Can one vaccine fight all flu viruses?

Mark
Written By Mark

New research led by Oregon Health & Science University in the United States has revealed a promising approach to developing a universal flu vaccine, with just one vaccine providing lasting immunity against a mutated virus.

The new vaccine

A study published July 17 in the journal Nature Communications tested a vaccine platform developed by Oregon Health and Science University against the virus considered most likely to cause a future pandemic.

The researchers reported that the vaccine elicited a strong immune response in monkeys exposed to the bird flu virus, but the vaccine was not based on the current bird flu virus. Rather, the organisms studied were vaccinated against the influenza virus that killed millions of people around the world in 1918.

“It’s exciting because in most cases this kind of basic science progresses incrementally, and it could be something in 20 years, and this could be an actual vaccine in five years or less,” said the study’s lead author, Dr. Jonah Sacha, professor and chair of pathology at the National Primate Research Center at Oregon Health & Science University.

Researchers reported that six of 11 monkeys vaccinated against the virus that circulated a century ago (the 1918 flu) survived exposure to one of the most deadly viruses in the world today. In contrast, a group of six unvaccinated monkeys exposed to the bird flu virus succumbed to the disease.

“If a deadly virus like avian influenza infects a human and sparks a pandemic, we need to quickly investigate and deploy a new vaccine,” said co-author Dr. Douglas Reed, associate professor of immunology at the University of Pittsburgh’s Vaccine Research Center.

Finding a fixed goal

The approach takes advantage of a vaccine platform previously developed by scientists at Oregon Health & Science University to fight HIV and tuberculosis, and is already being used in a human trial against HIV.

The method involves inserting small pieces of the targeted pathogen into a common herpes virus, cytomegalovirus, which infects most people in their lifetime, usually causing mild or no symptoms. The virus acts as a specially designed vector to stimulate an immune response from the body’s T cells.

This approach differs from common vaccines – including current flu vaccines – which aim to stimulate an antibody response targeting the latest form of the virus, which is distinguished by the arrangement of proteins covering the outer surface.

“The problem with influenza is that it’s not just one virus like coronavirus, it’s always evolving into the next version, and we’re always chasing where the virus is now, not where it’s going to be next,” Sasha says.

Spike proteins are on the outside of the virus to evade antibodies. In the case of influenza, vaccines are updated regularly using the best estimate of where the virus will go next. Sometimes that estimate is accurate, sometimes it’s not.

Instead, the virus’s internal structural proteins are targeted, rather than its ever-mutating outer envelope, by a specific type of T cell in the lungs known as effector memory cells. This internal structure doesn’t change much over time, providing a constant target for T cells to seek out and destroy any cells infected with old or newly mutated influenza virus.

Success Using a Century-Old Template

To test their T-cell theory, the researchers designed a CMV-based vaccine using the 1918 influenza virus as a template. In a Biosafety Level 3 laboratory at the University of Pittsburgh, vaccinated monkeys were exposed to aerosolized particles containing avian influenza virus, a highly specific virus currently circulating among dairy cows in the United States. The study raises the possibility of developing a preventive vaccine against avian influenza in humans.

“Inhaling airborne avian influenza virus causes a chain of events that can lead to respiratory failure,” said co-author Dr. Simon Barrat-Boys, professor of infectious diseases and microbiology and immunology at Pittsburgh. “The immunity induced by the vaccine was sufficient to limit viral infection and lung damage, protecting the monkeys from this very serious infection.”

By constructing more modern viral templates, the new study suggests that CMV vaccines may be able to induce an effective and long-lasting immune response against a wide range of new variants.