Subfamily: Orthoretrovirinae

Genus: Epsilonretrovirus

Subfamily: Orthoretrovirinae

Genus: Deltaretrovirus

Distinguishing features

Viruses in this genus are most similar to viruses in the genus Gammaretrovirus, but can be distinguished based on RT-based phylogenetic clustering, by the presence of the regulatory genes tax and rex, and in some viruses, the unusual presence of an hbz gene on the antisense strand.

Subfamily: Orthoretrovirinae

Genus: Betaretrovirus

Distinguishing features

Virions can have “B-type” or “D-type” morphology, depending on the species. Genomes typically contain an additional regulatory gene that overlaps with the env gene and is encoded by a multiply-spliced mRNA – examples include the rem gene of MMTV and the rej gene of JSRV. 

Subfamily: Orthoretrovirinae

Genus: Alpharetrovirus

Distinguishing features

Virus particles assemble at the plasma membrane and exhibit a “C-type” morphology. Viruses in the genus have an envelope TM protein with an internal fusion peptide flanked by two cysteines, whereas viruses in the other genera typically have an N-terminal fusion peptide. Many oncogene-containing members of the genus have been isolated. 

Family: Retroviridae

Subfamily: Orthoretrovirinae

Citation: Retroviridae

A summary of this ICTV Report chapter has been published as an ICTV Virus Taxonomy Profile article in the Journal of General Virology, and should be cited when referencing this online chapter as follows:

Coffin et al., 2021, ICTV Virus Taxonomy Profile: Retroviridae 2021, Journal of General Virology, 2021;102:001712. 

References: Retroviridae

Aiewsakun, P. and A. Katzourakis (2015). Endogenous viruses: Connecting recent and ancient viral evolution. Virology 479-480: 26-37. [PubMed]

Authors: Retroviridae

Family: Retroviridae

John Coffin, Jonas Blomberg , Hung Fan, Robert Gifford, Theodora Hatziioannou, Dirk Lindemann, Jens Mayer, Jonathan Stoye, Michael Tristem, Welkin Johnson

The citation for this ICTV Report chapter is the summary published as Coffin et al., (2021):
ICTV Virus Taxonomy Profile: Retroviridae 2021, Journal of General Virology 2021;102:001712

Resources: Belpaoviridae

Websites

Gypsy Database (GyDB) focusing on members of the order Ortervirales and their evolutionary history: http://gydb.org

Repbase database of repetitive DNA elements: https://www.girinst.org/repbase

RepetDB a knowledge database of transposon references: http://urgi.versailles.inra.fr/repetdb