When scientists first encountered Mimivirus within amoebae, they thought it was a bacterium because of its size. Much to their surprise, electron microscopy revealed that the organism infecting these amoebae was in fact giant viruses. “A giant virus is like a bacterium but with a capsid and without ribosomes. This is the only difference,” said Bernard La Scola from Aix-Marseille University, who helped discover the virus.
Seven years ago, La Scola’s team realized that this giant virus could be infected by a smaller virus—a virophage called Sputnik. Later they discovered another virophage called Zamilon. Now, using this virophage as a unique tool, the team has discovered a CRISPR-like defense system, the Mimivirus virophage resistance element (MIMIVIRE), which they described in Nature. Rest