Abstract
BackgroundEndogenous Retroviruses (ERVs) constitute approximately 8% of every human genome and are relics of ancestral infections that affected the germ line cells. The ERV-W group contributed to primate physiology by providing an envelope protein (Syncytin-1) that has been adopted for placenta development in hominoids. Expression of Human ERV-W (HERV-W) sequences is investigated for a pathological role in various human diseases.ResultsWe previously characterized ERV-W group genomic sequences in human and non-human Catarrhini species. We now investigated ERV-W-like sequences in the parvorder Platyrrhini, especially regarding two species with complete genome assemblies, namely marmoset (Callithrix jacchus) and squirrel monkey (Saimiri boliviensis). We identified in both species proviral sequences, annotated as ERV1–1 in respective genome assemblies, sharing high sequence similarities with Catarrhini ERV-W. A total of 130 relatively intact proviruses from the genomes of marmoset and squirrel monkey were characterized regarding their structural and evolutionarily relationships with Catarrhini ERV-W elements. Platyrrhini ERV-W sequences share several structural features with Catarrhini ERV-W elements and are closely related phylogenetically with the latter as well as with other ERV-W-related gammaretrovirus-like ERVs. The ERV-W group colonized Platyrrhini primates of both Callitrichidae and Atelidae lineages, with provirus formations having occurred mostly between 25 and 15 mya. Two LTR subgroups were associated with monophyletic proviral bodies. A pre-gag region appears to be a sequence feature common to the ERV-W group: it harbors a putative intron sequence that is missing in some ERV-W loci, holding a putative ORF as well. The presence of a long pre-gag portion was confirmed among all gammaretroviral ERV analyzed, suggesting a role in the latter biology. It is noteworthy that, contrary to Catarrhini ERV-W, there was no evidence of L1-mediated mobilization for Platyrrhini ERV-W sequences.ConclusionsOur data establish that ERV-W is not exclusive to Catarrhini primates but colonized both parvorders of Simiiformes, providing further insight into the evolution of ERV-W and the colonization of primate genomes.
Highlights
Endogenous Retroviruses (ERVs) constitute approximately 8% of every human genome and are relics of ancestral infections that affected the germ line cells
Collection of ERV-W-like proviral sequences from marmoset and squirrel monkey genome sequence assemblies As detailed in materials and methods, ERV-W-like sequences present in marmoset and squirrel monkey genome assemblies – named ERV1–1 according to RepBase – were previously retrieved from UCSC Genome Browser [21] by BLAT searches [22] using Human ERV-W (HERV-W) group reference sequences (HERV17 and LTR17) obtained from RepBase Update [23] as a query [15]
A Blat search in each of those vertebrate genome assemblies using the proviral consensus previously built from marmoset and squirrel monkey datasets as a query [15] did not establish significant sequence similarities, corroborating that ERV-W is limited to certain primate lineages, as described before [14, 15], and appears to be present in marmoset and squirrel monkey, with respective sequences annotated as ERV1– 1 elements
Summary
Endogenous Retroviruses (ERVs) constitute approximately 8% of every human genome and are relics of ancestral infections that affected the germ line cells. Expression of Human ERV-W (HERV-W) sequences is investigated for a pathological role in various human diseases. Endogenous Retroviruses (ERVs) are integrated DNA relics from retroviral infections that affected mammalian ancestors for at least 100 million years (my) [1, 2]. Such infections have been caused by exogenous retroviruses mostly gone extinct – that targeted germ line cells, resulting in stably inherited proviruses in those host genomes. HERV-W Env overexpression led to development of allergic encephalomyelitis in mice [11], while treatment with a monoclonal antibody against HERV-W Env rescued myelin expression [12], a phenomenon currently investigated as an innovative clinical approach for treating MS [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
