A team of researchers from the United States have found that an antibody that “embeds” influenza virus surface proteins can protect mice from a variety of influenza virus strains and is expected to be developed as a universal influenza vaccine in the future.

Hemagglutinin (H protein) and neuraminidase (N protein) are two proteins on the surface of influenza virus, which divide influenza virus into different subtypes. At present, the influenza vaccine is mainly targeted at hemagglutinin. In the winter of 2017, Ali Ellibidi, an assistant professor of Pathology and Immunology, University of Washington, found that the blood samples of a flu patient contained antibodies that target not only hemagglutinin but also other proteins.

Ellibidi sent three of the unidentified antibodies to Icahn School of Medicine at Mount Sinai for testing. Florian Kramer, a professor of Microbiology at the school, found that one of the antibodies, known as 1G01, blocks almost all known neuraminidase activity in a variety of influenza virus strains. Kramer’s team infected mice with lethal doses of the flu virus and found that the antibody could fight 12 tested flu strains. These include three types of human influenza viruses, avian influenza and other strains that are not transmitted from person to person. It was also found that even if the mice were injected with antibodies 72 hours after infection, all the mice survived. By contrast, another flu drug, Tamiflu, must be administered within 24 hours of symptoms.

Ian Wilson, a structural biologist at the Scripps Research Institute in the United States, analyzed the structure of the antibody and found that the antibody inserted a circular structure into the active site of neuraminidase, which prevented neuraminidase from releasing new viral particles from the cell surface. At the same time, studies have shown that this antibody only blocks the active site of neuraminidase, while this active site between different influenza strains will not change, so it is effective against a variety of influenza viruses. Researchers are currently designing new flu drugs and vaccines based on antibody 1G01.

The results of the study were published in the Science.