title: Herpes simplex virus 1 ICP0 phosphorylation site mutants are attenuated for viral replication and impaired for explant-induced reactivation.
abstract: In cell culture experiments, phosphorylation appears to be a critical regulator of the herpes simplex virus 1 (HSV-1) immediate-early (IE) protein, ICP0, which is an E3 ubiquitin ligase that transactivates viral gene expression. Three major regions of phosphorylation in ICP0 (amino acids 224 to 232, 365 to 371, and 508 to 518) have been identified, and mutant viruses that block phosphorylation sites within each region (termed Phos 1, 2, and 3, respectively) have been constructed. Previous studies indicated that replication of Phos 1 is significantly reduced compared to that of wild-type virus in cell culture (C. Boutell, et al., J. Virol. 82:10647-10656, 2008). To determine the effects these phosphorylation site mutations have on the viral life cycle in vivo, mice were ocularly infected with wild-type HSV-1, the Phos mutants, or their marker rescue counterparts. Subsequently, viral replication, establishment of latency, and viral explant-induced reactivation of these viruses were examined. Relative to wild-type virus, Phos 1 eye titers were reduced as much as 7- and 18-fold on days 1 and 5 postinfection, respectively. Phos 2 eye titers showed a decrease of 6-fold on day 1 postinfection. Titers of Phos 1 and 2 trigeminal ganglia were reduced as much as 16- and 20-fold, respectively, on day 5 postinfection. Additionally, the reactivation efficiencies of Phos 1 and 2 were impaired relative to wild-type HSV-1, although both viruses established wild-type levels of latency in vivo. The acute replication, latency, and reactivation phenotypes of Phos 3 were similar to those of wild-type HSV-1. We conclude from these studies that phosphorylation is likely a key modulator of ICP0's biological activities in a mouse ocular model of HSV-1 infection.
authors.affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
authors.forename: Heba H
authors.initials: HH
authors.lastname: Mostafa
authors.forename: Thornton W
authors.initials: TW
authors.lastname: Thompson
authors.forename: Anna S
authors.initials: AS
authors.lastname: Kushnir
authors.forename: Steve D
authors.initials: SD
authors.lastname: Haenchen
authors.forename: Adam M
authors.initials: AM
authors.lastname: Bayless
authors.forename: Joshua G
authors.initials: JG
authors.lastname: Hilliard
authors.forename: Malen A
authors.initials: MA
authors.lastname: Link
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Pitcher
authors.forename: Emma
authors.initials: E
authors.lastname: Loveday
authors.forename: Priscilla A
authors.initials: PA
authors.lastname: Schaffer
authors.forename: David J
authors.initials: DJ
authors.lastname: Davido
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002522:Chlorocebus aethiops; D005128:Eye Diseases / Q000378:metabolism / Q000821:virology*; D005260:Female; D016679:Genome, Viral; D006561:Herpes Simplex / Q000378:metabolism / Q000821:virology*; D018259:Herpesvirus 1, Human / Q000472:pathogenicity*; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D012668:Trigeminal Ganglion / Q000378:metabolism / Q000821:virology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism; D014709:Vero Cells; D014775:Virus Activation; D017735:Virus Latency; D014779:Virus Replication
chemical_list: D017874:Immediate-Early Proteins; D044767:Ubiquitin-Protein Ligases; C051804:Vmw110 protein, Human herpesvirus 1