Protective antibody discovery could lead to better flu treatments

Influenza viruses, like the model shown here, display several kinds of surface proteins on their exteriors (credit: NIAID).

A newly identified set of three antibodies could lead to improved treatments and vaccines against influenza, said researchers. They found that the antibodies, which bind to neuraminidase (NA) proteins on the surface of influenza viruses, provided broad protection against several different strains of influenza when tested both in vitro and in mice.

Most influenza vaccines are designed to stimulate an immune response against the hemagglutinin (HA) protein found on the surface of the influenza virus. However, HA proteins change frequently as the virus evolves. NA proteins change more slowly than HA proteins and thus could be a good target for an influenza vaccine that provides long-term protection.

In the new study, the researchers (supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health) took antibody-producing cells from the blood of a volunteer sick with H3N2 influenza and screened for monoclonal antibodies (mAbs). The mAbs the researchers found were tested in the laboratory for their ability to bind to different kinds of influenza proteins.

Of 45 mAbs tested, three bound to NA proteins of an H3N2 influenza virus strain. These three mAbs also bound to NA proteins from multiple other types of influenza viruses.

The researchers then treated mice with the mAbs and infected them with different types of influenza viruses. The mAbs inhibited many kinds of NA proteins from different types of influenza viruses and protected most of the mice from severe influenza infections. Mice given lethal doses of H3N2 influenza virus survived when treated with low doses of the three antibodies.

If additional testing supports these early results, the researchers suggest that these potent mAbs could become the basis for a new antiviral treatment. Additionally, the antibodies could inform the development of new influenza vaccines designed to induce similar antibodies that could provide more effective and longer-lasting immunity than current HA-based influenza.

The study was published in Science.