Breathe in deeply against Covid-19: Synthetic nanobodies prevent infection

Thursday, August 13, 2020

By Klaus Wedekind

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US scientists are developing synthetic antibodies that can render the coronavirus harmless. Taken by inhaler or nasal spray, “AeroNabs” are supposed to prevent infection for a day in an uncomplicated and inexpensive way.

If the final tests are successful, “AeroNabs” could play an important role in the fight against the corona pandemic. These are artificial antibodies that scientists at the University of California in San Francisco have developed.

In a Preliminary study In experiments with living viruses, the researchers found that their synthetic molecules can effectively prevent Sars-Cov-2 from docking on human cells. To protect yourself against infection, it should be sufficient to ingest the active ingredient once a day via a nasal spray or an inhaler. The costs should also be so low that nothing speaks against mass use.

Inspired by llamas

For their “AeroNabs”, the scientists were inspired by special antibodies that llamas, camels and related animals have in their blood. They were discovered back in the 1980s, are smaller and more simply structured than human antibodies and are therefore more flexible. As the “Pharmaceutical Newspaper“reported that in 2002/03 Belgian and Texan scientists injected llamas with spike proteins from the Sars virus, which was rampant at the time, and proteins from Mers virus. The animals developed small antibodies against both pathogens. In May, they tested the effectiveness of these antibodies against Sars -Cov-2 and discovered that they also neutralized the new coronavirus.

The California scientists’ nanobodies showed in the laboratory that their synthetic antibodies, like those of the llamas, can prevent Sars-Cov-2 spike proteins from docking on human cells. But they work even better: They do not first block active proteins, but are already effective before their so-called receptor binding domain (RBD) search for suitable receptors on host cells.

Extremely effective and stable

Because a spike protein has three RBDs, the scientists have developed molecular chains with three different antibodies for their active ingredient. In experiments it was found that this combination is 200,000 times more effective than a single antibody against Sars-Cov-2. Through further improvement, they would have achieved an effectiveness that exceeded the possibilities of measurability, says an author of the study.

Finally, the researchers carried out stress tests with the “AeroNabs”, exposed them to high temperatures and turned them into a storable powder and an aerosol. It turned out that the processes that normally cause considerable damage to proteins cannot harm the nanobodies. They have lost none of their antiviral effects, it says in the Press release der University of California.

The researchers now hope to begin human studies as soon as possible. One of the scientists says that they are already in talks with interested commercial partners. “If the ‘AeroNabs’ prove to be as effective as we expect, they could help change the course of the pandemic around the world.”

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