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The St. Jude study was the first one to show cross-reactive immunity against current H5N1 variants in ferrets, according to Robert Webster, Ph.D., a member of the Infectious Diseases department and holder of the Rose Marie Thomas Chair at St. Jude. Webster is an internationally renowned expert on avian influenza viruses and is senior author of the report in JID.

Cross-reactive immunity is the protection that a virus vaccine confers against not only the same virus, but also against variants of the original virus. "Such cross-protection would allow the use of a stockpiled vaccine until a vaccine against the specific variant causing the outbreak is developed," Webster said. "So our success with ferrets is extremely promising news."

Using reverse genetics, the team mixed genes from a safe, laboratory bird flu virus with a gene for the hemagglutinin (HA) protein from the H5N1 virus isolated in Hong Kong. The virus uses the HA proteins on its surface to infect cells in the respiratory tract. The resulting vaccine had the outside appearance of a dangerous virus that would stimulate the immune system, but the inside genes of a harmless variety of virus that could not cause disease. The St. Jude team was the first to use reverse genetics to make a vaccine against H5N1 that moved out of the laboratory and into clinical trials: http://www.stjude.org/media/0,2561,453_5484_4638,00.html.