41st Annual Meeting of the Society for Invertebrate Pathology
and 9th International Conference on Bacillus thuringiensis

The discovery of Mimivirus (for “Mimicking Microbe” virus)(in 2001), a double-stranded DNA virus infecting common amoeba of the Acanthamoeba genus, followed by the analysis of its complete genome (in 2003) sent a shock wave through the community of virologists and evolutionists. By its record particle size (750 nm in diameter – see below) and genome length (1.2 million bp), the complexity of its gene repertoire (911 protein coding genes) as well as of its particle (made of the products of more than 130 virus genes), Mimivirus blurred the established boundaries between viruses and parasitic cellular organisms. As more researchers are getting involved in the study of Mimivirus, experimental information is now slowly accumulating, although very little is yet known on its physiology. I will review some of the recent progresses, including individual protein characterizations, electron microscopy, proteomics, new evidence about the ancestral origin of the Mimivirus lineage, as well as a spectacular, albeit mysterious, example of horizontal gene transfer. Our analysis of recent metagenomic data demonstrates that Mimiviridae are well represented in the sea, and strongly suggests that the closest marine mimivirus relatives are large viruses infecting algae.