Canadian researchers discover 'spider web' mechanism that can trap, kill viruses

TORONTO -

A group of Canadian immunologists have discovered a previously unknown mechanism, which they say acts like a spider web to trap and kill pathogens including influenza or SARS-CoV-2, the virus that causes COVID-19.

Researchers out of McMaster University in Hamilton, Ont. found that neutrophils, the most abundant white blood cells in the human body, "explode" when they bind to these antibody-coated pathogens in the respiratory tract and release DNA outside of the cell, creating a "sticky tangle" that serves as a trap.

According to the study, neutrophil extracellular traps (NETs) are also capable of inactivating viruses, similar to that of an antiviral function.

The findings were published Tuesday in peer-reviewed journal Proceedings of the National Academy of Science.

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The immunologists say the discovery of these NETs is significant as there has been limited prior knowledge of how antibodies neutralize viruses in the respiratory tract. The study noted that NETs have mostly been studied as an antipathogen immune response in the context of bacterial infections, until now.

Researchers say the discovery could aid in future vaccine design and delivery, including aerosol and nasal spray technologies that could help the body fend off infections before they fully take hold.

"Vaccines can produce these antibodies that are present in our lungs, which are the first type of antibody to see viruses like flu or COVID-19, which infect our lungs and respiratory tracts," McMaster associate professor and the study's lead author Matthew Miller said in a press release.

"Mechanisms that can stop the infection at the site where it enters our body can prevent the spread and serious complications," he added.

In comparison, graduate student and lead author of the paper Hannah Stacey explained that injectable vaccines are designed to boost antibodies in one's blood.

"If you want a lot of these antibodies that are really abundant in blood, then injections make the most sense, but if you want antibodies that are abundant in the respiratory tract, then a spray or an aerosol makes sense," Stacey said in the release.

However, she noted that those blood antibodies are not as prevalent at the sites where the infection first starts.

"We should be thinking carefully about next generation COVID-19 vaccines that could be administered in the respiratory tract to stimulate antibodies. We don't have many candidates right now that are focused on raising the mucosal response," Stacey said.

While the body's spider-web mechanism has the potential to benefit in the fight against infection, experts warn that it can also cause harm, including increased inflammation and further illness if the web formation is "uncontrollable."

Researchers noted that this was seen during early waves of the COVID-19 pandemic, prior to vaccines, when some patients where found to have neutrophil extracellular traps in their lungs, making their breathing more difficult.

"It's important to understand the balance of the immune system. If you have a lot of these antibodies before you get infected, they are likely going to protect you, but if the infection itself stimulates a lot of those antibodies it might be harmful," Miller said.