The boiling hot, acidic conditions of Yellowstone’s hot springs might not seem like a place for life to survive, but surprisingly it thrives there. And with this life, a microbial ecosystem has developed, including viruses that prey on the bacteria, archaea, and algae.
A new study delving into these extreme viruses has uncovered how they endure these conditions, and could help in the development of nanobots to deliver drugs to cancerous tissue.
The study, published in the Proceedings of the National Academy of Sciences, focuses on the Acidianus tailed spindle virus, or simply Acidianus for short. There are three common shapes for viruses to take, either spherical, cylindrical, or lemon-shaped. While the structures of the first two have been well studied, the construction of the lemon-shaped viruses remain less well understood.
Acidianus falls into this latter category, meaning that by studying the virus that makes a living in Yellowstone’s hot springs, the researchers have been able to uncover a completely novel way in which viruses operate in building particles and interacting with host cells.
“We have understood for many years the principles for the construction of cylindrical and spherical viruses, but this is the first time we have really understood how the third class of viruses is put together,” explains co-author Martin Lawrence in a statement.
The ability to study these infectious agents has been vastly helped by the development of cryo-electron microscopy, which has sparked something of a revolution among microbiologists. The new imaging technique, which won the 2017 Nobel Prize in chemistry, allows scientists to not only picture proteins and structures, but even the individual atoms of which they are made.
For this latest study, the technique – in combination with X-ray crystallography – allowed the team of scientists to figure out exactly how the shell of Acidianus is created. “We now understand how this third kind of virus shell is assembled and the dynamic process it uses to carry and then eventually eject the DNA that it is carrying,” says Lawrence. “This understanding could potentially be adapted for technological uses.”
The Acidianus virus makes its “remarkable transition” from lemon-shaped into long, thin cylinders when it interacts with host cells via a structure that Lawrence describes as akin to bricks linked by ropes. This allows the virus to rapidly change shape when necessary. Not only that, but when the ropes slide against each other, they “squirt the DNA from the virus into the cell that the virus is infecting.”
The researchers think that by understanding how the viruses manage these shape-shifting moves, as well as how they inject their DNA in such extreme environments, it could inform the development of nanobots that precisely inject drugs into specific sites of delivery.