RESUMEN
Lemurs are highly endangered mammals inhabiting the forests of Madagascar. In this study, we performed virus discovery on serum samples collected from 84 wild lemurs and identified viral sequence fragments from 4 novel viruses within the family Flaviviridae, including members of the genera Hepacivirus and Pegivirus. The sifaka hepacivirus (SifHV, two genotypes) and pegivirus (SifPgV, two genotypes) were discovered in the diademed sifaka (Propithecus diadema), while other pegiviral fragments were detected in samples from the indri (Indri indri, IndPgV) and the weasel sportive lemur (Lepilemur mustelinus, LepPgV). Although data are preliminary, each viral species appeared host species-specific and frequent infection was detected (18 of 84 individuals were positive for at least one virus). The complete coding sequence and partial 5' and 3' untranslated regions (UTRs) were obtained for SifHV and its genomic organization was consistent with that of other hepaciviruses, with one unique polyprotein and highly structured UTRs. Phylogenetic analyses showed the SifHV belonged to a clade that includes several viral species identified in rodents from Asia and North America, while SifPgV and IndPgV were more closely related to pegiviral species A and C, that include viruses found in humans as well as New- and Old-World monkeys. Our results support the current proposed model of virus-host co-divergence with frequent occurrence of cross-species transmission for these genera and highlight how the discovery of more members of the Flaviviridae can help clarify the ecology and evolutionary history of these viruses. Furthermore, this knowledge is important for conservation and captive management of lemurs.
Asunto(s)
Infecciones por Flaviviridae/veterinaria , Flaviviridae/aislamiento & purificación , Lemur/virología , Enfermedades de los Primates/virología , Animales , Flaviviridae/clasificación , Flaviviridae/genética , Flaviviridae/fisiología , Infecciones por Flaviviridae/virología , Variación Genética , Madagascar , FilogeniaRESUMEN
Lentiviruses are widespread in a variety of vertebrates, often associated with chronic disease states. However, until the recent discovery of the prehistoric endogenous lentiviruses in rabbits (RELIK) and lemurs (PSIV), it was thought that lentiviruses had no capacity for germline integration and were only spread horizontally in an exogenous fashion. The existence of RELIK and PSIV refuted these ideas, revealing lentiviruses to be present in a range of mammals, capable of germline integration, and far more ancient than previously thought. Using Gag sequences reconstructed from the remnants of these prehistoric lentiviruses, we have produced chimeric lentiviruses capable of infecting nondividing cells and determined structures of capsid domains from PSIV and RELIK. We show that the structures from these diverse viruses are highly similar, containing features found in modern-day lentiviruses, including a functional cyclophilin-binding loop. Together, these data provide evidence for an ancient capsid-cyclophilin interaction preserved throughout lentiviral evolution.
Asunto(s)
Proteínas de la Cápside/química , Ciclofilina A/metabolismo , Retrovirus Endógenos/química , Retrovirus Endógenos/genética , Evolución Molecular , Lentivirus/química , Lentivirus/genética , Animales , Secuencia de Bases , Cápside/metabolismo , Proteínas de la Cápside/genética , Proteínas de la Cápside/metabolismo , Cristalografía por Rayos X , Ciclofilina A/química , Metilación de ADN , Retrovirus Endógenos/fisiología , Productos del Gen gag/química , Productos del Gen gag/metabolismo , Genes Virales , Genes gag , Lemur/virología , Lentivirus/fisiología , Lentivirus de los Primates/química , Lentivirus de los Primates/genética , Lentivirus de los Primates/fisiología , Modelos Moleculares , Estructura Terciaria de Proteína , Conejos , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Virión/metabolismoRESUMEN
The coding capacity for retroviral Gag and Env proteins has been maintained in human endogenous retroviruses of the HERV-K family. HERV-K homologous sequences have been found in all Old World primates. Here, we examined Old World primate species for the presence of full-length HERV-K gag and env genes and the presence of gag and env open reading frames as determined by the protein truncation test. Full-length HERV-K env genes were found in DNAs of all Old World primate species, whereas open reading frames for Env protein were found solely in human, chimpanzee, and gorilla DNAs. The mutational event leading to two HERV-K types was found to have occurred after the separation of hominids from lower Old World primates and before the expansion of hominids. Full-length HERV-K gag genes in hominids displayed a 96-bp deletion compared to those in lower Old World primates. The ancient gag variant has not been maintained during hominid evolution. Open reading frames for HERV-K Gag have been found in all Old World primates except chimpanzees. Our study of the HERV-K family during Old World primate evolution contributes to the understanding of their possible biological functions in the host genomes.