A bacteriophage, a virus that only attacks bacteria, delivers its genes into a bacterial cell.
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Viruses, like movie villains, operate in one of two ways: chill or kill.
They can lie low, quietly infiltrating the body’s defenses, or go on the attack, making many copies of themselves that explode out of hiding and fire in all directions. Viral attacks are almost always suicide missions, ripping apart the cell that the virus has been depending on. The attack can only succeed if enough other healthy cells are around for the the newly emerging viruses to infect. If the barrage of viral particles hits nothing, the virus cannot sustain itself. It doesn’t die, since viruses aren’t technically alive, but it ceases to function.
So for a virus, the key challenge is deciding when to flip from chill mode into kill mode.
Four years ago, Princeton biologist Bonnie Bassler and her then-graduate student Justin Silpe discovered that one virus has a key advantage: it can eavesdrop on the communication between bacteria. Specifically, it listens for the “We have a quorum!” chemical that bacterial cells release when they have reached a critical number for their own purposes. (The original discovery of this bacterial communication process, called quorum sensing, has led to a string of awards for Bassler and her colleagues.)
Now Bassler, Silpe and their research colleagues have found that dozens of viruses respond to quorum-sensing or other chemical signals from bacteria. Their work appears in the current issue of Nature. ...
