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For the first time ever, “vampire viruses” have been discovered by a team of scientists in soil samples from Maryland and Missouri.
No, sorry, they aren’t viruses that turn humans into vampires. They are viruses that prey on other viruses, latching on to them and then using them to replicate themselves.
“When a virus enters a cell, it can either go dormant or start replicating right away. When replicating, the virus essentially commandeers the molecular factory of the cell to make lots of copies of itself, then breaks out of the cell to set the new copies free,” explained Ivan Erill, professor of biological sciences at University of Maryland, Baltimore County (UMBC).
“Sometimes a virus enters a cell only to find that its new temporary dwelling is already home to another dormant virus. Surprise, surprise. What follows is a battle for control of the cell that can be won by either party.
“But sometimes a virus will enter a cell to find a particularly nasty shock: a viral tenant waiting specifically to prey on the incoming virus.”
“When I saw it, I was like, ‘I can’t believe this,'” said UMBC biologist and lead author Tagide deCarvalho.
“No one has ever seen a bacteriophage – or any other virus – attach to another virus.”
Undergraduate phage hunters at the University of Maryland, Baltimore County isolated a satellite phage called MiniFlayer from the soil bacterium Streptomyces scabiei. MiniFlayer was found in close association with a helper virus called bacteriophage MindFlayer that infects the Streptomyces bacterium. But further research revealed that MiniFlayer was no ordinary satellite.
MiniFlayer is the first satellite phage known to have lost its ability to lie dormant. Not being able to lie in wait for your helper to enter the cell poses an important challenge to a satellite phage. If you need another virus to replicate, how do you guarantee that it makes it into the cell around the same time you do?
MiniFlayer addressed this challenge with evolutionary aplomb and horror-movie creativity. Instead of lying in wait, MiniFlayer has gone on the offensive. Borrowing from both “Dracula” and “Alien,” this satellite phage evolved a short appendage that allows it to latch onto its helper’s neck like a vampire. Together, the unwary helper and its passenger travel in search of a new host, where the viral drama will unfold again. We don’t yet know how MiniFlayer subdues its helper, or whether MindFlayer has evolved countermeasures.
The scientists say this discovery “has the potential to open new avenues for antiviral therapy.”
A paper further detailing this discovery by the researchers at UMBC, along their with colleagues from Washington University in St. Louis, was recently published in the Journal of the International Society of Microbial Ecology.