If he were starring in a campy horror flick, Tim Rowbotham might have gasped and whispered, “It’s alive!” As a microbiologist with Britain’s Public Health Laboratory Service, he had isolated an unknown microorganism from an amoeba growing in a water tower in Bradford, England. Rowbotham baptized the entity “Bradford coccus.” He added his new specimen to the collection of bacteria that live within amoebas and continued the search for the cause of a pneumonia outbreak plaguing the citizens of Bradford.
But Rowbotham hadn’t discovered a bacterium. He had actually found a gigantic virus—one so large and possessing such a peculiar mixture of traits that it is challenging the very notion of what it means to be alive.
Viruses have long been regarded as nonliving entities. They don’t have the machinery to make new viruses, nor do they have a discernible metabolism (you won’t hear a virus declare “as I live and breathe,” and not just because they don’t have mouths). Viruses are typically thought to barely have genetic material to call their own, characterized instead as ghostly gene-thieves who prey upon and steal from real organisms. But as scientists shine the spotlight on the shadow economy of the virus world, a new vision of viruses is emerging. Rather than furtive thieves, viruses are more like commodities dealers, playing a major role in transferring genes from one organism to another. The acquisition of new genes may dramatically alter the lifestyle of the organism that gets the goods, allowing it to invade a new environment, for example, or fight off predators.
Viruses also may keep genes they’ve procured, and even bundle these assets together, as appears to be the case with several photosynthesis genes recently found in marine viruses. These finds hint at the vast viral contribution to the ocean’s gross national product and viruses’ significance in global energy production.
“Viruses are major drivers of nutrient and energy cycles on the planet,” says marine virologist Curtis Suttle of the University of British Columbia in Vancouver, Canada.
This increased appreciation of the viral influence on cellular life today is reviving debate about the role viruses may have played in the planet’s primordial days, scientists say. Viruses may even be at the root of the cellular tree of life, participating in the evolution of the eukaryotic nucleus.
“Viruses are and have been a main force in the evolution of life on the planet,” says Jean-Michel Claverie of the Mediterranean Institute of Microbiology in Marseille, France. “They remain a leading force in the cellular world.”
Of course, part of that force is virus as bad guy. From the common cold to influenza to Ebola, viruses have long been recognized as agents of illness and death. Viruses infect all domains of life—from plants and animals to protists and bacteria. In fact, viruses lurk behind many ailments blamed on bacteria. For example, the bacterium that causes diphtheria does so only when it carries a virus.
Scientists have long been well acquainted with the nefarious activities of these viruses of doom, but now a more productive view of death by virus is emerging. Viruses don’t just kill plants and animals—they kill the organisms at the bottom of the food chain, deaths that have dramatic implications. “If you take viruses out of seawater, counterintuitively, things stop growing,” Suttle says. In death, victims of viruses release nutrients. “Their killing feeds the world.”
White cliffs of death