Abstract
Studies of viruses that coevolved with lemurs provide an opportunity to understand the basal traits of primate viruses and provide an evolutionary context for host-virus interactions. Germline integration of endogenous retroviruses (ERVs) are fossil evidence of past infections. Hence, characterization of novel ERVs provides insight into the ancient precursors of extant viruses and the evolutionary history of their hosts. Here, we report the discovery of a novel endogenous retrovirus present in the genome of a lemur, Coquerel’s sifaka (Propithecus coquereli). Using next-generation sequencing, we identified and characterized the complete genome sequence of a retrovirus, named prosimian retrovirus 1 (PSRV1). Phylogenetic analyses indicate that PSRV1 is a gamma-type betaretrovirus basal to the other primate betaretroviruses and most closely related to simian retroviruses. Molecular clock analysis of PSRV1 long terminal repeat (LTR) sequences estimated the time of endogenization within 4.56 MYA (±2.4 MYA), placing it after the divergence of Propithecus species. These results indicate that PSRV1 is an important milestone of lemur evolution during the radiation of the Propithecus genus. These findings may have implications for both human and animal health in that the acquisition of a gamma-type env gene within an endogenized betaretrovirus could facilitate a cross-species jump between vertebrate class hosts.
Highlights
The study of diseases in nonhuman primates is of acute interest, with recent heightened concern over the emergence of infectious zoonoses due to accelerated anthropogenically driven environmental changes (e.g., [1,2,3])
Given that the interaction between endogenous retroviruses (ERVs) and infecting exogenous retroviruses may play a role in pathogenesis, discovering existing ERVs in basal primates such as lemurs has implications for the evolution of host immune responses and for recombination events that may result in cross-species transmissions, between closely related hosts, and even across vertebrate classes [21,23,24]
Primers were designed to the 5 long terminal repeat (LTR) using a forward primer annealing to the U3 region (5 -CTGCGGAAGAGCTTGTAAGTTTC-3 ), and the reverse primer to Gag (5 -CCAGTACGCAAAGGCAGTCACTGGAAC-3 ), and to the 3 LTR sequences using forward primer annealing to Env (5 -CTCATCAATTAATCTCTGATGTCCAAGC-3 ), and the reverse primer to the U5 region (5 -CAAGAAATGGAGACAAGACAGGTCTC-3 )
Summary
The study of diseases in nonhuman primates is of acute interest, with recent heightened concern over the emergence of infectious zoonoses due to accelerated anthropogenically driven environmental changes (e.g., [1,2,3]). There are currently 99 extant lemur species that arose 62 million years ago and diverged into several groups [11,12,13] Like their hosts, conceivably some of the microbes of lemurs have been evolving in isolation from mainland Africa, making them unique evolutionary markers. Given that the interaction between ERVs and infecting exogenous retroviruses may play a role in pathogenesis, discovering existing ERVs in basal primates such as lemurs has implications for the evolution of host immune responses and for recombination events that may result in cross-species transmissions, between closely related hosts, and even across vertebrate classes [21,23,24]. We use molecular analyses to examine the coevolutionary history of this virus with its lemur host and discuss the conservation implications of ERVs in primates
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