title: RNA splicing in a new rhabdovirus from Culex mosquitoes.
abstract: Among members of the order Mononegavirales, RNA splicing events have been found only in the family Bornaviridae. Here, we report that a new rhabdovirus isolated from the mosquito Culex tritaeniorhynchus replicates in the nuclei of infected cells and requires RNA splicing for viral mRNA maturation. The virus, designated Culex tritaeniorhynchus rhabdovirus (CTRV), shares a similar genome organization with other rhabdoviruses, except for the presence of a putative intron in the coding region for the L protein. Molecular phylogenetic studies indicated that CTRV belongs to the family Rhabdoviridae, but it is yet to be assigned a genus. Electron microscopic analysis revealed that the CTRV virion is extremely elongated, unlike virions of rhabdoviruses, which are generally bullet shaped. Northern hybridization confirmed that a large transcript (approximately 6,500 nucleotides [nt]) from the CTRV L gene was present in the infected cells. Strand-specific reverse transcription-PCR (RT-PCR) analyses identified the intron-exon boundaries and the 76-nt intron sequence, which contains the typical motif for eukaryotic spliceosomal intron-splice donor/acceptor sites (GU-AG), a predicted branch point, and a polypyrimidine tract. In situ hybridization exhibited that viral RNAs are primarily localized in the nucleus of infected cells, indicating that CTRV replicates in the nucleus and is allowed to utilize the host's nuclear splicing machinery. This is the first report of RNA splicing among the members of the family Rhabdoviridae.
authors.affiliation: Department of Medical Entomology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
authors.forename: Ryusei
authors.initials: R
authors.lastname: Kuwata
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Isawa
authors.forename: Keita
authors.initials: K
authors.lastname: Hoshino
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Tsuda
authors.forename: Tohru
authors.initials: T
authors.lastname: Yanase
authors.forename: Toshinori
authors.initials: T
authors.lastname: Sasaki
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kyoko
authors.initials: K
authors.lastname: Sawabe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D003465:Culex / Q000821:virology*; D016679:Genome, Viral / Q000235:genetics; D007438:Introns; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012209:Rhabdoviridae / Q000145:classification / Q000235:genetics* / Q000648:ultrastructure; D017422:Sequence Analysis, DNA; D014764:Viral Proteins / Q000235:genetics; D014779:Virus Replication
chemical_list: D012333:RNA, Messenger; D012367:RNA, Viral; D014764:Viral Proteins