| Date | 28th, Dec 2020 |
|---|
Ever since the beginning of the pandemic, researchers working on treatments for COVID-19 have been studying nanobodies – a special type of antibody produced by the immune systems of camels, llamas, and other camelids – as they are more stable, easier to produce, and less expensive than typical antibodies.
While there are already several candidate nanobodies that have shown promise against the SARS-CoV-2 spike proteins, neuroscientists Thomas J. Esparza, David L. Brody and colleagues from NIH’s National Institute of Neurological Disorders and Stroke (NINDS) used a different strategy to identify even more potent nanobodies.
Llamas and other camelids could be an unexpected source of nanobodies effective at preventing COVID-19. Image: Deensel via flickr.com, CC BY 2.0
“The SARS-CoV-2 spike protein acts like a key. It does this by opening the door to infections when it binds to a protein called the angiotensin converting enzyme 2 (ACE2) receptor, found on the surface of some cells,” said Esparza. “We developed a method that would isolate nanobodies that block infections by covering the teeth of the spike protein that bind to and unlock the ACE2 receptor.”
As described in a study published in the journal Scientific Reports, the researchers immunised a llama (named Cormac) five times over a period of 28 days with a purified version of the SARS-CoV-2 spike protein and tested the massive number of nanobodies produced in response to the immunisation.
Out of the 13 promising candidates, one called NIH-CoVnb-112 was shown to bind to the ACE2 receptor 2 to 10 times stronger than nanobodies discovered by other research teams.
To test its effectiveness against SARS-CoV-2, Esparza and Brody genetically engineered a harmless pseudovirus, enabling it to use the spike protein to infect cells with human ACE2 receptors. Results showed that even at low amounts, the nanobody was effective at preventing infection in petri dishes.
The nanobody was also found to be effective in both liquid and an aerosol form, which means that it could be inhaled to coat the airways and lungs.
Esparza and Brody are continuing their work on the nanobody with the NIH to expedite further testing, and have already applied for a patent.
Source: ninds.nih.gov
