Novavax Inc.’s virus-like particle (VLP) vaccine triggered a robust immune response and provided protection against the H9N2 strain of avian influenza, according to pre-clinical data published in the online edition of the journal Vaccine.
Novavax’s vaccine was tested in three animal models, including the ferret, which is the most predictive model for influenza vaccine effectiveness in humans.
Ferrets experience flu symptoms very similar to people who are infected with the virus. Protection, as measured by a reduction in viral load, was assessed in vaccinated ferrets challenged with live H9N2 avian influenza.
Like the H5N1 strain, the H9N2 strain initially spread among domestic poultry in Asia. Since then, it has been isolated from humans and is identified as having pandemic potential.
“This is the first time Novavax has measured the efficacy of our VLP vaccine against a live virus challenge in the very important ferret model,” said Dr. Rick Bright, vice president of global influenza programs at Novavax. The Company previously conducted live virus challenge studies with the H5N1 strain in mice. “These data are very encouraging because the ferret is a more predictive model for efficacy in humans.”
Virus-like particles mimic the three-dimensional structure of a virus but do not contain genetic material, so they cannot replicate or cause infection. As VLPs maintain functional properties of both influenza surface proteins (hemagglutinin and neuraminidase), they likely trigger multiple arms of the immune system to generate a broadly protective immune response.
Novavax has conducted several pre-clinical studies evaluating a number of its VLP vaccines against different strains of avian influenza. “All of the data we’ve accumulated to date indicate that our VLP vaccines have the potential to provide protection against various strains of avian influenza,” Dr. Bright said. “We are particularly encouraged by these ferret data and look forward to evaluating the immunogenicity of our H5N1 VLP vaccine in the clinic later this year.”
The study was conducted in collaboration with Dr. Terrence Tumpey of the Center for Disease Control and Prevention’s Influenza Division based in Atlanta, GA. As part of the study, Novavax also evaluated its proprietary Novasome adjuvant with both the H9N2 VLP vaccine and a recombinant hemagglutanin antigen vaccine. Both vaccines combined with adjuvant were shown to provide protection in mice. Adjuvants are used to improve the efficacy of vaccines and may help reduce the dosage required for protection in a pandemic setting.