None of this is observable directly the system is simply too small to be seen in action. But the researchers could infer what was happening by looking at slight changes in the current across the pore.
"When the viruses miss, they rattle around and we see these little bumps in the current," Stein said. "So with these little bumps, we're starting to get an idea of what the molecule is doing before it slides through. Normally these sensors are blind to anything that's going on until the molecule slides through."
That would have been impossible to observe using DNA. The floppiness of the DNA molecule allows it to go through a pore in a folded configuration even if it's not aligned head-on. But because the virus is stiff, it can't fold to go through. That enabled the researchers to isolate and observe those contact dynamics.
"These viruses are unique," Stein said. "They're like perfect little yardsticks."
In addition to shedding light on basic physics, the work might also have another application. While the fd virus itself is harmless, the bacteria it infects e. coli is not. Based on this work, it might be possible to build a nanopore device for detecting the presence of fd, and by proxy, e. coli. Other dangerous viruses Ebola and Marburg among them share the same rod-like structure as fd.
"This might be an easy way to detect these viruses," Tang said. "So that's another potential application for this."
|Contact: Kevin Stacey|