Ultra-Low Doses of Inhaled Nanobodies Prevents and Treats Severe COVID-19 in Hamsters

Animals that received inhaled nanobodies have fewer coronavirus particles in their bronchioles (right panel, orange) and are less inflamed (magenta). Credit: Nambulli et al., Science Advances

In an article published today (May 26, 2021) in Science Advances, researchers at the University of Pittsburgh School of Medicine showed that inhalable nanobodies targeting the spike protein of the SARS-CoV-2 coronavirus severely affected COVID-19 in hamsters. can prevent and treat. . This is the first time that the nanobodies – which are similar to monoclonal antibodies, but smaller in size, more stable and cheaper to produce – have been tested for inhalation treatment against coronavirus infections in a preclinical model.

The scientists showed that low doses of a nebulized nanobody called Pittsburgh inhalable Nanobody-21 (PiN-21) protected hamsters from the dramatic weight loss typically associated with severe SARS-CoV-2 infection and reduced the number of infectious virus particles in the animals . nasal cavities, throat and lungs millions of times, compared to a placebo treatment with a nanobody that does not neutralize the virus.

“By using an inhalation therapy that can be delivered directly to the site of infection – the airways and lungs – we can make treatments more efficient,” said co-senior author Yi Shi, Ph.D., assistant professor of cell biology at Pitt. . “We are very excited and encouraged by our data suggesting that PiN-21 may be highly protective against serious diseases and potentially prevent human-to-human viral transmission.”

Yi Shi, Ph.D., Assistant Professor of Cell Biology, University of Pittsburgh School of Medicine. Credit: Yi Shi

Previously, Shi and colleagues discovered a large repertoire of more than 8,000 high affinity SARS-CoV-2 nanobodies. From this repertoire, the scientists selected an ultrapotent nanobody (Nb21) and converted it into a trimeric form to further maximize antiviral activity. The resulting PiN-21 is by far the most powerful antiviral nanobody identified, according to the researchers’ review of published studies.

The experiments showed that PiN-21 was protective when administered intranasally at the time of infection. Hamsters in the PiN-21 treatment group did not lose body weight, in contrast to the placebo-treated animals which lost up to 16% of their initial body weight after one week of infection. For the average adult human, the rate of weight loss would correspond to losing about 20 pounds in a week.

More impressively, inhalation of aerosolized nanobodies at an ultra-low dose reduced the number of infectious virus particles in the lung tissue by 6 logs (or a million times). Animals given nebulized PiN-21 nanobodies had milder changes in lung structure and a lower degree of inflammation than those given the placebo.

Doug Reed, Ph.D., Associate Professor of Immunology, University of Pittsburgh School of Medicine. Credit: Doug Reed

To deliver therapeutics via aerosolization, the scientists had to overcome several technical challenges – small particle aerosols must penetrate deep into the lungs and treatment particles must be small enough that they do not clump together and be strong enough to withstand the extreme pressure. needed to hang them in the air. PiN-21 nanobodies, which are approximately four times smaller than typical monoclonal antibodies with exceptionally high stability, are perfectly suited to the task. They are also much cheaper to manufacture and can be generated quickly to adapt quickly to the shape-shifting virus.

“COVID-19 is now a leading disease of the 21st century,” said study co-author Doug Reed, Ph.D., associate professor of immunology at Pitt. “Giving the treatment directly into the lungs can make a big difference to our ability to treat it.”

Researchers point out that the nanobodies and vaccines are complementary and do not compete with each other. Vaccines remain the best tool for preventing the virus from spreading from person to person, but nanobodies will be useful in treating people who are already sick and those who cannot be vaccinated for other medical reasons.

Promising early preclinical data, combined with the researchers’ extensive knowledge of rapidly identifying drug-grade nanobodies, suggests that this approach may provide an easy and cost-effective therapeutic option to manage the coronavirus pandemic.

“This work is the result of a close collaboration between experts in nanobody manufacturing, infectious diseases and aerobiology. At the University of Pittsburgh Center for Vaccine Research, we don’t just talk about ideas, we actually make them come to life, ”said co-senior author Paul Duprex, Ph.D., the center’s director.

Reference: May 24, 2021, Science Advances.
DOI: 10.1126 / sciadv.abh0319

Other authors of the manuscript include Sham Nambulli, Ph.D., Natasha Tilston-Lunel, Ph.D., Linda J. Rennick, Ph.D., William Klimstra, Ph.D., the entire Pitt Center for Vaccine Research; Yufei Xiang, MS, of Pitt’s Department of Cell Biology; Zhe Sang, MS, from Pittsburgh-Carnegie Mellon University Program in Computational Biology; and Nicholas Crossland, Ph.D., from Boston University.

This work was supported by the National Institutes of Health (grant # 1R35GM137905-01), a pilot grant from the University of Pittsburgh Clinical and Translational Science Institute, the University of Pittsburgh, the Pitt Center for Vaccine Research, the Commonwealth of Pennsylvania Department of Community and Economic Development, the Richard King Mellon Foundation and the Henry L. Hillman Foundation.

Shi and Xiang are inventors of a patent pending work, filed by the University of Pittsburgh (No. 63067567, filed August 28, 2020).