This finding, coupled with results of previous studies that showed protection against multiple human influenza strains, suggests that such a vaccine would protect humans against multiple variants of the bird and human influenza viruses, according to Richard Webby, Ph.D., assistant member of Infectious Diseases at St. Jude. Such a vaccine could protect humans against an H5N1 "bird flu" virus that mutates so that it adapts to humans and can readily spread from person to person, Webby said. Flu experts and public health officials fear that such an H5N1 variant would trigger a human pandemic (worldwide epidemic).
Webby is scheduled to present the findings of this study at the U.S. Public Health Service Professional Conference in Denver, Colo., May 3 at 12:30 pm EDT.
The investigators used two versions of Vical's multi-component, DNA-based vaccine in the studies. One vaccine was directed against three viral proteins: NP and M2, which are "conserved" proteins that generally do not mutate quickly and therefore, are slow to avoid immune responses triggered by the vaccine; and H5, a "variable" protein on the surface of the bird and human flu viruses that is critical to their ability to infect cells. This variable protein is known to mutate readily, thereby foiling previous immune responses it triggered--whether due to natural exposure or vaccination. The other version of the vaccine contained only the two conserved viral proteins.
In the St. Jude study, the full, three-component vaccine (H5, NP and M2) provided complete protection in mice against lethal challenges with a highly virulent (Vietnam/1203/2004) H5N1 avian influenza virus. Moreover, other studies sho
Source:St. Jude Children's Research Hospital