Llama antibodies could tackle COVID-19 virus infection: Study

July 20, 2020 0 By FM

Antibodies derived from llamas have been shown to neutralise the SARS-CoV-2 virus in lab tests, according to a new study published in Nature Structural & Molecular Biology.
 

Llamas naturally produced quantities of small antibodies with a simpler structure, that can be turned into nanobodies. The researchers from Rosalind Franklin Institute, Oxford University, and Diamond Light Source and Public Health England engineered the newly developed nanobodies using a collection of antibodies taken from llama blood cells. They have shown 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 to other antibodies already discovered.

“The electron microscopy structures showed us that the three nanobodies can bind to the virus spike, essentially covering up the portions that the virus uses to enter human cells,” said Professor David Stuart, from Diamond Light Source and Oxford University.

Transfusion of critically ill patients with serum from recovered individuals, which contain human antibodies against the virus, has been shown to greatly improve the clinical outcome of COVID-19. This, in turn, creates a passive immunisation in the body against the infectious organism. But to identify the right individuals with the right antibodies and to give such a blood product safely calls for a risk. A lab-based product that can be made on-demand would have considerable advantages and could be used earlier in the disease where it is likely to be more effective say the researchers.

“These nanobodies have the potential to be used in a similar way to convalescent serum, effectively stopping the progression of the virus in patients who are ill. 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.” explained Professor James Naismith, Director of The Rosalind Franklin Institute and Professor of Structural Biology at Oxford University.

The team started from a lab-based library of llama antibodies. They are now screening antibodies from the llama based at the University of Reading, taken after immunisation with harmless purified virus proteins.

The team is investigating preliminary results which show that llama’s immune system has produced different antibodies from those already identified, which will enable cocktails of nanobodies to be tested against the virus.