Comprehensive phylogenomic analysis reveals a novel cluster of simian endogenous retroviral sequences in Colobinae monkeys.

Simian retrovirus (SRV) is a type-D betaretrovirus infectious to the Old World monkeys causing a variety of symptoms. SRVs are also present in the Old World monkey genomes as endogenous forms, which are referred to as Simian endogenous retroviruses (SERVs). Although many SERV sequences have been identified in Cercopithecinae genomes, with potential of encoding all functional genes, the distribution of SERVs in genomes and evolutionary relationship between exogeneous SRVs and SERVs remains unclear. In this study, we comprehensively investigated seven draft genome sequences of the Old World monkeys, and identified a novel cluster of SERVs in the two Rhinopithecus (R. roxellana and R. bieti) genomes, which belong to the Colobinae subfamily. The Rhinopithecus genomes harbored higher copy numbers of SERVs than the Cercopithecinae genomes. A reconstructed phylogenetic tree showed that the Colobinae SERVs formed a distinct cluster from SRVs and Cercopithecinae SERVs, and more closely related to exogenous SRVs than Cercopithecinae SERVs. Three radical amino acid substitutions specific to Cercopithecinae SERVs, which potentially affect the infectious ability of SERVs, were also identified in the proviral envelope protein. In addition, we found many integration events of SERVs were genus- or species-specific, suggesting the recent activity of SERVs in the Old World monkey genomes. The results suggest that SERVs in Cercopithecinae and Colobinae monkeys were endogenized after the divergence of subfamilies and do not transmit across subfamilies. Our findings also support the hypothesis that Colobinae SERVs are direct ancestors of SRV-6, which has a different origin from the other exogenous SRVs. These findings shed novel insight into the evolutionary history of SERVs, and may help to understand the process of endogenization of SRVs.

Isolation and characterization of adenoviruses infecting endangered golden snub-nosed monkeys (Rhinopithecus roxellana).

BACKGROUND: Adenoviruses are important pathogens with the potential for interspecies transmission between humans and non-human primates. Although many adenoviruses have been identified in monkeys, the knowledge of these viruses from the Colobinae members is quite limited. FINDINGS: We conducted a surveillance of viral infection in endangered golden snub-nosed monkeys (Rhinopithecus roxellana) in the subfamily Colobinae in China, and found that 5.1% of sampled individuals were positive for adenovirus. One of the adenoviruses (SAdV-WIV19) was successfully isolated and its full-length genome was sequenced. The full-length genome of WIV19 is 33,562 bp in size, has a G + C content of 56.2%, and encodes 35 putative genes. Sequence analysis revealed that this virus represents a novel species in the genus Mastadenovirus. Diverse cell lines, including those of human origin, were susceptible to WIV19. CONCLUSION: We report the first time the isolation and full-length genomic characterization of an adenovirus from the subfamily Colobinae.