Video: Watch this microscopic virus try to infect a cell
In a stunning feat of microscopy, scientists have been able to produce a video showing a tiny virus circulating around cells prior to infection.
"What we find is that the virus will have many transient contacts, very short timescale contacts, with many cells before binding on any one cell in particular," said Kevin Welsher, an associate professor of chemistry at Duke University, in an interview with Quirks & Quarks host Bob McDonald.
The improvement over previous techniques for capturing this kind of activity is like the difference between a modern Hollywood movie and a stuttering flip book.
Welsher said he and his colleagues have been developing this technique for seven years, and published their findings in the journal Nature Methods.
Their breakthrough came when they figured out how to track the virus as it moved among the three-dimensional layers of epithelial cells. These are the cells that line body surfaces, like in the nose, lungs and gut, that are the first to come into contact with viruses.
Scientists are eager to gather more detail about how viruses hijack these cells, so this new 3D microscopy could improve their ability to observe the process unfold.
Welsher describes the virus' motion as a "random walk" in which heat energy manifests as small, random motions in all three dimensions. That, over time, propels the tiny virus particles around the extracellular medium.
"Before what we were doing here, the common way to look at a three-dimensional system was to take images of each slice of the system and build it into an overall volume," Welsher explained.
But the time it takes the camera, with its fixed field of view, to move to different angles to capture the next frame of the moving target means they miss details about the rapidly moving virus they're trying to capture.
That's valuable imaging information that doesn't get recorded, which Welsher said their new technique reveals.
They do this by locking the camera's field of view onto the viral target, much like a helicopter in a high-speed car chase.
The research team's video only captured part of the infection process where the virus binds to the cell. Welsher said the researchers's ultimate goal is to capture the entire infection process as a virus first makes its way through the mucous layer that lines the epithelial cells, and ultimately enters a cell to replicate.