In a single drop of water from Lake Ontario, you can find an abundance of algae. In these algae, scientists in 2015 found a new virus belonging to an enigmatic group called giant viruses. And nested inside these giant viruses, scientists have now found yet more novel viruses—three tiny ones that they have named CpV-PLV Larry, Curly, and Moe.
“I originally named them to see if I can get away with it,” says Joshua Stough, now a postdoctoral research fellow at the University of Michigan. He’s a co-author of a new paper describing and naming the Three Stooges, so, in fact, he has gotten away with it.
All three of these viruses are what are known as virophages, viruses that specialize in infecting other viruses. Virophages were first discovered infecting giant viruses from a water-cooling tower in 2008. Since then, scientists have isolated only a handful more—all from giant viruses that infect microscopic organisms such as algae or amoebas. It’s a virus inside a virus inside a cell. “They’re like the Russian doll,” says Curtis Suttle, a virologist at the University of British Columbia who was not involved with the new study.
Giant viruses themselves are strange and poorly understood. Viruses are traditionally considered not to be alive, because they are unable to reproduce on their own like bacteria or multicellular organisms. But giant viruses seem to blur the line between alive and dead—some are almost as big as bacteria, and their genomes sometimes have many of the genes necessary for replication. What’s more, bacteria can be infected by specialized viruses called bacteriophages. Giant viruses can also be infected by specialized viruses, which are of course called virophages. In some ways, giant viruses seem to have more in common with living bacteria than with a simple influenza virus.