The researchers reported two experiments, both using highly purified fragment antigen binding (FAB) molecules derived from equine antibodies to the H5N1 hemagglutinin glycoprotein. In the first, they showed that the equine (horse) antibodies prevented the infection of dog kidney cells. In the second experiment, the researchers showed that the equine antibodies prevented death from H5N1 flu in infected mice, which are known to be susceptible to the H5N1 flu. The mice were divided in to 4 groups. Each group containing 10 mice. The mice were infected with 50 microliters of H5N1 virus. After 24 hours three groups of mice were injected intraperitoneally with 50, 100, or 200 mcg of the antibody preparation. The fourth group, used as controls, received 200 mcg of normal horse sera. The H5N1 infection was fatal to all the control mice.
But seven of the 10 mice which were given 50 mcg of the antibody preparation and the mice that were given higher dosages survived. Dr. Lu and colleagues reported that this method can be used until an efficacious vaccine, specific anti-H5N1 agents, and effective epidemiologic control measures for H5N1 virus infection was discovered. Dr. Lu and colleagues concluded that H5N1-specific passive immunotherapy can be used for the early treatment of avian influenza patients to reduce the severity of illness and the likelihood of H5N1 transmission to others. But they also said that there is a major disadvantage as in these procedure polyclonal antibodies derived from horses has the potential to cause a strong host immune response which might inhibit its use in the clinic.
Bird flu is now found in populations in Asia, Africa, and Europe. Occasionally bird flu infects humans although it is not easily transmitted between people. But health authorities are worried that the virus has the potential to become a human pandemic disease with only small genetic changes. The World Health Organization confirmed 186 cases of human infection with the H5N1 strain, of which 105 have proved fatal.
