Baku, July 30 (AZERTAC). The first human antibody that can knock out all influenza A viruses has been shown effective in lab mice, an exciting step forward in the hunt for a universal vaccine, researchers said Friday.

The broadly neutralizing antibody, called FI6, could help vaccinate people against the flu without scientists struggling to piece together a new cocktail each season to match the often-changing strains.

Antonio Lanzavecchia, lead author of the study published this week in the US journal Science, described the finding as "significant," but noted it may be five years before it can be made into a widely available treatment.

"The antibody works not only by neutralizing the virus, which we knew, but also by recruiting killer cells to the virus-infected cells," Lanzavecchia, director of Switzerland`s Institute for Research in Biomedicine, told AFP in a phone interview.

"This suggests that once tested in a human system, the antibodies should work even better."

The antibody was found in plasma cells from a human donor. When given to mice heavily dosed with flu viruses, it was able to knock out the illness, offering hope for use as a remedy in people who get infected with the flu.

The discovery was made by using newly patented technology to screen hundreds of thousands of plasma cells in order to isolate the rare ones that produced the antibody.

"We are convinced that this is a very rare specificity but it is a very potent antibody," said Lanzavecchia, who is also chief scientific officer at patent-holder Humlabs. "The method was really the key to get this very rare antibody."

The antibody was tested in all 16 subtypes of A flu viruses and consistently worked against the often-changing hemagglutinin (HA), the protein that is on the virus`s surface. Mice and ferrets recovered from what would have otherwise been a lethal dose of flu virus when they were given the antibody within two days of infection.

The spread of A(H1N1), or "swine flu," killed at least 18,449 people and affected some 214 countries and territories after it was uncovered in Mexico and the United States in April 2009.