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.
Index: Endogenous retrovirus, Gamma-type betaretrovirus, PSRV1, Propithecus coquereli