As the COVID-19 pandemic continues to impact the world, various treatment options continue to be explored. Researchers from China have identified nanobodies (Nb) derived from immunized camels that have the potential to treat and prevent the acute respiratory issues associated with COVID-19.
In order to attack the body, SARS-CoV-2 relies on its spike glycoprotein homotrimer. Its receptor-binding domain (RBD) binds to the hosts angiotensin converting enzyme 2 (ACE2). Nbs are single variable domain (VHH) and resemble traditional antibodies. Their small size and high stability make them easy to nebulize and may prove valuable in the treatment of the coronavirus.
Through Nbs, researchers created a phage display library using the SARS-CoV-2 strain offered by the National VirusResource, Wuhan Institute of Virology, Chinese Academy of Science. They found that Nb11-59 is a prophylactic and therapeutic molecule that can fight SARS-CoV-2 through inhalation treatment. The researchers were in search of Nbs capable of binding to SARS-CoV-2. They found that 229 out of 381 Nbs bind to the 8 mutants. The remaining 152 also bound to at least one mutant.
As the virus continues mutating, researchers are seeking preparation for future outbreaks. Drugs that present broad spectrum neutralizing activity are currently being developed. Researchers are analyzing the neutralizing capabilities of the 7 Nbs that are related to different strains.
Researchers have identified Nb11-59 as the best neutralizer for SARS-CoV-2 with a 50% neutralizing dose of 0.55 μg/ml. This Nb has been humanized and expressed in a yeast through fermentation. The production resulted in 20 g/L titers and 99.36% purity. This means it may be widely used as a treatment option.
Continued study of these 7 Nbs could allow researchers to develop new therapeutic and diagnostic tools for the coronavirus. This small in size, single domain antibody is presenting a high stability treatment option. Through inhalation, the neutralizing Nb could help prevent and treat current and future patients suffering from the coronavirus.