Giant Viruses from Amoeba in a Post-Darwinist Viral World

Amoebae are phagocytic protists that allow intracellular bacteria, fungi and viruses to live sympatrically (in the same niche) and thus make it possible and easy for them to exchange genes. They constitute a remarkable tool to study pathogenic bacteria. The use of these amoebae has been critical in isolating Legionella pneumophila strains and studying their pathogenicity [5] . Using this tool, T. Rowbotham began a collection of microorganisms that he thought were associated with pneumonias and considered these as ‘ Legionella like amoebal pathogens’ [6] . For many years, our team has studied amoebae [7, 8] in order to evaluate whether or not they can be used as a reservoir, or Trojan horse, for intracellular bacteria. The study of Rowbotham’s collection enabled us, along with La Scola et al. [9] , to identify Mimivirus for the first time; this virus resisted our attempts at identification with universal bacterial primers. Starting with this work, we obtained and described three new viral families isolated from amoebae: Mimiviridae, Marseillevirus and the virophage [10, 11] . Obtaining the genome of these viruses made it possible to test for them in metagenomic databanks, and we discovered that these viruses are almost ubiquitous and found in the majority of unfiltered databank samples [11, 12] . We have therefore devoted this special issue of Intervirology to Mimivirus, the giant virus of amoebae. The articles presented in this issue cover various aspects of Mimivirus and other giant viruses of amoebae. Thomas and Greub discuss the role of amoebae in relation to bac