The RNA-based vaccine showed full protection in mice against the H5N1 strain circulating in US cattle.
RT’s Three Key Takeaways:
- Full Protection in Mice: An experimental RNA vaccine provided complete protection against the H5N1 strain circulating in US cattle when tested in research mice.
- Challenges in Cross Protection: The study revealed diminished protection when the vaccine was designed using older H5N1 virus components, suggesting the current H5N1 strain may evade immunity from older stockpiled vaccines.
- Platform Versatility: The repRNA/LION vaccine platform, previously authorized in India for COVID-19, is being advanced for clinical trials targeting other serious viral diseases.
An experimental vaccine designed against the highly pathogenic avian influenza H5N1 (HPAI H5N1) virus circulating in US cattle was fully protective in research mice in a new study published in Nature Communications.
National Institute of Allergy and Infectious Diseases (NIAID) scientists at Rocky Mountain Laboratories in Hamilton, Montana, led the animal study with colleagues from HDT Bio in Seattle who developed the replicating RNA vaccine (repRNA) platform.
Along with confirming that a single immunization with the experimental vaccine was effective against the new flu type in cattle (HPAI A H5N1 clade 2.3.4.4b), the study also allowed scientists to evaluate the vaccine method for “cross protection.” Would it work against the new virus if designed with components used in stockpiled vaccines from an older H5N1 virus (A/Vietnam/1203/2004)?
They found that when the test vaccine used a design from the older H5N1 virus, protection was diminished. The findings suggest that the HPAI H5N1 circulating in the US may be able to evade immunity from older H5N1 viruses.
Vaccine Platform Shows Promise for Multiple Viral Diseases
Scientists designed the repRNA vaccine to express the protective vaccine components, as well as the RNA replication machinery derived from an alphavirus. This allows for robust expression of the protective vaccine components upon delivery with LION, a proprietary nanoparticle formulation. The repRNA/LION technology is the basis of a vaccine that received emergency use authorization in India for COVID-19.
Additional applications of repRNA/LION are advancing toward clinical trials for other serious viral diseases after showing effectiveness against several different viruses in the lab.
Scientists at Rocky Mountain Laboratories and HDT Bio are continuing to develop the vaccine platform, and evaluations in animal models developed at Rocky Mountain Laboratories are ongoing.