Pseudoviridae

Pseudoviridae is a family of viruses,[1] which includes the following genera:[2]

  • Genus Pseudovirus; type species: Saccharomyces cerevisiae Ty1 virus
  • Genus Hemivirus; type species: Drosophila melanogaster copia virus
  • Genus Sirevirus; type species: Glycine max SIRE1 virus
Pseudoviridae
Virus classification
(unranked): Virus
Realm: Riboviria
Kingdom: Pararnavirae
Phylum: Artverviricota
Class: Revtraviricetes
Order: Ortervirales
Family: Pseudoviridae
Genera

A further Pseudoviridae species without classified genus is Phaseolus vulgaris Tpv2-6 virus.

Viruses of the family are actually LTR retrotransposons of the Ty1-copia family. They replicate via structures called virus-like particles (VLPs). VLPs are not infectious like normal virions, but they nevertheless make up an essential part of the pseudoviral lifecycle.[2]

Taxonomy

Pseudoviridae is unofficially classified under group VI RNA Reverse Transcribing Viruses and infect fungi and invertebrates.

Pseudoviridae comprises highly divergent members and most Pseudoviridae encode Gag and Pol on a single open reading frame.

Pseudoviridae is included in the order Ortervirales along with families Belpaoviridae, Metaviridae, Retroviridae, and Caulimoviridae.[3]

A species unassigned to a genus also exists: Phaseolus vulgaris Tpv2-6 virus.

Genome

The genome of viruses from this family is unsegmented, -RT, positive-sense, single-stranded RNA and is 4200–9700 nucleotides long. The genome encodes structural proteins and non-structural proteins which codes for an RNA-dependent DNA polymerase, replicase, and reverse transcriptase for the reverse transcription step during replication.

Virology

The viral capsid is unenveloped and looks roughly spherical. The capsid is round with icosahedral symmetry with triangulation number (T) = 3 and 4. It is also isometric to quasi-isometric and has a diameter of 30-50 nm. LTR-retrotransposons are poorly characterized and lipids have not reported.

The genome integrates into the host genome and gets transcribed by host cell enzymes such as eukaryotic nuclear RNA polymerase II. Genome replication takes place in the host cytoplasm, or the nucleus and assembly can occur in the cytoplasm, or in the nucleus.

References
  1. Llorens, C; Soriano, B; Krupovic, M; ICTV Report Consortium (2 February 2021). "ICTV Virus Taxonomy Profile: Pseudoviridae". The Journal of General Virology. doi:10.1099/jgv.0.001563. PMID 33528349.
  2. "ICTV Report Pseudoviridae".
  3. Krupovic M, Blomberg J, Coffin JM, Dasgupta I, Fan H, Geering AD, et al. (June 2018). "Ortervirales: New Virus Order Unifying Five Families of Reverse-Transcribing Viruses". Journal of Virology. 92 (12). doi:10.1128/JVI.00515-18. PMC 5974489. PMID 29618642.
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