Horse Antibodies May Help Thwart Bird Flu

Scientists in China are turning to horses to help fight bird flu.

The researchers included Jiahai Lu, PhD, of Sun Yat-sen University in Guangzhou, China. They’re among experts worldwide working on bird flu treatments.

Writing in Respiratory Research, Lu’s team describes using parts of horse antibodies to fight H5N1, the virus that causes bird flu, in lab tests. The researchers don’t claim to have a fix for bird flu in people, but they see some potential in their horsey approach.

“Although various kinds of vaccines against H5N1 virus are under development, there is still a long way to go from bench to bedside,” write Lu and colleagues.

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Help From Horses

First, the scientists prepared H5N1 virus in hen’s eggs. Next, they immunized horses to make antibodies to H5N1.

Lu and colleagues took fragments of those antibodies, mixed them with H5N1 virus, and then spread the mixture on plates holding dog cells.

Dog cells were only exposed to H5N1 or the horse antibody fragments. For comparison, other dog cells were left alone, without either H5N1 or the horse antibodies’ fragments.

The researchers checked on the dog cells every day for the next five days. The dog cells exposed to both the horse antibody fragments and H5N1 didn’t die. But H5N1 took root and killed dog cells that were not treated with the horse antibody fragments.

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Tests on Mice

Next, the researchers tested the horse antibody fragments on young female mice infected with a lethal dose of H5N1.

The researchers split the mice into four groups. Twenty-four hours after the mice were infected with H5N1, three groups of mice got low, medium, or high doses of the horse antibody fragments. For comparison, the fourth group of mice got horse serum without any of the horse antibody fragments.

The mice were studied for the next two weeks. The results:

—The lower dose of horse antibody fragments brought 70 percent protection.

—The medium and higher doses brought 100 percent protection.

—The mice that got the horse serum without antibodies got no protection and all died.

”We have attempted to provide an alternate pathway of prevention and treatment of H5N1 infection, and in so doing, we hope that [horse antibody fragments] can play a potent role in combating the H5N1 virus,” write Lu and colleagues.

More work lies ahead. The horse antibody fragments haven’t been tested on people.

If successful, those fragments “may potentially be used for the early treatment of avian influenza patients to reduce the severity of illness and the likelihood of transmission to others,” write the researchers.

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By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Lu, J. Respiratory Research, March 23, 2006; vol 7. News release, BioMed Central.