Sydney researchers think they have found the body’s natural response to combating COVID-19 infection

University of Sydney scientists have identified a protein in the body capable of forming a protective barrier that could block COVID-19 infection.

The protein (known as LRRC15) works by binding the COVID-19 virus without passing on the infection.

The study is published in PLOS Biology.

“For me, as an immunologist, the fact that there’s this natural immune receptor that we didn’t know about, that’s lining our lungs and blocks and controls virus, that’s crazy interesting,” immunologist and study author Professor Greg Neely says.

“We can now use this new receptor to design broad acting drugs that can block viral infection or even suppress lung fibrosis.”

COVID-19 usually infects humans by attaching to a specific cell protein called ACE2 which is common in human lungs.

“ACE2 is kind of gateway that gets the virus into the cell,” Neely tells Cosmos.

Like ACE2, the LRRC15 protein also acts a receptor for the virus. The key difference is that when COVID-19 binds to LRRC15, this specific protein doesn’t support infection.

LRRC15 is present in the lungs, skin, tongue, fibroblasts, placenta and lymph nodes. But the researchers found human lungs light up with LRRC15 after infection.   

The researchers think it might be part of the body’s natural response to combating infection.

Independently, two other papers – one at Oxford and one at Brown and Yale in the US – revealed similar findings about the LRRC15 protein’s interaction with COVID-19.

University of Sydney postdoctoral researcher and co-author, Dr Lipin Loo, says the protein acts a bit like “molecular Velcro” sticking to the virus and immobilising it.

“When we stain the lungs of healthy tissue, we don’t see much of LRRC15, but then in COVID-19 lungs, we see much more of the protein,” Dr Loo says.

The researchers say the findings could help develop new medicines for treating viruses like COVID-19 by activating the protein’s antiviral and protective response.

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