Antibodies Derived from Llamas Neutralize SARS-CoV-2 Virus

Antibodies derived from llamas have been shown to neutralize the SARS-CoV-2 virus in lab tests, raising hopes that they could eventually be developed as a treatment for patients with severe COVID-19.

Researchers from the University of Oxford (Oxford, UK) in collaboration with the Rosalind Franklin Institute, Oxford University, Diamond Light Source and Public Health England engineered their new antibodies, known as nanobodies due to their small size, using a collection of antibodies taken from llama blood cells. Llamas, camels and alpacas naturally produce quantities of small antibodies with a simpler structure that can be turned into nanobodies. The researchers have demonstrated that the nanobodies bind tightly to the spike protein of the SARS-CoV-2 virus, blocking it from entering human cells and stopping infection. Using advanced imaging with X-rays and electrons, the team also identified that the nanobodies bind to the spike protein in a new and different way than the other antibodies that have been already discovered.

The team started from a lab-based library of llama antibodies and is now screening antibodies from Fifi, one of the ‘Franklin llamas’ based at the University of Reading, taken after she was immunized with harmless purified virus proteins. The researchers are investigating preliminary results which show that Fifi’s immune system has produced different antibodies from those already identified, which will enable cocktails of nanobodies to be tested against the virus.

“These nanobodies have the potential to be used in a similar way to convalescent serum, effectively stopping progression of the virus in patients who are ill,” said Professor James Naismith, Director of The Rosalind Franklin Institute and Professor of Structural Biology at Oxford University. “We were able to combine one of the nanobodies with a human antibody and show the combination was even more powerful than either alone. Combinations are particularly useful since the virus has to change multiple things at the same time to escape; this is very hard for the virus to do. The nanobodies also have potential as a powerful diagnostic.”

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