The study shows that it is possible to induce a long-lasting immune response against different types of influenza virus, including the historical 1918 influenza virus and the modern H5N1 virus.
The flu is caused by a virus that can cause serious illness. Fortunately, you can protect yourself every year by getting a flu shot. The problem is that this vaccination only protects against the flu viruses that are currently circulating, not against future variants. For this reason, the search has been underway for some time for a universal flu vaccine that can provide broad protection against different strains of influenza. Now it seems that the finish line is almost reached.
Variables
Scientists have been searching for a universal flu vaccine for years. It’s no surprise that developing one has been so difficult. “The problem with influenza is that it’s not a single virus,” explains researcher Jona Sascha. “Like SARS-CoV-2, influenza viruses keep evolving into new variants. As a result, we have to constantly try to keep up with the type of virus that’s active, rather than figuring out where the virus will mutate.” The spike proteins on the outside of the virus are constantly changing to prevent antibodies from recognizing and attacking them. So flu vaccines are regularly adjusted based on an estimate of how the virus will evolve. Sometimes this prediction is accurate, but sometimes it’s not.
new style
Traditional vaccines, like current flu shots, are designed to make the immune system produce antibodies against the latest version of the virus. These versions are distinguished by their specific protein structure on the outside of the virus. But researchers are taking a different approach for the universal flu vaccine. The new approach involves inserting small pieces of the targeted pathogen into the common cytomegalovirus (CMV). This virus infects most people without causing serious symptoms. CMV acts as a carrier designed to activate the body’s immune system, specifically T cells. These T cells focus not on the ever-changing exterior, but on the proteins inside the virus. These cells remain stable, allowing the T cells to find and destroy infected cells, regardless of whether the flu virus is old or newly evolved.
Exam
To test the T-cell theory, the researchers developed a vaccine using the 1918 influenza virus as a model. It went like this. In a secure laboratory, they vaccinated nonhuman primates and exposed them to tiny aerosol particles containing the H5N1 avian influenza virus. However, the vaccine was not based on the current H5N1 virus; instead, the primates received a vaccine against the 1918 influenza virus, which had caused many deaths worldwide at the time. Surprisingly, the vaccine produced a strong immune response. “If you inhale aerosolized H5N1 influenza virus, it can cause respiratory problems,” says researcher Simon Barratt-Boyes. “The vaccine protected the monkeys from infection and lung damage.”
100 years of evolution
Six of the 11 vaccinated primates eventually survived exposure to the virus, even after nearly a century of the virus’s evolution. That’s promising. “It worked because the internal proteins of the virus were so well preserved,” Sascha says. “Even after nearly 100 years of evolution, the virus couldn’t change those essential parts of itself.”
pandemic
The results show that the vaccine is not only effective in protecting non-human primates against H5N1, but also has the potential to be adapted for use against other mutated viruses, including possibly SARS-CoV-2. “For viruses that pose a pandemic risk, this is essential,” says Sascha. “We’ve focused on influenza, but we don’t know what will happen in the future.” Using newer virus models, the researchers believe that CMV vaccines could induce a strong, long-lasting immune response against many new variants of the virus. That’s not an unnecessary luxury. “If a dangerous virus infects humans and causes a pandemic, we need to quickly approve and distribute a new vaccine,” adds researcher Douglas Reed.
The new research reveals a promising approach to developing a universal influenza vaccine, one that needs to be administered only once and provides lifelong immunity against a constantly changing virus. The development of the new approach represents a significant advance in the fight against infectious diseases, with broader implications for future treatment and prevention of pandemic threats. Sacha sees the development as the latest step in the rapid advance of medical research to treat and prevent diseases. “This is exciting because this type of research usually progresses slowly; it usually takes around 20 years to achieve results. But this new vaccine could be available within five years. This means a huge change in our lives. We are clearly at the beginning of an innovative approach to infectious diseases,” he says.
