title: The HSV-1 Latency-Associated Transcript Functions to Repress Latent Phase Lytic Gene Expression and Suppress Virus Reactivation from Latently Infected Neurons.
abstract: Herpes simplex virus 1 (HSV-1) establishes life-long latent infection within sensory neurons, during which viral lytic gene expression is silenced. The only highly expressed viral gene product during latent infection is the latency-associated transcript (LAT), a non-protein coding RNA that has been strongly implicated in the epigenetic regulation of HSV-1 gene expression. We have investigated LAT-mediated control of latent gene expression using chromatin immunoprecipitation analyses and LAT-negative viruses engineered to express firefly luciferase or β-galactosidase from a heterologous lytic promoter. Whilst we were unable to determine a significant effect of LAT expression upon heterochromatin enrichment on latent HSV-1 genomes, we show that reporter gene expression from latent HSV-1 genomes occurs at a greater frequency in the absence of LAT. Furthermore, using luciferase reporter viruses we have observed that HSV-1 gene expression decreases during long-term latent infection, with a most marked effect during LAT-negative virus infection. Finally, using a fluorescent mouse model of infection to isolate and culture single latently infected neurons, we also show that reactivation occurs at a greater frequency from cultures harbouring LAT-negative HSV-1. Together, our data suggest that the HSV-1 LAT RNA represses HSV-1 gene expression in small populations of neurons within the mouse TG, a phenomenon that directly impacts upon the frequency of reactivation and the maintenance of the transcriptionally active latent reservoir.
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Nicoll
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Hann
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Maitreyi
authors.initials: M
authors.lastname: Shivkumar
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Laura E R
authors.initials: LE
authors.lastname: Harman
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Viv
authors.initials: V
authors.lastname: Connor
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Coleman
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: João T
authors.initials: JT
authors.lastname: Proença
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Stacey
authors.initials: S
authors.lastname: Efstathiou
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D044127:Epigenesis, Genetic / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D018259:Herpesvirus 1, Human / Q000235:genetics*; D009474:Neurons / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*; D017735:Virus Latency / Q000235:genetics*; D018406:Virus Physiological Phenomena / Q000235:genetics*
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins