"By using an existing pandemic flu strain, this research will provide the basis for design of alternative vaccines against influenza viruses with enhanced virulence," says Dr. Tumpey.
Although the researchers are not discounting the potential role T-cells may have in combating flu viruses, they concluded that in this study, the experimental DNA vaccine protected the mice by stimulating antibodies capable of neutralizing the 1918 flu virus.
"Who would have imagined five years ago that we'd be able to create a vaccine that protects against one of the deadliest forms of influenza the world has ever seen?" adds Dr. Nabel. "It's because the 1918 flu virus has been reconstructed that we are now able the further understand it. Hopefully, this virus will help us to develop effective vaccine strategies for current pandemic influenza virus threats."
To evaluate the vaccine's antibody-inducing capabilities while minimizing exposure of lab personnel to the 1918 flu virus, Dr. Nabel and his VRC colleagues also created artificial viruses, or pseudoviruses, featuring the HA of the 1918 flu virus but stripped of the ability to cause infection. The pseudoviruses were then incubated with antibody-containing blood samples from the mice immunized with the DNA vaccine and those that were not. The researchers found that the antibodies from the immunized mice neutralized the pseudoviruses while the blood samples from the mice that were not immunized had no effect. This method was also effective in identifying neutralizing antibodies to the H5N1 avian flu virus and could be used to screen for monoclonal antibodies that may be used as an antiviral treatment, according to Dr. Nabel.
Source:NIH/National Institute of Allergy and Infectious Diseases