The first antibody that could knock out all influenza A viruses has been isolated and tested in mice, offering a new path forward in the hunt for a universal vaccine, researchers said Friday. The broadly neutralizing antibody, called FI6, was taken from human plasma cells. When tested in lab animals heavily dosed with flu viruses, it was able to knock out the illness, offering hope for both therapeutic and vaccine uses. British virologist John Skehel, at the Medical Research Council\'s National Institute for Medical Research at Mill Hill, said the find may eliminate the need to combine different antibodies into a single shot against the flu every season. The antibody was tested in all 16 type A flu viruses and consistently worked against the often-changing hemagglutinin (HA), the protein that is on the virus\'s surface. \"In terms of designing a vaccine the main advantage of this completely cross-reactive antibody is that you can focus on the region of HA recognized by one antibody, rather than having to piece together structures from different antibodies,\" Skehel told AFP. \"In terms of therapeutic use, progress may be quicker, and will move towards clinical trials of the antibody very similar to those required before use of anti-viral drugs.\" Flu pandemics are unpredictable, and millions of people around the world are infected annually with seasonal flu varieties that can be lethal in people with weak immune systems, including children, the elderly and pregnant women. 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. The World Health Organization declared a pandemic on June 11, 2009. The event was formally over on August 10, 2010. Lead study author Antonio Lanzavecchia, director of Switzerland\'s Institute for Research in Biomedicine, said the \"unpredictability of new pandemics highlights the need for better treatments that target all influenza viruses.\" \"As the first and only antibody which targets all known subtypes of the influenza A virus, FI6 represents an important new treatment option and we look forward to taking it through to the next stage of development.\"