In a new study, researchers have isolated a set of promising, tiny antibodies, or “nanobodies,” against COVID-19 that were produced by a llama named Cormac.
They found that at least one of these nanobodies, called NIH-CoVnb-112, could prevent infections and detect virus particles by grabbing hold of SARS-CoV-2 spike proteins.
In addition, the nanobody appeared to work equally well in either liquid or aerosol form, suggesting it could remain effective after inhalation.
The research was conducted by the National Institutes of Health scientists.
A nanobody is a special type of antibody naturally produced by the immune systems of camelids, a group of animals that includes camels, llamas, and alpacas.
On average, these proteins are about a tenth the weight of most human antibodies.
This is because nanobodies isolated in the lab are essentially free-floating versions of the tips of the arms of heavy chain proteins, which form the backbone of a typical Y-shaped human IgG antibody.
These tips play a critical role in the immune system’s defenses by recognizing proteins on viruses, bacteria, and other invaders, also known as antigens.
Because nanobodies are more stable, less expensive to produce, and easier to engineer than typical antibodies, a growing body of researchers, have been using them for medical research.
Since the pandemic broke, several researchers have produced llama nanobodies against the SARS-CoV-2 spike protein that may be effective at preventing infections.
In the current study, the researchers used a slightly different strategy than others to find nanobodies that may work especially well.
Initial experiments suggested that one candidate, called NIH-CoVnb-112, could work very well.
Test tube studies showed that this nanobody bound to the ACE2 receptor 2 to 10 times stronger than nanobodies produced by other labs.
Other experiments suggested that the NIH nanobody stuck directly to the ACE2 receptor binding portion of the spike protein.
Then the team showed that the NIH-CoVnB-112 nanobody could be effective at preventing coronavirus infections.
Importantly, the researchers showed that the nanobody was equally effective in preventing the infections in petri dishes when it was sprayed through the kind of nebulizer, or inhaler, often used to help treat patients with asthma.
The team has applied for a patent on the NIH-CoVnB-112 nanobody.
The team says with support from the NIH we are quickly moving forward to test whether these nanobodies could be safe and effective preventative treatments for COVID-19.
One author of the study is David L. Brody, M.D., Ph.D.
The study is published in Scientific Reports.
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