FLU: Universal vaccine still in sight

Lead author Dr. Jonah Sacha, chief of pathobiology at OHSU, envisions the vaccine being available in clinical practice “in 5 years or less.” With the new data, he reports that the candidate elicits a robust immune response in nonhuman primates exposed to a variety of influenza viruses, including the flu virus. H5N1 avian flu and the 1918 influenza virus.

The study thus shows that:

• 6 of 11 nonhuman primates vaccinated against the virus that circulated a century ago survive exposure to one of the deadliest influenza viruses in the world today, H5N1;
• However, six unvaccinated primates exposed to the H5N1 virus succumbed to the disease.

A promising vaccine platform: Broader implications of this new platform could emerge, with the development of new vaccines against other mutating viruses with pandemic potential, including SARS-CoV-2. The approach indeed exploits a vaccine platform previously developed by the same team to fight HIV and tuberculosis, and is currently being used for a clinical trial of an HIV vaccine.

The technique involves inserting small pieces of target pathogens into the cytomegalovirus of the common herpes virus, or CMV, which infects most people during their lifetime and usually produces mild or no symptoms. The virus acts as a vector to induce an immune response from the body’s T cells. This approach differs from that of common vaccines, including existing flu vaccines, which are designed to induce an antibody response targeting the most recent evolution of the virus, characterized by the arrangement of the virus’s outer surface proteins.

The new approach targets the inside of the virus,

• and thus addresses the challenge of evolving spike proteins on the outer surface to evade antibodies;

• A specific type of T cell in the lungs, called memory effector T cells, targets the virus’s internal structural proteins, rather than its continually mutating outer shell; an internal structure that remains fairly stable over time and provides a relatively fixed target that can be spotted and destroyed by these T cells.

“Our approach works because the internal protein of the virus is preserved. So much so that even after almost 100 years of evolution, the virus has not modified these components that are crucial for its survival.”

By synthesizing more recent virus models, the new study suggests that these candidates would be able to generate an effective and lasting immune response against a wide range of new variants.

“There is no doubt that we are on the cusp of the next generation of vaccines against these emerging infectious diseases.”