September 27 - October 3 2021
A modified antibody that is more effective
Several neutralising antibodies that target SARS-CoV-2 have been developed and are undergoing clinical testing. Two anti-COVID-19 antibody cocktails are already on the market and reduce the risk of hospitalisation by 80%. However, these antibodies need to be administered in high doses, and their effectiveness remains limited. Researchers at the Universities of Rockefeller in New York and North Carolina have developed an optimised antibody that is more effective in preventing or treating SARS-CoV-2 infection.
This involved modifying an anti-SARS-CoV-2 antibody by enhancing its binding with the Fcɣ receptors. The Fcɣ receptors are present on the surface of immune cells and recognise antibodies through their Fc fragment. The antiviral activity of the antibodies is mediated by interaction with these receptors, enabling the effector functions to eliminate viral particles and infected cells, as well as inducing a T lymphocyte response. The scientists first tested this modified antibody on a hamster model having the same clinical signs of COVID-19 as humans, and on a mouse model. What were the results? The modified antibody enabled protection of the infected animal while reducing 5-fold the level of the administered dose. In addition, the administration of a preventative dose before infection protected the animal.
In conclusion, the researchers have developed an antibody by modifying its Fc fragment so as to enable better binding with the Fcg receptors of the immune cells. These modified antibodies are more effective, and can be given in much smaller doses. Even though effective vaccines against COVID-19 are now available, these medicines remain essential, especially for at-risk and immunocompromised people for whom vaccination is ineffective.