For the first time, scientists have been able to make a three-dimensional, real-time recording of the moment a virus hijacks a cell, giving us a deeper level of understanding of how infections take hold in the body. 

The microscopic nature film lasts two-and-a-half minutes, and shows a genetically sterile virus many thousands of times smaller than a grain of sand traveling along a wall of human intestinal cells as it looks for an entry point. 

Understanding how viruses break into cells is crucial in working out better ways of defending against them, but tracking these particles is incredibly difficult – not least because they are so much smaller than the cells they're navigating. 

"It's like you're trying to take a picture of a person standing in front of a skyscraper," says chemist Courtney Johnson, from Duke University in North Carolina. "You can't get the whole skyscraper and see the details of the person in front of it with one picture." 

What's more, virus particles move much faster outside the cell than inside it, making it even trickier to come up with an imaging process that is fine-tuned to cope with these varying sizes and speeds. 

The solution in this case is a system called 3D-TrIm, or 3D Tracking and Imaging Microscopy. It's basically two microscopes in one: the first to 'lock on' to the fast-moving particle, and the second to capture 3D pictures of the surrounding cells. 

It's a little bit like a satellite navigation app tracking your car's location in the middle of a wider landscape. 

With the virus particle illuminated via a special fluorescent label, it's position can be plotted 1,000 times a second, giving researchers a look at its movements across a key period in the infection process in unprecedented detail.