Scientists from the Vaccine Research Center and the Laboratory of Infectious Diseases, part of the National Institutes of Health, have developed a new flu vaccination that is seen as a step toward combating all flu strains with a single vaccine.
In a study published online Aug. 24 in Nature Medicine, researchers reported they had developed a nanoparticle vaccine with a stabilized HA stem from an H1N1 influenza virus. The stem of the virus is less likely than the head to mutate, and the stem remains constant across different strains of flu within a particular hemoglobin group, according to background information on the National Institute of Allergy and Infectious Diseases website. The site said in theory, vaccines could be effective against future seasonal strains and give at least partial protection against future pandemic strains.
The new vaccine lacks the HA head region to more effectively stimulate antibodies that hitch themselves to the stem, according to the report.
In the study, researchers vaccinated mice and ferrets, then gave the animals lethal doses of H5N1 influenza. The vaccine elicited cross-reactive antibodies that completely protected the mice and partially protected ferrets against significant disease, according to the NIAID site. Even though the vaccine was created from an H1 HA stem, it did bring protection against H5, a different HA subtype.
Also, researchers reported, the vaccine did not elicit broadly neutralizing antibodies, but protection was shown to be antibody-mediated. Researchers injected antibodies from immunized mice into nonimmunized mice, and that protected the nonimmunized mice from a lethal dose of H5N1.
Together, the effectiveness of a vaccine derived from an H1 HA stem against an H5 base, along with the effectiveness of resulting antibodies in nonimmunized mice provide proof of concept that a vaccine that produces antibodies that target the HA stem can provide broad protection against diverse influenza strains.
According to the NIAID site, investigators may make additional refinements to the vaccine, will work on a similar approach against viruses with group 2 hemagglutinins, and will work toward a Phase 1 clinical trial to test the vaccine for safety and immunogenicity in humans.
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