Llamas in the fight against the coronavirus: meet winter

Winter is a chocolate-colored four-year-old llama with slender legs, crooked ears and envious eyelashes. Some scientists are hoping she could be an important figure in the fight against the coronavirus.

It is not an overpowered camelid. Winter was simply the lucky llama chosen by researchers in Belgium, where she lives, to participate in a series of viral studies involving both SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). .

Finding that his antibodies prevented these infections, the scientists postulated that these same antibodies could also neutralize the new virus that causes COVID-19. They were right and published their results in the newspaper on Tuesday Cell.

Scientists have long turned to llamas for antibody testing. Over the past decade, for example, they have used the antibodies of llamas in HIV and influenza research, finding promising therapies for both viruses.

Humans produce only one type of antibody, which is made up of two types of protein chains – heavy and light – that together form a Y shape. Heavy chain proteins cover all of Y, while light chain proteins only touch the arms of the Y.

Hello, I am here to fight the virus. Photo: Getty

Llamas, on the other hand, produce two types of antibodies. One of these antibodies is similar in size and construction to human antibodies. But the other is much smaller; it’s only about 25 percent the size of human antibodies. The llama’s antibody still forms a Y, but its arms are much shorter because it lacks light chain proteins.

This smaller antibody can access smaller pockets and crevices on spike proteins – proteins that allow viruses like the coronavirus to enter host cells and infect us – that human antibodies cannot. This can make it more effective at neutralizing viruses.

Llamas’ antibodies are also easily manipulated, said Dr Xavier Saelens, molecular virologist at Ghent University in Belgium and author of the new study. They can be linked or fused with other antibodies, including human antibodies, and remain stable despite these manipulations.

This antibody is a genetic characteristic that llamas share with all camels, the family of mammals that also includes alpacas, guanacos, and dromedaries.

Sharks also have these smaller antibodies, but they “aren’t a great experimental model and are much less cuddly than llamas,” said Daniel Wrapp, a graduate student affiliated with the University of Texas at Austin and Dartmouth College. , and a co-author of the new research.

Dr Saelens said llamas are domesticated, easy to handle and less stubborn than many of their camelid cousins, although “if they don’t like you they will spit”.

In 2016, Dr Saelens, Mr Wrapp, and Dr Jason McLellan, structural virologist at the University of Texas at Austin, and other researchers turned to llamas – and, more specifically, Winter – to find an antibody smaller llama “that could largely neutralize many different types of coronavirus,” said Dr. McLellan.

They injected Winter with advanced proteins from the virus that caused the 2002-03 SARS outbreak as well as MERS, and then tested a sample of his blood. And while they couldn’t isolate a single effective llama antibody against the two viruses, they found two strong antibodies that each fought MERS and SARS separately.

Researchers were writing their findings when the novel coronavirus started making headlines in January. They immediately realized that the smaller llama antibodies “that could neutralize SARS would most likely also recognize the COVID-19 virus,” said Dr Saelens.

The researchers found that it actually inhibited the coronavirus in cell cultures.

The researchers hope the antibody can eventually be used as a prophylactic treatment, injecting a person who is not yet infected to protect them from the virus, such as a healthcare professional.

While treatment protection would be immediate, its effects would not be permanent, lasting only a month or two without additional injections.

This proactive approach is at least several months away, but researchers are heading into clinical trials. Further studies may also be needed to verify the safety of injecting llama antibodies into human patients.

“There is still a lot of work to be done to try to bring this to the clinic,” said Dr Saelens.

“If it works, Llama Winter deserves a statue. “

NYT

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