University of Sydney researchers have discovered a protein in the lung that blocks SARS-CoV-2 infection and forms a natural protective barrier in the human body.
This leucine-rich repeat-containing protein 15 (LRRC15), is an inbuilt receptor that binds the SARS-CoV-2 virus without passing on the infection.
The research opens up an entirely new area of immunology research around LRRC15, offering a promising pathway to develop new drugs to prevent viral infection from coronaviruses like COVID-19 or deal with fibrosis in the lungs.
The University of Sydney study is one of three independent papers that reveal this specific protein’s interaction with COVID-19.
Study lead Professor Greg Neely of the at the Charles Perkins Centre and the School of Life and Environmental Sciences, said:
“We found that this new receptor acts by binding to the virus and sequestering it which reduces infection,” Professor Neely said.
“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.
“We can now use this new receptor to design broad acting drugs that can block viral infection or even suppress lung fibrosis.”
The LRRC15 can stick to the virus and immobilise it. In the process, it prevents other vulnerable cells from becoming infected, as Dr Lipin Loo explains.
“We think it acts a bit like Velcro, molecular Velcro, in that it sticks to the spike of the virus and then pulls it away from the target cell types,” he said.
“Basically, the virus is coated in the other part of the Velcro, and while it’s trying to get to the main receptor, it can get caught up in this mesh of LRRC15,” Mr Waller added
The researchers said they are developing two strategies against COVID-19 using LRRC15 that could work across multiple variants – one which targets the nose as a preventative treatment, and another aimed at the lungs for serious cases.
The scientists also said that the presence or lack of LRRC15, which is involved in lung repair, is an important indication of how severe a COVID-19 infection might become.
Dr Loo said:
“A group at Imperial College London independently found that absence of LRRC15 in the blood is associated with more severe COVID, which supports what we think is happening.
“If you have less of this protein, you likely have serious COVID. If you have more of it, your COVID is less severe.
“We are now trying to understand exactly why this is the case.”
