Recently, a research team from Tsinghua University isolated a set of nano-antibodies from immunized alpacas.
They found that it has broad-spectrum and highly efficient neutralizing activity against a variety of new coronavirus variants (such as BF.7, BQ.1.1 and XBB) that are currently emerging in China and abroad, as well as SARS virus.
Currently, the continuous emergence of new coronavirus variants has led to the reduction or disappearance of the activity of existing vaccines and neutralizing antibody drugs.
This makes higher demands on the development of next-generation antibody drugs.
The recently discovered nanobodies may be ideal candidates for a new generation of nanobody drugs.
The related study was published in Nature Communications.
The researchers used the neocoronavirus stinger protein (S protein), and a chimpanzee adenovirus vector vaccine carrying the S protein to immunize the alpacas.
Next, 593 nano-antibodies that bind to recombinant stinger protein trimers of the prototype strain of neocoronavirus were isolated from alpacas that developed an immune response by yeast demonstration techniques.
There were 124 pseudoviruses with neutralizing ability against the prototype strain of the new coronavirus.
Ninety-one of these antibodies are also cross-neutralizing to SARS virus viruses, and all except two can bind strongly to the receptor binding domain (RBD) in the S protein.
They also resolved the high-resolution crystal structure of the antibody bound to RBD to reveal its molecular structure and antiviral mechanism.
By injecting a transgenic mouse with the discovered 3-2A2-4 nanobody, they confirmed that this nanobody is effective in preventing infection with Omicron and Delta live viruses.
This nanoantibody exhibits excellent protective capabilities, such as preventing and reducing lung tissue infections.