In brief
- Researchers have uncovered a viral transmission pathway that could help explain severe inflammatory responses in COVID-19 patients.
- It could help inform treatments and research to prepare for future pandemics.
More than six years after COVID-19 triggered a global pandemic, scientists are still discovering new details about how the virus behaves inside the human body.
Researchers from La Trobe University have uncovered a previously unknown pathway that allows SARS-CoV-2, the virus that causes COVID-19, to infect immune cells, triggering a powerful inflammatory response that can lead to severe lung damage.
The study found SARS-CoV-2 can hide inside dying fragments of infected cells, allowing the virus to gain access to immune cells as they engulf cellular debris during the body's natural clean-up process.
Once inside the immune cells, known as macrophages, the virus can spread to other immune cells and trigger an inflammatory response that damages lung tissue.
Kha Phan, a National Health and Medical Research Centre emerging leadership fellow at the La Trobe Institute for Molecular Science, was lead researcher in the study.
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He told SBS News the study had "uncovered a novel pathway of viral transmission".
"Our macrophages have a defence mechanism, so they get inflamed. They actually cause all of the defence mechanisms, triggering all the inflammation that we observe in COVID-19 patients," he said.
What does this mean for treatments?
Phan said the discovery will help scientists improve their understanding of what drives severe COVID-19, which makes it easier to identify more targeted treatments that can dampen the body's response.
He said applying more effective treatments earlier could help to prevent long-term complications, such as long COVID, if the initial severity of inflammation can be reduced.
"This fundamentally shifts the way we think about viral infections and solves a long-standing puzzle about how COVID-19 infects immune cells and drives severe inflammation," Phan said.
Respiratory viruses such as COVID-19, influenza and respiratory syncytial virus (RSV) continue to infect millions of people worldwide each year.
The World Health Organization estimates that the seasonal flu alone may lead to up to 650,000 deaths each year. More than seven million deaths due to COVID-19 have been reported globally since December 2019.
Phan said unknown transmission pathways could also exist in viral diseases like influenza and RSV that involve similar inflammatory processes.
"Understanding these mechanisms could help us develop more effective treatments and improve our preparedness for future viral outbreaks," he said.
Future pandemic preparedness
Stuart Turville, an associate professor at UNSW's Kirby Institute with expertise in molecular virology, told SBS News the findings will be "incredibly important for future pandemic preparedness", particularly in improving scientists' understanding of coronaviruses that infect the lungs and lower respiratory tract.
He noted, however, that the study used an early strain of SARS-CoV-2 that differs from the variants circulating today, which are more likely to infect the upper respiratory tract.
He also emphasised the importance of continued research into COVID-19.
"I think a lot of people want to forget that it ever existed, rightly so, because it caused so much disruption and damage globally," he said.
"We've got to be mindful not to be apathetic about not researching this virus anymore, because there's going to be a future similar one like this, whether it be coronavirus or another respiratory virus, that's going to have very similar traits."
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