A llama named Winter is part of a team fighting to find a treatment for COVID-19, the disease caused by the novel coronavirus.
Antibodies made by llamas might help against the disease, according to research by an international team of scientists. Antibodies are proteins made by the body to fight off infections.
The team created a new antibody that binds tightly to a key "spike" protein on SARS-CoV-2, the virus that causes COVID-19. Coronaviruses are covered with distinctive protein spikes that allow the virus to easily latch into host cells. In initial lab tests, researchers found that the newly created antibody blocked the virus from infecting cells in a culture.
Researchers from The University of Texas at Austin, the National Institutes of Health, and Ghent University in Belgium report their findings in a peer-reviewed study available as a pre-proof in the journal Cell.
"This is one of the first antibodies known to neutralize SARS-CoV-2," Jason McLellan, associate professor of molecular biosciences at UT Austin and co-senior author, said in a statement.
The power of llamas
The new antibody was inspired by 4-year-old Winter, a llama living in Belgium.
Llamas and other camelids such as alpacas are helpful in studies like this because they make two types of antibodies: some that are similar to humans and others that are only about a quarter of the size. These tiny nanobodies or single-domain antibodies are useful as respiratory treatments because they can be nebulized and used in an inhaler. Scientists have created a nasal spray with llama antibodies, for example, hoping they can one day be used for a universal flu vaccine.
This time around, Winter's contribution began four years ago when she was only about 9 months old. In 2016, researchers were studying two earlier coronaviruses: SARS-CoV-1 and MERS-CoV. Just like people get shots to immunize them against a virus, Winter was injected with stabilized spike proteins from those viruses over a period of six weeks. Researchers collected a blood sample and were able to isolate an antibody that showed promise in stopping SARS-CoV-1 from infecting cells in a culture. They called it VHH-72.
"That was exciting to me because I'd been working on this for years," said Daniel Wrapp, a graduate student in McLellan's lab and co-first author of the paper. "But there wasn't a big need for a coronavirus treatment then. This was just basic research. Now, this can potentially have some translational implications, too."
After the COVID-19 outbreak, the team wondered whether the antibody VHH-72 could also be effective against the related SARS-CoV-2. In initial tests, they discovered that it did bind to the spikes in the protein, albeit weakly. To make it bind more effectively, they linked two copies of the antibodies. According to the researchers, the newly engineered antibody is the first that neutralizes both SARS-CoV-1 and SARS-CoV-2.
Next up, the researchers will conduct tests on animals with the hopes of testing on humans next. The goal is to develop a treatment that would help people soon after infection with the novel coronavirus.
"With antibody therapies, you're directly giving somebody the protective antibodies and so, immediately after treatment, they should be protected," McClellan said. "The antibodies could also be used to treat somebody who is already sick to lessen the severity of the disease."