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.
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.
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.
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.
Aiewsakun, P. and A. Katzourakis (2015). Endogenous viruses: Connecting recent and ancient viral evolution. Virology 479-480: 26-37. [PubMed]
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
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
Since only one genus is currently recognized, the genus description corresponds to the family description.
