Llama nanobodies could be a powerful new weapon against COVID-19.

Researchers at the University of Pittsburgh School of Medicine describe a new method in the journal Science for extracting tiny but extremely potent SARS-CoV-2 antibody fragments from lamas, which are turned into inhalable therapies with the potential to prevent and treat COVID-19 could .

These special llama antibodies, called “nanobodies”, are much smaller than human antibodies and many times more effective in neutralizing the SARS-CoV-2 virus. They are also much more stable.

“Nature is our greatest inventor,” said senior author Dr. Yi Shi, assistant professor of cell biology at Pitt. “The technology we have developed studies SARS-CoV-2 in the neutralization of nanobodies on an unprecedented scale, enabling us to rapidly discover thousands of nanobodies with unmatched affinity and specificity.

To create these nanobodies, Shi turned to a black llama named Wally, who resembles Shi’s black Labrador and therefore shares his nickname with him.

Dr. Yi Shi, senior author of an article published in Science, explains how “nanobodies” could be a powerful new weapon against the COVID-19 pandemic. Credit: UPMC

Shi and colleagues immunized the llama with a piece of the SARS-CoV-2 spike protein, and after about two months the animal’s immune system was producing mature nanobodies against the virus.

Using a mass spectrometry-based technique that Shi has perfected over the past three years, lead author Yufei Xiang, a research assistant in Schi’s lab, has identified the nanobodies in Wally’s blood that bind most strongly to SARS-CoV. -2.

Then, with the help of Pitt’s Center for Vaccine Research (CVR), the scientists exposed their nanobodies to live SARS-CoV-2 virus and found that only a fraction of nanograms could neutralize enough viruses to prevent one million from cells to be infected. preserves.

These nanobodies are among the most potent therapeutic antibodies candidates for SARS-CoV-2 and are hundreds to a thousand times more potent than other llama nanobodies discovered using the same phage display methods that have been used to fish human monoclonal antibodies for decades. .

Schi nanobodies can be stored at room temperature for six weeks and can tolerate the formation of an inhalable mist to deliver antiviral therapy directly to the lungs where it is needed most. Since SARS-CoV-2 is a respiratory virus, nanobodies could find the virus in the airways and settle there before it even has a chance to cause harm.

In contrast, traditional SARS-CoV-2 antibodies require an infusion that dilutes the product throughout the body, which requires a much higher dose and costs patients and insurers around $ 100,000 per course of treatment.

“The nanobodies could potentially cost a lot less,” Shi said. “They are ideal for addressing the urgency and dimensions of the current crisis”.

In collaboration with Dr. Cheng Zhang, Pitt and Dr. Dina Schneidman-Duhovny, Hebrew University of Jerusalem, the team found that their nanobodies use a variety of mechanisms to block SARS-CoV-2 infection. This makes the nanobodies ready for bioengineering. For example, nanobodies that bind to different regions of the SARS-CoV-2 virus can be linked together like a Swiss army knife if part of the virus is mutated and becomes drug resistant.

“As a virologist, it is amazing to see how harnessing the whims of llama antibody generation can result in the creation of a potent nanoparticle against clinical SARS-CoV-2 isolates,” said Dr. Paul Duprex, co-author of the study and director of the CVR.

Reference: “Versatile and Multivalent Nanobodies Effectively Neutralize SARS-CoV-2” by Yufei Xiang, Sham Nambulli, Zhengyun Xiao, Heng Liu, Zhe Sang, W. Paul Duprex, Dina Schneidman-Duhovny, Cheng Zhang and Yi Shi, November 5, 2020 , science.
DOI: 10.1126 / Wissenschaft.abe4747

Other authors of the study include Sham Nambulli, Ph.D., Zhengyun Xiao, Heng Liu, Ph.D., and Zhe Sang, all of Pitt.

Funding for this study was provided by the National Institutes of Health (Grants R35GM137905 and R35GM128641), the University of Pittsburgh Clinical and Translational Science Institute, the Pitt Center for Vaccine Research, and the DSF Charitable Foundation.