Antibodies with bite: sharks could give ‘insurance’ against Covid
Researchers believe tiny proteins derived from the ocean predators’ immune systems can halt the coronavirus
The answer to preventing coronaviruses in the future may lie with the antibodies of sharks.
Tiny antibody-like proteins known as variable antigen receptors (VNARs) — derived from the immune systems of sharks — can prevent the virus that causes Covid-19, its variants and related coronaviruses from infecting human cells, according to a new study published in Nature Communications.
The study was conducted by researchers from the University of Wisconsin-Madison in the US.
According to the researchers the new VNARs will not be immediately available as a treatment in people, but they can help prepare for future coronavirus outbreaks.
The shark VNARs were able to neutralise WIV1-CoV, a coronavirus that is capable of infecting human cells but circulates only in bats, where SARS-CoV-2, the virus that causes Covid-19, is likely to have originated.
Researchers believe developing treatments for such animal-borne viruses ahead of time can prove useful if those viruses make the jump to people.
“The big issue is there are a number of coronaviruses that are poised for emergence in humans,” said Aaron Lebeau, a University of Wisconsin-Madison professor of pathology.
What we’re doing is preparing an arsenal of shark VNAR therapeutics that could be used down the road for future SARS outbreaks.Aaron LeBeau, a University of Wisconsin-Madison professor of pathology
“What we’re doing is preparing an arsenal of shark VNAR therapeutics that could be used down the road for future SARS outbreaks. It’s a kind of insurance against the future.”
Lebeau and his team collaborated with researchers at the University of Minnesota and Elasmogen, a biomedical company in Scotland that is developing therapeutic VNARs.
One-tenth the size of human antibodies, the shark VNARs can bind to infectious proteins in unique ways that bolster their ability to halt infection.
“These small antibody-like proteins can get into nooks and crannies that human antibodies cannot access,” said Lebeau.
“They can form these very unique geometries. This allows them to recognise structures in proteins that our human antibodies cannot.”
The researchers tested the shark VNARs against both infectious SARS-CoV-2 and a “pseudotype” — a version of the virus that can’t replicate in cells.
They identified three candidate VNARs from a pool of billions that effectively stopped the virus from infecting human cells. The three shark VNARs were also effective against SARS-CoV-1, which caused the first SARS outbreak in 2003.
Future therapies would likely include a cocktail of multiple shark VNARs to maximise their effectiveness against diverse and mutating viruses.
“This new class of drug is cheaper and easier to manufacture than human antibodies, and can be delivered into the body through various routes, but has yet to be tested in humans.”
Lebeau is also studying the ability of shark VNARs to help in the treatment and diagnosis of cancers.