The genus Betalipothrixvirus currently only includes the virus species Sulfolobus islandicus filamentous virus and three other provisionally classified bacteriophages that reproduce exclusively in thermophilic Crenarchaeota species (family Thermoproteaceae ). The genome of Betalipothrixviren, as with all members of the virus family Lipothrixviridae of a linear, double-stranded DNA of about 41,000 base pairs . This codes for 73 virus proteins . The associated reading framesare organized in several operons that are adapted to those of the host genome. The virus particles (virions) consist of a helical, elongated capsid to which a virus envelope is attached very closely. These filamentous virions are 24 nm in diameter and 1950 nm long. At both ends of the filaments one can find tuft-like appendages, which are probably used for attachment to the target cells. Typical of the genus is the low flexibility of the virus particles, which appear as slightly curved rods in the electron microscope image. This property serves to distinguish it from the other genera of the virus family.
Species Desulfurolobus ambivalens filamentous virus (DAFV)
Species Thermoproteus Tenax Virus 2 (TTV-2)
Species Thermoproteus Tenax Virus 3 (TTV-3)
The former largest representative, the Thermoproteus tenax virus 1 (en. Thermoproteus tenax virus 1 , TTV-1), with 38 × 2200 nm one of the largest known virus species at all, has since been added to the family Tristromaviridae , genus Alphatristromavirus . There are no matches or similarities in the genome sequence between this species (TTV-1) and the beta or gammalipothrix viruses, and their filaments are not flexible.
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D. Prangishvili, T. Basta, RA Garrett: Crenarcheal Viruses: Morphotypes and Genomes . In: Brian WJ Mahy and Marc H. van Regenmortel (eds.): Encyclopedia of Virology , 3rd Edition, San Diego 2008, Volume 1, pp. 587 ff, ISBN 978-0-12-373935-3
CM Fauquet, MA Mayo, et al. : Eighth Report of the International Committee on Taxonomy of Viruses . London, San Diego, 2005, ISBN 0-12-249951-4
HP Arnold et al. : A novel lipothrixvirus, SIFV, of the extremely thermophilic crenarchaeon Sulfolobus . Virology (2000) 267 (2): pp. 252-266, PMID 10662621
