National Institute of Health researchers have isolated a set o promising, tiny antibodies or nanobodies against SARS-CoV-2 produced by a llama. Preliminary results suggest 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.
The nanobody appeared to work equally well in either liquid or aerosol form, suggesting it could remain effective after inhalation. A nanobody is a special type of antibody naturally produced by the immune systems of camelids. These are about a tenth the weight of most human antibodies. his is because nanobodies isolated in the lab are essentially free-floating versions of the tips of the arms of heavy chain proteins. 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. To isolate the nanobodies, researchers immunized the llama five times over 28 days with a purified version of the SARS-CoV-2 spike protein.
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. The researchers saw that relatively low levels of the NIH-CoVnb-112 nanobodies prevented the pseudovirus from infecting these cells in Petri dishes.
Ref link: https://www.nature.com/articles/s41598-020-79036-0