April 18, 2008
Scientists Attempt To Mutate Bird Flu Vaccine
Scientists are working to develop a next-generation bird flu vaccine that could potentially protect against mutations of the virus.
One experimental vaccine already seems to be returning positive results. The vaccine fuses a common cold virus and parts of DNA from the H5N1 virus. U.S. researchers reported that the vaccine appears to stimulate an immune response in mice.
"We want to have a vaccine that can be stored in advance and have the potential to provide protection for a period of time until we can change the vaccine to match the latest form of avian influenza," said Suresh Mittal of Purdue University in Indiana, who worked on the study.
"The combination of flu genes that we've used to produce the vaccine, I think, will provide that capability."
Although, the H5N1 avian influenza virus rarely infects humans "“ only 381 have been infected since 2003, it is rampant among flocks of birds in Asia, Africa, and some parts of Europe.
At least 16 companies are hoping to create a successful vaccine that would prevent bird flu infection in people, while having the ability to mutate each year.
If a pandemic broke out today, it would take almost one year before vaccinations would be available, because current technology requires flu vaccines to be grown in chicken eggs.
Mittal, Mary Hoelscher of the U.S. Centers for Disease Control and Prevention and colleagues worked with H5N1 virus samples from Vietnam and Indonesia to make a vaccine that they hoped would work against even "drifted," or mutated, strains.
They used a common cold virus, known as an adenovirus, to carry H5N1's hemagglutinin gene, which give flu strains the "H" of their names.
Most current flu vaccines also focus on hemagglutinin.
So far the researchers have only tested mice, but the vaccine caused a strong immune response that lasted at least a year.
"In humans we want a vaccine to be fully effective for at least a year," Mittal said.
"This approach may prevent severe illness and death or shorten the course of future infection with H5N1 virus strains that are antigenically distinct from currently circulating strains, and it may offer stockpiling advantages that overcome the limitations associated with storage of egg-derived vaccines," the researchers wrote.
Their technology has been licensed to PaxVax Inc.
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Centers for Disease Control and Prevention