu infections, the researchers said.
Four drugs are currently on the market to treat flu -- Roche AG and Gilead Sciences Inc's Tamiflu, GlaxoSmithKline and Biota's Relenza, and the two older drugs amantadine and rimantadine.
But flu viruses almost all resist the effects of the older drugs and several strains of seasonal flu have mutated into forms that cannot be helped by Tamiflu. And Relenza and Tamiflu must be given within the first two days of infection to be really helpful.
So scientists are looking for new and better treatments.
Theraclone signed an $18 million deal with privately held Zenyaku Kogyo of Japan to find and produce such antibodies last year.
(Editing by Todd Eastham)