Your Inner Lions: Get to Know Your Virome

I’ve been blogging a lot recently about dangerous viruses, like the flu and norovirus. But, truth be told, a lot of viruses we harbor don’t make us sick. They may even make us healthy. You’d think they’d be worth getting to know. But they’re mostly a mystery to us.

The collection of viruses that are dwelling inside you right now is known collectively as the virome. You might think these viruses were the sort that infect your cells. Some indeed are. There’s a good chance you harbor papillomaviruses in some of your skin cells, for example. And chances are they won’t cause you any harm. Rather than blasting apart your cells, papillomaviruses merely accelerate the rate at which your cells divide. Since you slough off your skin cells, you’re rid of the viruses soon enough anyway. No harm, no foul. The only trouble these viruses can cause is when they end up accelerating your cells until they spin out of control. They can cause cervical cancer and warts when this happens.

And yet your own cells are not the only targets for viruses. The bacteria, fungi, and other residents of your body can serve as hosts as well. Indeed, of the several million viruses in you right now, most probably infect bacteria. As Sarah Williams writes in the Proceedings of the National Academy of Sciences (open access), virologists who have charted the huge diversity of viruses in the outside world are now going inside. There’s not that much difference between us and a coral reef when you look at us as an ecosystem.

The virus survey is in its very early stages, partly because it’s trickier to identify viruses than bacteria. At this stage of the virome saga, most of the viruses that researchers dredge out of our bodies are entirely new to science. Each of us has a unique virome as well, with a unique balance of species that can change quickly. But someday they may understand the virome well enough to manipulate it for our well being. Some scientists suspect that viruses may influence our health in many ways, some obvious and some subtle. As Williams notes, a person’s virome could influence how severe unrelated diseases might be, such as asthma and cystic fibrosis.

Over at Environmental Health Perspectives, Carol Portera takes a look at another way we might harness the virome: to kill bad bacteria (also open access). The idea of using viruses to cure infectious diseases is about a century old now, but the method–known as phage therapy–has never managed to go mainstream in the West. That’s just starting to change. The FDA has approved viruses to kill infectious bacteria on food, for example. Research is fairly far along in using viruses to disinfect wounds, cure acne, and clean water supplies. If you’re worried about putting viruses in your body, relax–there are swarms of bacteria-infecting viruses in many foods you eat, such as yogurt.

Someday, once we get to know our virome much better, a new generation of scientists may study our bodies as ecologists today study lions on the savanna. Predators play a huge role in food webs, influencing the populations of a vast number of species (I wrote about this in detail in Scientific American last year). Viruses probably play a similar role in our bodies, influencing who wins and who loses in the fierce competition among thousands of species for survival inside us. Ecologists are exploring how to restore dysfunctional ecosystems by returning their predators. Perhaps we may manage our inner lions in the future.

For more information on viruses, see my book, A Planet of Viruses. And, in closing…here’s a cool video of a virus invading a bacteria. It’s really a virus, not a lunar lander.

Michael Rossman, Purdue – T4 Bacteriophage Infection from Seyet LLC on Vimeo.