The yearly influenza vaccine that health officials urge people to get each fall might also offer certain individuals some cross protection against the H5N1 virus commonly known as bird flu, according to investigators at St. Jude Children's Research Hospital.
The investigators found that the virus protein N1, one of two or more proteins present in the annual influenza shot, can act as a vaccine itself and trigger some cross protection against H5N1 in mice; and that some human volunteers already had antibodies directed against the same part of this virus.
"The jury is still out on whether the seasonal influenza vaccine is definitely a reliable way to offer people some protection from H5N1," said Richard J. Webby, Ph.D., assistant member in the Virology division of the Department of Infectious Diseases at St. Jude. "But our initial results suggest to us that this is a research trail worth following." Webby is senior author of the report that appears in the Feb. 13 issue of the online journal PLoS Medicine at www.plosmedicine.org.
The key to the apparent cross protection against H5N1 provided by the human influenza vaccine appears to be the antibodies produced in response to N1, a variety of the protein neuraminidase-one of the two proteins on the surface of the virus. While the amount of the other protein in the vaccine, hemagglutinin, or "H," occurs in large amounts, the amount of N1 can vary widely depending on the company that produces the vaccine.