Endogenous foamy viruses
| Spumaretrovirinae | |
|---|---|
 | |
| EndFVs were first identified in the two-toed sloth. | |
Virus classification  | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Pararnavirae |
| Phylum: | Artverviricota |
| Class: | Revtraviricetes |
| Order: | Ortervirales |
| Family: | Retroviridae |
| Subfamily: | Spumaretrovirinae |
| Synonyms | |
| |
Endogenous foamy viruses (EndFVs) are endogenous retroviruses derived from members of the subfamily Spumaretrovirinae that have been endogenized into a host's germline DNA and are vertically inherited. Like other ERVs, they represent molecular fossils of ancient foamy virus infections and are defective, typically containing frameshift mutations and premature stop codons.[1][2] EndFVs are comparatively rare among endogenous retroviruses,[3] and their phylogenetic relationships with host species provide evidence for long-term virus-host co-divergence in several lineages, though cross-species transmission events may have also occurred.[4][3][5]
Distribution
Endogenous foamy viruses were first identified in the genome of the two-toed sloth in 2009, suggesting a close association between foamy viruses and their mammal hosts maintained for over 100 million years.[4] EndFV-like elements were subsequently identified in the genome of the coelacanth, indicating that foamy viruses may have a long evolutionary history predating the divergence of sarcopterygii and tetrapods.[6] An EndFV was identified in the aye-aye, a strepsirrhine primate, with the only known exogenous foamy virus that infects any lemuriform being the Brown greater galago prosimian foamy virus. The divergence from known simian foamy viruses is consistent with an association between foamy viruses and primates since the haplorrhine-strepsirrhine split approximately 85 million years ago.[7] Another EndFV present in the Cape golden mole suggests continuous foamy virus presence since the most recent common ancestor of all placental mammals, and that all major placental mammal clades have been infected.[8]
Spumavirus-related EndFV-like elements have also been described in ray-finned fishes, Maguari storks, tuataras, among others.[8][9] In the Maguari storks, incongruence between the virus and host phylogenies indicates that integration occurred independently via cross-species transmission.[3] Proviruses related to foamy viruses have been reported across various vertebrate groups, including species with no known spumaviruses.[1]
Genome
EndFVs retain the basic genomic organization of exogenous foamy viruses, with long terminal repeats flanking three open reading frames encoding genes gag, pol, and env.[5][3] The tuatara and avian EndFVs also contain an additional open reading frame with no clear similarity to the accessory genes (tas, bet) of the normal exogenous foamy viruses.[5][3]
Evolution
Distribution of EndFVs across vertebrate classes, combined with evidence for host co-evolution in multiple lineages, suggests foamy viruses have a deep evolutionary history potentially spanning hundreds of millions of years.[4][5][6] Discordance between the topologies of some host and viral lineages, notably in birds, points to at least some interspecies transfer events during foamy virus evolution.[4][3] Known EndFV copies are present at low copy numbers in host genomes, demonstrating the rarity of foamy virus germline integration relative to other retroviral groups.[3]
See also
References
- 1 2 "Spumaretrovirinae". International Committee on Taxonomy of Viruses. Retrieved 17 May 2026.
- ↑ Gardner, Murray B.; Luciw, Paul A. (2004). "Simian Retroviruses". In Wormser, Gary P. (ed.). AIDS and Other Manifestations of HIV Infection (4th ed.). Elsevier. ISBN 9780127640518.
- 1 2 3 4 5 6 7 Chen, Yicong; Wei, Xiaoman; Zhang, Guojie; Holmes, Edward C.; Cui, Jie (2019). "Identification and evolution of avian endogenous foamy viruses". Virus Evolution. 5 (2) vez049. doi:10.1093/ve/vez049. PMC 6875641. PMID 31777663.
- 1 2 3 4 Mourikis, T.P.; Aswad, A.; Katzourakis, A. (2016). "Endogenous Retroviruses and Coevolution". Encyclopedia of Evolutionary Biology. Elsevier. pp. 498–504. doi:10.1016/B978-0-12-800049-6.00192-X. ISBN 978-0-12-800426-5.
- 1 2 3 4 Wei, Xiaoman; Chen, Yicong; Duan, Guangqian; Holmes, Edward C.; Cui, Jie (2019). "A reptilian endogenous foamy virus sheds light on the early evolution of retroviruses". Virus Evolution. 5 (1) vez001. doi:10.1093/ve/vez001. PMC 6393741. PMID 30838130.
- 1 2 Han, Guan-Zhu; Worobey, Michael (2012). "An Endogenous Foamy-like Viral Element in the Coelacanth Genome". PLOS Pathogens. 8 (6) e1002790. doi:10.1371/journal.ppat.1002790. PMC 3386198. PMID 22761578.
- ↑ Han, Guan-Zhu; Worobey, Michael (2012). "An Endogenous Foamy Virus in the Aye-Aye (Daubentonia madagascariensis)". Journal of Virology. 86 (14): 7696–7698. doi:10.1128/JVI.00650-12. PMC 3416287. PMID 22573860.
- 1 2 Han, Guan-Zhu; Worobey, Michael (2014). "Endogenous Viral Sequences from the Cape Golden Mole (Chrysochloris asiatica) Reveal the Presence of Foamy Viruses in All Major Placental Mammal Clades". PLOS ONE. 9 (5) e97931. Bibcode:2014PLoSO...997931H. doi:10.1371/journal.pone.0097931. PMC 4024004. PMID 24835242.
- ↑ Xu, Xiaoyu; Zhao, Huayao; Gong, Zhen; Han, Guan-Zhu (2018). "Endogenous retroviruses of non-avian/mammalian vertebrates illuminate diversity and deep history of retroviruses". PLOS Pathogens. 14 (6) e1007072. doi:10.1371/journal.ppat.1007072. PMC 6001957. PMID 29902269.