Blood of bird flu survivors promises new treatment for the deadly virus

Scientists are optimistic that blood donated by four survivors of bird flu will offer some clues as to why some people appear to have protection against the deadly H5N1 virus.

Scientists suspect that the blood of the bird flu survivors may harbor a potent protection against the lethal virus and by culling immune-system molecules from that blood a new therapy for the virus could be developed.

An international team of researchers say they may have the first evidence from tests in mice, that this method may in reality work.

If they are right and the research succeeds it could then be possible to stockpile these antibodies to be used as an additional method of treating or even preventing the H5N1 virus mutating and sparking a worldwide epidemic.

Dr. Anthony Fauci, an infectious disease expert at the National Institutes of Health, says the potential is both interesting and exciting.

The research was prompted when four Vietnamese adults who survived bouts of H5N1 in 2004 agreed to donate blood to the Hospital for Tropical Diseases in Ho Chi Minh City.

Dr. Antonio Lanzavecchia at Switzerland's Institute for Research in Biomedicine, then came up with a way to cull the antibody-producing cells from the blood and keep them churning out the molecules in laboratory dishes.

This in turn led to the NIH's Dr. Kanta Subbarao testing thousands of those antibodies in order to isolate the few able to kill H5N1; these were then purified to better target the virus.

Then the real world entered the equation when Dr. Subbarao infected mice with H5N1 virus; some were given the antibodies before they were exposed, others after they were already infected; and others were given antibodies that target different diseases, but not influenza.

This resulted in the mice given the non-H5N1 antibodies dying, while the H5N1-targeting antibodies protected the other mice, both when they were administered as a vaccine-like preventive or after infection.

Of even more importance was that they worked against both the same 2004 strain that the people had survived and against a different H5N1 strain that circulated in 2005.

The technique called "passive immunotherapy," is not new and has been used before to protect against certain viruses such as hepatitis A vaccines when antibody-containing shots were common for tourists heading to developing countries.

The scientists however say more work is needed before these purified antibodies are tested on people.

The H5N1 strain has in one way or another, killed millions of birds across the globe and according to the World Health Organisation, there have been 306 known cases in humans, of which 185 have been fatal.

The research is published in the online journal PLoS-Medicine.