Science Daily reports that a team of scientists from Tokyo University and Kyoto University have discovered a giant virus that can turn amoebas into hard cysts. Hence the name "medusavirus" because just like the mythical being, Medusa, it turns things into stone, or in this case hard cysts. The the team was led by virologist Masaharu Takemura and Hiroyuki Ogata.
They discovered that the medusavirus DNA replicated in the nucleus of the amoeba host and observed genetics information being exchanged between the two. The virus was also discovered to have some of the building blocks for eukaryotes hidden in their genome. They think that there is a likely connection between the virus and the origin of eukaryotes. The virus itself can't replicate and needs to use the tools provided by the host cell. The host and virus can co-evolve with the virus leaving around clues that are passed down from generation to generation. And although the virus uses the host cell to replicate it does use its own polymerase and histones. This could mean that our own DNA polymerase could have originated from something related to the virus.