Friday, June 7, 2013
With deadly new viruses emerging these days in Saudi Arabia and China, it can be hard to imagine that viruses can be good for anything. It’s easy to forget that we are home to trillions–perhaps quadrillions–of viruses on our healthiest days. And, according to a team of California scientists, those viruses are our symbiotic partners, creating a second immune system. These viruses serve as a defensive front-line, keeping bacteria from invading our gut lining and causing deadly infections.
The viruses in question are far less familiar than, say, influenza viruses or Ebola viruses. They are known as bacteriophages, which means “eater of bacteria.” And yet bacteriophages (or phages for short) are vastly more common than viruses that infect humans. They’re more common than all the viruses that infect every animal on Earth. The reason is simple arithmetic: there are far more hosts for phages to multiply in than there are for viruses that infect our own cells. They’re in the ground, in the oceans, under ice, and in the air. By some estimates, there are 1031 phages on Earth. That makes phages the most abundant life form, period.