virus (PoV) Tetraselmis virus (TetV-1) This group seems to be closely related to Mimiviridae rather than to Phycodnaviridae and therefore is sometimes referred to as a further subfamily candidate Mesomimivirinae. Sometimes the extended family Mimiviridae is referred to as Megaviridae although this has not been recognized by ICTV; alternatively the extended group may be referred to just as Mimiviridae. With recognition of new order Imitervirales by the ICTV im march 2020 there is no longer need to extend the Mimiviridae family to comprise a group of viruses of the observed high diversity. Instead, the extension (or at least its main clade) may be referred to as a sister family Mesomimiviridae. Although only a couple of members of this order have been described in detail it seems likely there are many more awaiting description and assignment Unassigned members include Aureococcus anophagefferens virus (AaV), CpV-BQ2 and Terra2. Structure Viruses in Mimiviridae have icosahedral and round geometries, with between T=972 and T=1141, or T=1200 symmetry. The diameter is around 400 nm, with a length of 125 nm. Genomes are linear and non-segmented, around 1200kb in length. The genome has 911 open reading frames. Life cycle Replication follows the DNA strand displacement model. DNA-templated transcription is the method of transcription. Amoeba serve as the natural host. Molecular biology Within the genome of Lentille virus integrated genome of a virophage (Sputnik 2) and a transpoviron—a mobile genetic element—have been reported. Transpovirons are linear DNA elements of about 7 kilobases that encompass six to eight protein coding genes, two of which are homologous to virophage genes. Broad spectrum of mimiviridae virophage allows its isolation using a mimivirus reporter. Clinical Mimiviruses have been associated with pneumonia but their significance is currently unknown. The only virus of this family isolated from a human to date is LBA 111. At the Pasteur Institute of Iran (Tehran), researchers identified mimivirus DNA in bronchoalveolar lavage (BAL) and sputum samples of a child patient, utilizing real-time PCR (2018). Analysis reported 99% homology of LBA111, lineage C of the Megavirus chilensis. With only a few reported cases previous to this finding, the legitimacy of the mimivirus as an emerging infectious disease in humans remains controversial. Mimivirus has also been implicated in rheumatoid arthritis. See also Virophage References External links Viralzone: Mimiviridae ICTV Virus families