Inhibiting SARS-CoV-2 Virus Using Neutralizing Nanobodies

A recent study conducted by investigators from the Walter and Eliza Hall Institute, in collaboration with the Doherty Institute and the Kirby Institute, have discovered in preclinical models neutralizing nanobodies that are able to block the SARS-CoV-2 virus from entering into cells.

Results from study were published in Proceedings of the National Academy of Sciences.

"By combining the two leading nanobodies into this nanobody cocktail, we were able to test its effectiveness at blocking SARS-CoV-2 from entering cells and reducing viral loads in preclinical models," Wai-Hong Tham, lead author on the study said.

For the study, the investigators immunized a group of alpacas with a synthetic, non-infectious part of the spike protein from the SARS-CoV-2 virus, which allowed the animals to create nanobodies against COVID-19.

"The synthetic spike protein is not infectious and does not cause the alpacas to develop disease - but it allows the alpacas to develop nanobodies," Tham said. "We can then extract the gene sequences encoding the nanobodies and use this to produce millions of types of nanobodies in the laboratory, and then select the ones that best bind to the spike protein."

The team was then able to map the nanobodies and identify which ones were able to recognize the virus, as well as several variants.

They discovered that the identified nanobodies effectively blocked the virus from entering cells.

An additional finding showed that the nanobodies also blocked the original SARS virus, indicating that they may provide cross-protection against future human coronaviruses.

"In the wake of COVID-19, there is a lot of discussion about pandemic preparedness. Nanobodies that are able to bind to other human beta-coronaviruses - including SARS-CoV-2, SARS-CoV and MERS - could prove effective against future coronaviruses as well," Tham said.