A future flu pandemic may be fought by using the blood of those who have survived it. In the great flu of 1918, some doctors transfused the blood of survivors to those newly infected with the disease — and there is evidence that this halved the death rate.
Now research has shown that antibodies taken from the blood of patients convalescing from the H5N1 strain of avian flu — and then multiplied in the laboratory — can neutralise the infection, both in mice and in cultures of human cells.
The findings, from an international research team supported by the Wellcome Trust, indicate that such antibodies could be an important new weapon against an influenza pandemic.
At present, public health authorities would be reliant on antiviral drugs such as Tamiflu until a vaccine against the specific strain could be developed.
Antibody products made from the blood of recovering patients could be a valuable alternative, both for treating new infections and building immunity, scientists said. “We have shown that this technique can work to prevent and neutralise infection by the H5N1 bird flu virus in mice,” said Cameron Simmons, of the Oxford University Clinical Research Unit in Vietnam, a leader of the study team. “We are optimistic that these antibodies could also provide a clinical benefit to humans with H5N1 infections.”
For the study, published in the journal Public Library of Science Medicine, four Vietnamese adults who were infected with H5N1 between January 2005 and February 2006 agreed to donate blood. The samples were sent to Professor Antonio Lanzavecchia, of the Institute for Research in Biomedicine in Switzerland, who extracted white blood cells and treated them to produce large quantities of antibodies.
These were purified to create four different kinds of monoclonal antibodies — laboratory-made antibodies that are aimed at a single biological target, in this case different proteins from the H5N1 virus.
Researchers then tested the monoclonal antibodies on mice. Groups of five animals were given one of the antibodies in one of three different doses, while a control group was given human antibodies against diphtheria or anthrax. All the mice were then exposed to the H5N1 virus. The control mice developed flu and died within a week, while 80 per cent of those receiving the best of the monoclonal antibodies survived. The antibodies also appeared to be effective for treating H5N1 infections; 58 of the 60 mice treated with the antibodies survived.
Professor Lanzavecchia said: “We are encouraged by the broad neutralising activity of these antibodies and the moderate doses required.”
— Officials said that 36 people could have been in contact with bird flu after the outbreak in Corwen, North Wales. Eleven people had developed symptoms but no one was seriously ill. The strain identified was “very mild”, said the National Public Health Service. A dozen children aged 9 and 10 and two teachers are being given Tamiflu as a precaution.
Deadly strain
— A severe form of bird flu, H5N1, has affected poultry flocks and other birds in several countries since 2003
— 307 people have caught the infection as a result of close and direct contact with infected birds; 186 of these have subsequently died
— In birds, the influenza A viruses can cause a range of symptoms from mild illness and low mortality to a highly contagious disease with a near 100 per cent fatality rate
— As the virus can survive in contaminated droppings for long periods, it can be spread among birds, and to other animals, through ingestion or inhalation
— Migratory birds such as wild ducks and geese can carry the viruses, often without any symptoms of illness, and show the greatest resistance to infection. But domestic poultry flocks are particularly vulnerable to epidemics of a rapid, severe and fatal form of the disease.
source:department of health website TIMES.com
