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