inspired by a unique type of antibody-fighting infection found in llamas, alpacas, and other camelids, a research team at the University of California, San Francisco, has synthesized a molecule that they say is one of the most powerful anti-coronavirus- compounds that have been tested in a laboratory to date.
Named nanobodies, because they are about a quarter of the size of antibodies found in humans and most other animals, these molecules can nest in the nooks and crannies of proteins to block viruses from attaching and infecting cells.
The lab-made one made by the UCSF team is so stable that it can be converted to a dry powder and aerosolized, which means it would be much easier to manage than Covid-19 treatments being developed with human monoclonal antibodies. While the work is still very preliminary, the goal is to deliver the synthetic nanobody through simple inhalation injections to the nose or lungs, allowing it to potentially self-manage and prophylactically against Covid-19 – if it is safe and effective in both shown animal tests and clinical trials.
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After four months of working almost around the clock, the team posted the results on the bioRxiv preprint server on Monday. The paper has not yet been peer-reviewed, but researchers said they are already in talks to find a partner who can quickly test, produce and distribute the new compound in hopes that it can prevent new infections and reduce disease in those who are already infected. “Every day 5,000 people die from this disease. We want to find a partner to do this as quickly and as quickly as possible, “said Peter Walter, a veteran biochemist who permanently lives on many short lists of those expected to win a Nobel Prize and who runs the project. co-led structural biologist Aashish Manglik.
Aware of the furor about early announcements for coronavirus therapies, the duo does not want to bribe their findings and recognize that the nanobody, called Aeronab 6, needs to be tested in clinical studies. But they are enthusiastic about both how stable the compound is and how well it has responded in lab tests where it prevents cell infection by being cruelly linked to the infamous spike proteins that enter coronavirus particles and cells. infect. “It’s almost like a mousetrap that never lets go,” Walter said.
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While the laboratory results look promising, experts in the field advise caution, as important work has not been done to test the composition in animals. ‘The critical thing is data on animals. We have found things in vitro that are very potent that do nothing in vivo, “said Dimiter Stanchev Dimitrov, a professor of medicine who directs the Center for Antibody Therapeutics at the University of Pittsburgh and is anti-anti. therapeutic has made for numerous viruses, including SARS and MERS, two other coronaviruses. He said it can take months to collect the necessary data in animals. “Once these are tested in animal models, I can be excited. “
Dimitrov said that although administering an antibody therapy via an inhaler was an exciting idea that other groups were also investigating, there could be difficulties in delivering a drug uniform into the lungs. “It’s difficult to deliver antibodies to the lung,” he said.
The power of the nanobody against coronavirus was tested at the Institut Pasteur in Paris by Veronica Rezelj, a postdoctoral researcher in the viral populations and pathogens of the institute. When Rezelj mixed coronavirus and small amounts of the nanobody on cell plates, the Vero-E6 cells (derived from the kidney cells of African green monkeys and often used in lab work) were protected against infection and survived.
“Within four days of the day the package arrived from the US, we knew we had a very potent nanobody,” she said. “Very little nanobody was needed to completely eliminate virus infectivity.” She said the effectiveness of the nanobody was much higher than in published data on neutralizing antibodies taken from the blood of Covid-19 patients, than other synthetically made nanobodies.
Rezelj has been testing many antivirals against the coronavirus in recent months; many will not even work in cell culture as animal models, let alone humans. The nanobodies, she said, were more promising: “We are very confident that they could work from a therapeutic point of view after human clinical trials have been completed.”
Thousands of related therapies using human monoclonal antibodies are being developed for use against the coronavirus, with some already in clinical trials, but Walter and Manglik are skeptical about how widespread and practical this approach will be: They are expensive to produce in mammalian cells , should be administered intravenously by medical personnel, and require high doses, as they travel through the bloodstream before reaching the lungs. The UCSF researchers think that an effective approach could be to target nasal passages, where the virus can be detected first before it is seeded in the lungs.
Their compound, they say, could be made cheaply in enormous quantities using bacteria such as yeast, and would require low doses because it is so potent against the virus and can be administered directly to the lungs and as nasal passages. “We want this to be made available to developing countries,” Walter said. “This is possible because it can be shipped as a dry powder and it would have to be very cheap to produce.”
Other labs around the world, including the University of Oxford and the Rosalind Franklin Institute, have recently published work on synthetic nanobodies. In May, a University of Texas group showed true llama antibodies constructed in the lab helped prevent coronavirus infection in laboratory studies. And this week, a team from China in bioRxiv reported that the camel was actively producing nanobodies against the Covid-19 virus. Some of those researchers said they preferred to wait for comment on the new work until after it was published in a journal and peer-reviewed.
Team members, who normally work on research such as deciphering the shape of receptors on cell membranes and understanding how proteins work out, jumped at the chance to work on coronavirus therapies in March. “When UCSF shut down all research operations except coronavirus work, we stopped our regular work and really pivoted,” Manglik said.
The project took advantage of a massive library of synthetic nanobodies produced in yeast that Manglik helped create a few years ago, long before the pandemic, to better understand the structure of proteins to aid in drug design and further basic research. “The library would not have been there without the urge for basic research,” Walter said.
It took Walter and his student Michael Schoof to press Manglik to use the library to hunt down a weapon against the coronavirus. Manglik, who is also an MD, had recently started his lab at UCSF and said he saw the tools he developed to engineer and optimize proteins for basic research as uniquely positioned “to address the pandemic death toll directly” . “
They screened the library’s collection of 2 billion nanobodies quickly for those who might be working against the Covid-19 coronavirus using its spike protein to fish up nanobodies attached to it. She then killed that group after about 20 nanobodies that worked especially well to prevent the virus from entering and infecting cells. Aeronab 6 came to the top because it bound to the spike protein in a really strong and unique way and because it was so stable. Walter, Manglik, and Schoof hold a patent on the connection.
Even though the nanobody worked well from the beginning, Manglik led an attempt to optimize the molecule so that it would be even more effective. The team created a version that both prevented the coronavirus from binding spike proteins to the cell and locking the spikes down so that they remained in a position that made them unavailable for binding. They also “humanized” the nanobody so that it closely resembles a human protein and thus would be less likely to produce an allergic than immune response.
Manglik is not a fan of working with true llamas; There are the objections and veterinary bills, not to mention that it takes months for an animal to produce nanobodies after being infected with a pathogen. But he gives the animals credit: “We are faced with the challenge of building molecules that are as beautiful as those produced in nature and we take deep inspiration from the kind of antibodies that exist in camels, alpacas and llamas. “
He said the work was only possible because of the drive of the many trainees on the project, some of them working regularly until 3 or 4 in the morning. The trainees, Manglik said, lacked experience, but made it out in enthusiasm and by “working to the limits of their physical capacity.”
Those trainees say they were inspired by Manglik’s willingness to work endless hours in the lab doing routine banking, even pipetting during Zoom meetings. “Here’s a full-fledged professor who comes, gloves up and purifies proteins,” Schoof said.
UCSF scientists see Aeronab 6 as something that could be offered to people who have recently tested positive for coronavirus to prevent disease progression. It could also be offered to people who are exposed to the disease to prevent infection, or used as a daily prophylaxis for those at high risk for infection, such as health care workers, first responders, and prison guards.
