Human antibodies protect mice from bird flu

A group of international scientists, including researchers from the Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health, said: They used antibodies taken from immune cells of people survived recently after suffering from bird flu to successfully treat mice infected with H5N1 as well as protecting them from this deadly virus.

NIAID Director Dr. Anthony S. Fauci said: 'The possibility of the H5N1 virus or another influenza virus triggering a pandemic of global influenza because humans do not have natural immunity to fight, this is a major concern. of the global medical community. If this initial study is further confirmed by clinical trials and other labs, human monoclonal antibodies may be medically therapeutic and preventive interventions. important for pandemic flu. '

The study published in PLoS Medicine is a collaboration of three research groups: Dr. Kanta Subbarao and his colleagues at NIAID, Dr. Antonio Lanzavecchia and colleagues at the Institute of Medical Research in Bellinzona, Switzerland, and Dr. Cameron Simmons of the University of Oxford Clinical Research Unit at the Tropical Hospital in Ho Chi Minh City, Vietnam.

Four adult Vietnamese diagnosed with H5N1 during the period of January 2004 and February 2005 agreed to allow blood to be recovered after they recovered. In Switzerland, Dr. Lanzavecchia extracted antibody-producing white blood cells, also known as memory cells B, from these blood samples from Vietnam and was treated according to a process he developed so that they constantly created produce a large number of antibodies quickly.

Next, researchers at Dr. Subbarao's lab screened 11,000 samples containing antibodies provided by the Swiss team and found some antibodies that could neutralize the H5N1 virus. Based on this result, Dr. Lanzavecchia purifies memory cells B and eventually produces four monoclonal antibodies (mAbs) that secrete specific antibodies that can neutralize H5N1.

Dr. Subbarao and colleagues tested whether human H5N1 mAbs could protect mice from severe H5N1 infection. Many groups of mice, each of 5 mice received one of two types of H5N1 mAbs of people with 3 different doses or received human mAbs against diphtheria or anthrax. One day later, these mice were given the dose of H5N1 virus to the extent that they could cause death.

A monoclonal antibody in the mouse (Photo: ventanamed)

All mice in the control group - mice receiving H5N1-free mAbs - quickly became ill and died within a week. In contrast, all mice receiving the first H5N1 mAbs tested, regardless of dosage, were alive, while 80% of mice receiving the highest dose of H5N1 mAbs survived. Additional tests showed that mice receiving one of the two monoclonal antibodies that had a prophylactic effect had 10 to 100 times lower viral load in the lungs than the control mice, and had little or no virus. Which moves out of the lungs.

The researchers also tested whether the treatment of human H5N1 mAbs could be treated. They said the idea of ​​using blood from survivors after a long-lasting flu. For example, during the flu pandemic of 1918-1919, doctors recovered the patient's serum after getting the flu and injected it with new flu victims. Recent research results show that these blood transfusions, even when taken at the early stages of the disease, sometimes save the lives of patients.

In his study, Dr. Subbarao and his co-workers have caused groups of mice infected with a single dose of the H5N1 virus to die. The virus has been circulating in Vietnam in 2004. A total of 60 mice were given one of the four single antibodies of H5N1 within 24, 48 or 72 hours after being infected, while mice were A certificate for receiving mAbs does not contain a flu virus. All mice in the control group died within 10 days of infection, while 58 of the 60 treated mice survived. All 4 mAbs H5N1 have very strong protective effects. Dr. Subbarao said the most surprising thing was that the survival rate was amazing even when the treatment was delayed after 3 days.

Through these encouraging results, NIAID researchers have continued to test whether the H5N1 mAbs can be used to treat mice infected with a related H5N1 strain. Although the 4 mAbs used in the trial all came from the H5N1 virus of 2004, 3 of these 4 mAbs were able to protect mice from death when they received these three mAbs within 24 hours after they were infected with the H5N1 virus of 2005.

The researchers say this suggests that human mAbs may have a broad protective effect against mutated H5N1 viruses - this is a property researchers all yearn for in any material. measures that target flu viruses are always changing.

Dr. Subbarao said: In general, the findings from this international collaboration are very encouraging. They show that a sufficient monoclonal antibody of humans with the ability to neutralize H5N1 influenza virus can be quickly generated from the patient's blood, and these monoclonal antibodies work well. in treating H5N1 infection and preventing death from this infection in laboratory mice.

The authors plan to continue the study by increasing the production of mAbs H5N1 and if the technique is proven to be safe and effective in additional animal tests, they will consider using these mAbs of people in human clinical trials.

Hong Linh