Scientists Find Natural Protein That Blocks COVID-19 Infection

A man wearing a face mask walks before the Harbour Bridge in Sydney, NSW, Australia on July 22, 2020. Saeed Khan/AFP via Getty Images

The human body has a natural defence against COVID-19 which scientists at the University of Sydney say could pave the path for future vaccines against newer strains.

The team discovered that the body contains a naturally occurring protein, the leucine-rich repeat-containing protein 15 (LRRC15), which ties itself to the COVID-19 virus and does not pass it on to other cells.

“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,” said Professor Greg Neely, who conducted the research along with PhD researcher Lipin Loo and Matthew Waller from the Charles Perkin Centre.

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

Loo said, “We think this newly identified protein could be part of our body’s natural response to combating the infection, creating a barrier that physically separates the virus from our lung cells most sensitive to COVID-19.”

Neely told The Epoch Times the amount of LRRC15 in a person’s body determined how serious a person’s COVID symptoms could be, noting the new research could potentially be used to deal with long COVID.

“We are hoping to take this knowledge and use it to create new therapies for long COVID that involve lung fibrosis,” he said in an email.

He also noted that it might not help Long COVID sufferers with the “brain fog component yet.”

The team worked with the researchers at Oxford University in the United Kingdom, as well as Yale and Brown Universities in the United States.

What Does LRRC15 Do to COVID?

The COVID-19 virus infects humans through a spike protein called the angiotensin-converting enzyme 2 (ACE2) receptor which allows it to enter human cells.

Lung cells tend to have high levels of the ACE2 receptors, which is why the virus targets and causes problems for people in this area.

LRRC15 is similar to ACE2 in that it is also a receptor for the COVID-19 virus.

However, the difference with LRRC15 is that it does not support infection. In fact, it sticks to the virus and immobilises it while also preventing other, more vulnerable cells from being infected.

“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,” Loo 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,” said Waller from the Charles Perkin Centre.

LRRC15 is common in several parts of the body, including the lungs, skin, tongue, fibroblasts, placenta, and lymph nodes.

Researchers found, however, that it was the lungs that responded most prominently to infection.

“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,” Loo said.

Left: Control Lung. Right: Immunofluorescent staining shows the expression of new SARS-CoV-2 spike-receptor LRRC15 (green) in post-mortem lung tissue section from individuals with COVID-19. Courtesy of Loo and Waller et al. at the University of Sydney

The team hope the finding of the gene could push further development of antiviral and antifibrotic medicines to deal with future strains or potential lung fibrosis.

“For fibrosis, there are no good drugs: for example, idiopathic pulmonary fibrosis is currently untreatable,” Neely said.

COVID-19 can cause fibrosis to occur by inflaming the lungs leaving them scarred and thickened, resulting in breathing difficulties.

Victoria Kelly-Clark contributed to this report.