An international research team led by the University of Bonn has identified and further developed novel antibody fragments against SARS-CoV-2, the virus that causes Covid-19. These “nanobodies” are much smaller than classic antibodies (which were used to treat United States President Donald Trump, for example) — and they, therefore, penetrate the tissue better and can be produced more easily in larger quantities, the university said in a media release.
The researchers at University Hospital Bonn have also combined the nanobodies into potentially particularly effective molecules, which attack different parts of the virus simultaneously.
The new approach could prevent the pathogen from evading the active agent through mutations, the university said. The results have been published in the journal Science. (‘Structure-guided multivalent nanobodies block SARS-CoV-2 infection and suppress mutational escape’; Paul-Albert Köenig et. al)
Antibodies are an important weapon in the immune system’s defense against infections. They bind to the surface structures of bacteria or viruses and prevent their replication. One strategy in the fight against disease is therefore to produce effective antibodies in large quantities and inject them into patients. However, producing antibodies is difficult and time-consuming; they are, therefore, probably not suitable for widespread use.
The researchers instead focussed on another group of molecules, the nanobodies. “Nanobodies are antibody fragments that are so simple that they can be produced by bacteria or yeast, which is less expensive,” the university quoted study co-author Dr Florian Schmidt as saying.
“We first injected a surface protein of the coronavirus into an alpaca and a llama,” Dr Schmidt said. “Their immune system then produces mainly antibodies directed against this virus. In addition to complex normal antibodies, llamas and alpacas also produce a simpler antibody variant that can serve as the basis for nanobodies.”
A few weeks later, the researchers took a blood sample from the animals, from which they extracted the genetic information of produced antibodies. This “library” still contained millions of different construction plans. In a complex process, they extracted those that recognise an important structure on the surface of the coronavirus, the spike protein. “Altogether we obtained dozens of nanobodies, which we then analyzed further,” the media release quoted study co-author Dr Paul-Albert Köenig as saying.
Source: University of Bonn
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