Bird flu vaccine works on mice

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HONG KONG, March 1 (UPI) -- A modified vaccine once used to treat smallpox has proven effective in treating mice infected with the deadly H5N1 bird flu strain, Hong Kong researchers say.

While human trials are at least two years off, the University of Hong Kong scientists, who worked with U.S. researchers, say the vaccine holds the potential to become a ''safe and effective vaccine that can be rapidly deployed for pre-exposure vaccination of millions of people," Kyodo news service reported Sunday.

The World Health Organization says at least 256 of the 408 people in 15 countries who have contracted the H5N1 bird flu since December 2003 have died. Scientists fear the strain could cause a global epidemic.

The scientists in Hong Kong said Sunday their study, published in the latest edition of the Journal of Immunology, showed a 100 percent survival rate among infected mice treated with the vaccine, Kyodo said. Researchers from the U.S. National Institutes of Health also participated in the study.

''What we have shown is a novel strategy for vaccinating against H5N1,'' Hong Kong microbiologist Malik Peiris told reporters.

He noted the modified vaccine is safe and economical. The new vaccine, called Wyeth/IL-15/5Flu, has three main elements -- a licensed vaccinia virus; human interleukin-15, a regulatory protein used to boost immune response; and five genes from H5N1.

''We have shown from our studies that it produces good and very quick immune responses even with a single dose," he said. "This is a very important advantage because when the pandemic comes, we don't have too much of time."