For the first time, scientists have been able to make a real-time 3D recording of the moment a virus hijacks a cell, giving us a deeper level of understanding of how infection spreads in the body.
This microscopic nature film runs two and a half minutes long, showing a genetically sterile virus several thousand times smaller than a grain of sand traveling along a wall of human intestinal cells as it searches for an entry point.
Understanding how viruses invade cells is critical to finding better ways to defend against them, but keeping track of these particles is incredibly difficult — not least because they are much smaller than the cells they travel through.
“It’s like trying to take a picture of someone standing in front of a skyscraper,” says chemist Courtney Johnson, of Duke University in North Carolina. “You can’t get an entire skyscraper and see the person in front of it in one picture.”
Furthermore, virus particles move much faster outside the cell than inside it, making it more difficult to come up with an imaging process that is fine-tuned to handle these different sizes and speeds.
The solution in this case is a system called 3D-TrIm or 3D Tracking and Imaging Microscopy. It’s essentially two microscopes in one: the first to ‘hold’ on the fast-moving particle, and the second to take 3D images of the surrounding cells. It’s a bit like a satellite navigation app that tracks your car’s location in the middle of a broader landscape.
With the virus particle illuminated via a special fluorescent sticker, its position can be mapped 1,000 times per second, giving researchers a look at its movements through a key period in the infection process in unprecedented detail.
In the Duke University video below, the zigzag path of the virus can be seen as a purple squiggly line.
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“Sometimes when I present this work, people ask, ‘Is this a video game or a simulation?'” says Johnson. “No, that is something that came from a real microscope.”
We all breathe in millions of viruses every day, and the vast majority fail to do any harm—but scientists want to know more about how some viruses breach the protective layer of cells and mucus that covers our airways and intestines to create an infection.
This new 3D-Trim method should help, though it has its limitations: Virus particles must be tagged before imaging in order to be seen, and the fluorescent dye on them must be designed to last long enough for researchers to track the entire infection process.
However, the team behind 3D-Trim says there is potential to rapidly improve the system, adapting to other types of medical diagnostics – whether that’s monitoring viruses or monitoring drug delivery.
“Importantly, the application of this technique could be extended to any system in which rapid dynamics of nanoobjects occurs at large volume scales, including nanoscale delivery of drug candidates into the lungs and through leaky tumor vasculature,” the researchers wrote in their published paper.
Research published in nature ways.
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