October 16th, 2012
When you think about viruses, you might wonder how they infect, how
they spread, and how they kill. These questions are of natural
interest—you, after all, could play host to a grand variety of lethal
viruses. But do remember: it’s not all about you.
A virus’ world contains not just potential hosts, but other viruses.
It has competition. This simple fact is often ignored but it has
profound implications. In a new study, Lisa Bono
from the University of North Carolina has shown that competition
between viruses can drive them to spill over into new hosts, imperilling
creatures that they never used to infect.
Rather than focusing on the viruses we know and dread, Bono worked with phi6, a virus that infects and kills bacteria. This bacteriophage
(hereafter just ‘phage’) looks like a lunar lander, that docks onto the
surface of bacteria with spindly ‘legs’ and injects its genetic
material through a syringe-like tube. Bono worked with a phage strain
that infects Pseudomonas syringae, a bacterium that causes disease in plants. It favours this species above all others.