US researchers identify new DNA weapon against avian flu

2008年09月19日

WASHINGTON, July 1 (Xinhua) -- By delivering vaccine via DNA constructed to build antigens against flu, along with a minute electric pulse, U.S. researchers have immunized experimental animals against various strains of the virus.

Researchers at the University of Pennsylvania reported that this is a potential new way to vaccinate against avian flu. The study was published in the latest edition of online journal PLoS ONE.

"This is the first study to show that a single DNA vaccine can induce protection against strains of pandemic flu in many animal models, including primates," says lead researcher David Weiner. "With this type of vaccine, we can generate a single construct of a pandemic flu vaccine that will give much broader protection."

Traditional vaccines expose a formulation of a specific strain of flu to the body so it can create immune responses against that specific strain. Conversely, a DNA vaccine becomes part of the cell, giving it the blueprint it needs to build antigens that can induce responses that target diverse strains of pandemic flu.

Avian flu mutates quickly, generating different strains that escape an immune response targeted against one single strain. "We are always behind in creating a vaccine that can effectively protect against that specific strain," notes Weiner.

Instead of injecting a live or killed virus, the research team injected three different species of animal models with synthetic DNA vaccines that are not taken from the flu microbe, but trick the immune system into mounting a broad response against pandemic flu, including strains to which the immune system was never exposed. Antibodies induced by the vaccine rapidly reached protective levels in all three animal species.

To ensure increased DNA delivery, the researchers administered the vaccine in combination with electroporation, a small, harmless electric charge that opens up cell pores facilitating increased entry of the DNA vaccine into cells.

If proven in humans, this research could lead the way to preparing against an outbreak of avian flu. Because these synthetic DNA vaccines are effective against multiple cross strains, vaccines could be created, stockpiled, prior to a pandemic, and thus be delivered quickly in the event of an outbreak, surmise the researchers.

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