RESUMO
Although segmented and unsegmented RNA viruses are commonplace, the evolutionary links between these two very different forms of genome organization are unclear. We report the discovery and characterization of a tick-borne virus--Jingmen tick virus (JMTV)--that reveals an unexpected connection between segmented and unsegmented RNA viruses. The JMTV genome comprises four segments, two of which are related to the nonstructural protein genes of the genus Flavivirus (family Flaviviridae), whereas the remaining segments are unique to this virus, have no known homologs, and contain a number of features indicative of structural protein genes. Remarkably, homology searching revealed that sequences related to JMTV were present in the cDNA library from Toxocara canis (dog roundworm; Nematoda), and that shared strong sequence and structural resemblances. Epidemiological studies showed that JMTV is distributed in tick populations across China, especially Rhipicephalus and Haemaphysalis spp., and experiences frequent host-switching and genomic reassortment. To our knowledge, JMTV is the first example of a segmented RNA virus with a genome derived in part from unsegmented viral ancestors.
Assuntos
Flaviviridae/genética , Genoma Viral , Carrapatos/virologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Bovinos , Linhagem Celular , China , DNA Viral/genética , Cães , Evolução Molecular , Flaviviridae/classificação , Flaviviridae/ultraestrutura , Flavivirus/genética , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Filogenia , Proteômica , Vírus Reordenados/classificação , Vírus Reordenados/genética , Vírus Reordenados/ultraestrutura , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Proteínas não Estruturais Virais/genéticaRESUMO
Surveys were carried out to better understand the tick vector ecology and genetic diversity of Huaiyangshan virus (HYSV) in both regions of endemicity and regions of nonendemicity. Haemaphysalis longicornis ticks were dominant in regions of endemicity, while Rhipicephalus microplus is more abundant in regions of nonendemicity. HYSV RNA was found in human and both tick species, with greater prevalence in H. longicornis and lesser prevalence in R. microplus. Phylogenetic analyses indicate that HYSV is a novel species of the genus Phlebovirus.