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Scientists have isolated a set of tiny antibodies or nanobodies that show promise against the novel coronavirus from a llama, some of which may help prevent infection.
Preliminary results, published in the journal Scientific Reports, suggest that the nanobody appears to work in both liquid and aerosol form, suggesting that it may remain effective after inhalation.
Researchers at the National Institutes of Health (NIH) in the United States have said that at least one of these nanobodies, called NIH-CoVnb-112, could prevent infections and detect viral particles by grabbing spike proteins from SARS- CoV-2, which causes COVID-19.
“We hope that these anti-COVID-19 nanobodies can be very effective and versatile in the fight against the coronavirus pandemic,” said David L. Brody, who is also a professor at the Uniformed Services University for the Health Sciences.
A nanobody is a special type of antibody naturally produced by the immune system of camels, a group of animals that includes camels, llamas, and alpacas.
On average, these proteins are about a tenth the weight of most human antibodies, the researchers said.
Indeed, the nanobodies isolated in the lab are essentially floating versions of the ends of the arms of heavy chain proteins, which form the backbone of a typical Y-shaped human IgG antibody, they said.
These tips play a vital 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, cheaper to produce, and easier to design than conventional antibodies, a growing number of researchers are 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 in preventing infections.
In the latest study, the researchers used a slightly different strategy than others to find nanobodies that can perform particularly well.
“The SARS-CoV-2 spike protein acts as a key. It does this by opening the door to infections when it binds to a protein called angiotensin-converting enzyme receptor 2 (ACE2), found on the surface of some cells, ”said Thomas J. Esparza, lead author of the study.
“We have developed a method that would isolate nanobodies that block infections by coating the teeth with the spike protein that bind to and unblock the ACE2 receptor,” said Esparza.
Researchers immunized a llama called Cormac five times in 28 days with a purified version of the SARS-CoV-2 spike protein.
After testing hundreds of nanobodies, they discovered that Cormac produced 13 nanobodies that could be good candidates.
Early experiments suggested that a candidate, called NIH-CoVnb-112, might work very well, the researchers said.
Test tube studies have shown that this nanobody binds to the ACE2 receptor 2 to 10 times stronger than nanobodies produced by other labs, they said.
Further experiments suggested that the NIH nanobody sticks directly to the ACE2 receptor binding portion of the spike protein.
The team then showed that the NIH-CoVnB-112 nanobody could be effective in preventing coronavirus infections.
To mimic the SARS-CoV-2 virus, the researchers genetically mutated a harmless “pseudovirus” so that it could use the spike protein to infect cells that have human ACE2 receptors.
The researchers found that relatively low levels of the NIH-CoVnb-112 nanobodies prevented the pseudovirus from infecting these cells in Petri dishes.
They showed that the nanobody was just as effective at preventing infections in Petri dishes when sprayed through the type of nebulizer, or inhaler, often used to help treat patients with asthma.
(Disclaimer: This story was not edited by www.republicworld.com and is auto-generated from a syndicated feed.)
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