Research: fight flu viruses more effectively

Discovered new points of attack against flu viruses?

The limited effectiveness of the flu vaccine used and the lack of options for drug treatments became evident in the course of this year's flu season. Hundreds of thousands fell ill and many people succumbed to the consequences of the infection. Scientists from the University of Zurich (UZH) have now discovered a new mechanism that could possibly also be used to develop better flu vaccines and more effective medicines.

In cooperation with American scientists, the UZH research team has discovered a new mechanism by which antibodies in the lungs interact with flu viruses. The hitherto unknown type of binding opens up new opportunities to develop better vaccines and effective medicines for flu, according to the UZH. The researchers published their results in the "Cell Reports" magazine.

Millions of flu infections every year?

According to the researchers, millions of people worldwide suffer from flu every year, with most of those affected recovering after a few days. But according to WHO estimates, 250,000 to 500,000 deaths from an influenza infection are also reported annually. Since there are hardly any effective treatments, the medicine has so far focused on the flu shot. However, these uncertainties also hide, since influenza viruses and thus also the virus strains that circulate worldwide change continuously. “The vaccines therefore have to be manufactured every year based on forecasts,” the experts explain.

What types of antibodies are most effective?

In search of new ways to combat the flu virus, the scientists tested in cell cultures which types of antibodies work best against the flu virus. The antibodies of the IgA1 subtype were found to be the most effective. "Antibodies of the IgA type, which are often found on the surface of mucous membranes, can protect us from infections in two different ways," explains Lars Hangartner, former professor at the Institute for Medical Virology at UZH and head of the study.

Antibodies of the IgA1 subtype particularly effective?

The experts explain that flu vaccines work by presenting antigens to the immune system. Thanks to this, the immune system can learn to recognize influenza viruses and produce antibodies against them as soon as these viruses are recognized. However, today's flu vaccines stimulate the formation of other types of antibodies - namely immunoglobulins G (IgG). In the tests of different types in cell cultures, however, the antibodies of the IgA1 subtype, which have a special tip with sialic acids at one end of the molecule, have proven to be the most effective.

Two mechanisms of antibodies?

The special tip of these antibodies block that part of the flu virus "that allows it to bind to the cells and infect them," reports the UZH. This indicates that IgA1 antibodies have two types of immune activity - on the one hand the acquired immunity, thanks to which the antibodies with their classic binding sites specifically recognize the pathogens, and on the other hand the innate immunity via the sialic acids at the other end of the molecule, with which the viruses rather unspecific and widely attacked.

Develop new antibodies?

According to the researchers, the IgA antibodies attach themselves to two sites of the flu virus at the same time. According to the study leader, the findings should help to improve the effects of flu vaccines and drugs in the future. However, antibodies of the IgA type are difficult to handle, which is why new antibodies have to be developed that are easier to produce and test on mice, according to Hangartner. The researchers are therefore pursuing the idea of ​​grafting the tip of the IgA1 onto an IgG-type antibody, which is much easier to handle. "This would combine the advantages of both types of antibodies," emphasizes the expert. Such a molecule would be more effective and resistant and should be very useful for fighting the flu, emphasizes the study leader. Thanks to the strong binding of the antibodies to the viruses, even small amounts would be sufficient to provide effective protection, the expert continues. (fp)

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