A study released this weekend in the journal Nature Structural and Molecular Biology reports researchers have discovered human antibodies that defend against several strains of the flu including the avian (bird) flu, the 1918 pandemic flu, and common seasonal flu strains. The discovery could lead to the development of vaccines that protect against several flu strains, eliminating the need for seasonal flu shots. More immediately, the antibodies might be used to confer protection against a flu pandemic.

Researchers found the naturally-occurring antibodies – proteins produced by the immune system to protect against invading bacteria and viruses – by screening a huge number of flu antibodies collected from the blood of volunteers. It is unknown how common the antibodies are in the general population. They tested the antibodies in mice and found that they were effective in neutralizing the common seasonal flu known as H1N1, the H5N1 avian flu, and the virus responsible for the 1918 "Spanish flu" pandemic that killed nearly 50 million people worldwide.

What makes the newly discovered antibodies special is that they bind to a place on the surface of the flu virus that does not mutate or change often. Other portions of the influenza virus surface, including the two major surface proteins known as hemagglutinin (H) and neuraminidase (N), mutate frequently to evade detection from the immune system. Current flu vaccines are directed against these ever-changing proteins, making them good for only one season because the virus changes its surface proteins enough to make the existing antibodies useless. This mechanism also means that flu shots often provide less-than-optimal seasonal protection because changes in these proteins can occur so rapidly that the antibodies produced in response to the vaccine no longer recognize the virus.

Since the new antibodies are made by human cells and are monoclonal, meaning that they are all directed against the same portion of the flu virus, the researchers believe that clinical trials testing their use could be started soon. Other types of human monoclonal antibodies are already in use to treat some types of cancer. If the trials are successful, injection of the monoclonal antibodies could provide protection against multiple flu strains for high-risk individuals such as health care workers, and may also be used to treat those who already have the flu. In the future, the researchers will try to isolate the portion of the flu virus that these antibodies target and use it to make vaccines that could be used to protect everyone against multiple flu strains.

For more information on vaccines, see the Healia Health Guide on Vaccines. If you have questions about the flu, ask it in the Healia Health Community for Cold and Flu.

_{Photo: samantha celera, Flickr, Creative Commons}