The annual flu vaccine is an incredible tool to protect the most vulnerable (and many others) from recurrent disease. The virus’ danger lies in the ever-changing structures on the outer shell, requiring new vaccines every year to target them – but things might soon change.
A vulnerability has been discovered by researchers from The Scripps Research Institute, reported in the journal Nature. There is a section of the virus called the anchor that has not really been studied much – and it appears to be shared among many variants of the influenza virus. This has the potential to be exploited into a universal vaccine received once (or just a few times) rather than annually.
“It’s always very exciting to discover a new site of vulnerability on a virus because it paves the way for rational vaccine design,” co-senior author Dr Andrew Ward, professor of Integrative Structural and Computational Biology at Scripps Research, said in a statement. “It also demonstrates that despite all the years and effort of influenza vaccine research there are still new things to discover.”
The search for a universal vaccine has been going on for years, with some already in early clinical trials. The annual vaccine targets the head of hemagglutinin (HA), the most exposed and thus accessible part of the virus surface. This is also the part that is prone to mutation and pretty much changes yearly.
Universal vaccines candidates have been focusing on the stem of HA, a region that is less accessible and variable. This work looked at another region. By studying the blood of people who either had the vaccine or had been infected with flu, the team discovered a group of antibodies bound to the very bottom of the HA stalk, where it “anchors” itself to the influenza outer shell.
The team found 50 different antibodies that bind to this anchor. In lab tests, the antibodies were effective against many influenza strains – both seasonal like H1, and pandemic versions such as H2 and H5. In tests in mice, the antibodies delivered broad protection against different strains.
“By identifying sites of vulnerability to antibodies that are shared by large numbers of variant influenza strains we can design vaccines that are less affected by viral mutations,” says study co-senior author Patrick Wilson, MD. “The anchor antibodies we describe bind to such a site. The antibodies themselves can also be developed as drugs with broad therapeutic applications.”
These antibodies are produced naturally by our bodies. The goal for the vaccine is to elicit an immune response where the antibodies are produced in great quantities, making those who get the vaccine ready to fight the infection if they encounter it. The influenza virus infects 20 million people in the United States every year, and more than 20,000 people die because of it every year.