Virus classification e
(unranked): Virus
Realm: incertae sedis
Kingdom: incertae sedis
Phylum: incertae sedis
Class: incertae sedis
Order: incertae sedis
Family: Pospiviroidae

See text

The Pospiviroidae[1] are a family of viroids, including the first viroid to be discovered, PSTVd. Their secondary structure is key to their biological activity. The classification of this family is based on differences in the conserved central region sequence.[2] The genome consists (in this order) of an LH terminal domain, a pathogenic domain, conserved central region (pospiviroid RY motif stem loop), variable domain, and an RH terminal domain.[3] Pospiviroidae replication occurs in an asymmetric fashion via host cell RNA polymerase, RNase, and RNA ligase.


The family contains the following genera:[4]


  1. ^ Di Serio, F; Owens, RA; Li, SF; Matoušek, J; Pallás, V; Randles, JW; Sano, T; Verhoeven, JTJ; Vidalakis, G; Flores, R; ICTV Report Consortium (17 December 2020). "ICTV Virus Taxonomy Profile: Pospiviroidae". The Journal of General Virology. doi:10.1099/jgv.0.001543. PMID 33331814.
  2. ^ "ICTV Report Pospiviroidae".
  3. ^ Giguère, Tamara; Perreault, Jean-Pierre; Melcher, Ulrich (4 August 2017). "Classification of the Pospiviroidae based on their structural hallmarks". PLOS ONE. 12 (8): e0182536. doi:10.1371/journal.pone.0182536. PMID 28783761. Most of the members of the Pospiviroidae fold into a rod-like structure which includes five regions: the terminal left (TL), the pathogenic (P), the central (C), the variable (V) and the terminal right (TR).
  4. ^ "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 24 May 2021.