Since the start of the pandemic, scientists have been working to develop antibody treatments for COVID-19. Several of these treatments are now in late-stage clinical trials, with a handful having been approved for emergency use in the US and other countries.
However, due to the need for the treatment to be administered through intravenous infusions rather than directly to the respiratory tract, where the virus is mainly found – it takes high doses for them to be effective. This means that doctors are reluctant to administer them. Another challenge is the emergence of SARS-CoV-2 variants that seem to be resistant to some existing antibodies.
Zhiqiang An, an antibody engineer at the University of Texas Health Science Center at Houston set out to engineer an antibody treatment that could be administered as a nasal spray, thereby targeting the respiratory tract more effectively.
Together with his team he scanned a library of antibodies from healthy humans and zeroed in on those that were able to recognize a component of SARS-CoV-2 that the virus uses to latch on to and enter cells.
They then stitched the promising antibodies to a different type of molecule, IgM antibodies, which act as first-responders to a broad range of infections.
These engineered IgMs had a much stronger "neutralizing" effect against over 20 different variants of COVID-19 than they would have had otherwise.
When the antibody treatment was sprayed into the noses of mice during trials, either six hours before infection or six hours after infection, the viral level of their lungs was significantly reduced within two days, the team found.
Scientists hope that these antibodies, should they prove to be effective in human trials, will serve as an extra line of defense for people who are not fully protected by the vaccine.