Proteomic analysis of virion and genomic fibre of Mimivirus reunion

Mimivirus is the prototype of the Mimiviridae family of giant dsDNA viruses, initially isolated in Acanthamoeba. Little is known about the organization of the viral genome inside the membrane limited nucleoid and whether unpacking or other rearrangements are required prior to early transcription and replication. Here we used Mimivirus reunion (an isolate from La Réunion Island) and showed that in vitro opening of its large icosahedral capsid leads to the release of electron dense, 30 nm diameter rod-shaped objects that appear to be expelled and unwinding from the particles. We developed a purification procedure and performed a mass spectrometry-based characterization of the protein content of the genomic fibre, as well as total virion.