title: MicroRNAs expressed by herpes simplex virus 1 during latent infection regulate viral mRNAs.
abstract: Herpesviruses are characterized by their ability to maintain life-long latent infections in their animal hosts. However, the mechanisms that allow establishment and maintenance of the latent state remain poorly understood. Herpes simplex virus 1 (HSV-1) establishes latency in neurons of sensory ganglia, where the only abundant viral gene product is a non-coding RNA, the latency associated transcript (LAT). Here we show that LAT functions as a primary microRNA (miRNA) precursor that encodes four distinct miRNAs in HSV-1 infected cells. One of these miRNAs, miR-H2-3p, is transcribed in an antisense orientation to ICP0-a viral immediate-early transcriptional activator that is important for productive HSV-1 replication and thought to have a role in reactivation from latency. We show that miR-H2-3p is able to reduce ICP0 protein expression, but does not significantly affect ICP0 messenger RNA levels. We also identified a fifth HSV-1 miRNA in latently infected trigeminal ganglia, miR-H6, which derives from a previously unknown transcript distinct from LAT. miR-H6 shows extended seed complementarity to the mRNA encoding a second HSV-1 transcription factor, ICP4, and inhibits expression of ICP4, which is required for expression of most HSV-1 genes during productive infection. These results may explain the reported ability of LAT to promote latency. Thus, HSV-1 expresses at least two primary miRNA precursors in latently infected neurons that may facilitate the establishment and maintenance of viral latency by post-transcriptionally regulating viral gene expression.
authors.affiliation: Department of Molecular Genetics and Microbiology and Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Jennifer Lin
authors.initials: JL
authors.lastname: Umbach
authors.forename: Martha F
authors.initials: MF
authors.lastname: Kramer
authors.forename: Igor
authors.initials: I
authors.lastname: Jurak
authors.forename: Heather W
authors.initials: HW
authors.lastname: Karnowski
authors.forename: Donald M
authors.initials: DM
authors.lastname: Coen
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Cullen
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015536:Down-Regulation; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics; D017735:Virus Latency / Q000235:genetics* / Q000502:physiology
chemical_list: D017874:Immediate-Early Proteins; D035683:MicroRNAs; D012333:RNA, Messenger; D012367:RNA, Viral; C048925:herpes simplex virus, type 1 protein ICP4; C477253:latency associated transcript, herpes simplex virus-1; D044767:Ubiquitin-Protein Ligases; C051804:Vmw110 protein, Human herpesvirus 1