title: In vivo replication of an ICP34.5 second-site suppressor mutant following corneal infection correlates with in vitro regulation of eIF2 alpha phosphorylation.
abstract: In animal models of herpes simplex virus type 1 (HSV-1) infection, ICP34.5-null viruses are avirulent and also fail to grow in a variety of cultured cells due to their inability to prevent RNA-dependent protein kinase (PKR)-mediated inhibition of protein synthesis. We show here that the inability of ICP34.5 mutants to grow in vitro is due specifically to the accumulation of phosphorylated eIF2 alpha. Mutations suppressing the in vitro phenotype of ICP34.5-null mutants have been described which map to the unique short region of the HSV-1 genome, resulting in dysregulated expression of the US11 gene. Despite the inability of the suppressor mutation to suppress the avirulent phenotype of the ICP34.5-null parental virus following intracranial inoculation, the suppressor mutation enhanced virus growth in the cornea, trigeminal ganglia, and periocular skin following corneal infection compared to that with the ICP34.5-null virus. The phosphorylation state of eIF2 alpha following in vitro infection with the suppressor virus was examined to determine if in vivo differences could be attributed to differential regulation of eIF2 alpha phosphorylation. The suppressor virus prevented accumulation of phosphorylated eIF2 alpha, while the wild-type virus substantially reduced eIF2 alpha phosphorylation levels. These data suggest that US11 functions as a PKR antagonist in vivo, although its activity may be modulated by tissue-specific differences in translation regulation.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Ward
authors.forename: Donalyn
authors.initials: D
authors.lastname: Scheuner
authors.forename: Jeremy
authors.initials: J
authors.lastname: Poppers
authors.forename: Randal J
authors.initials: RJ
authors.lastname: Kaufman
authors.forename: Ian
authors.initials: I
authors.lastname: Mohr
authors.forename: David A
authors.initials: DA
authors.lastname: Leib
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003316:Corneal Diseases / Q000821:virology; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D016849:Keratitis, Herpetic / Q000821:virology*; D051379:Mice; D010766:Phosphorylation; D013489:Suppression, Genetic; D014764:Viral Proteins / Q000235:genetics*; D014774:Virulence; D014779:Virus Replication
chemical_list: D015852:Eukaryotic Initiation Factor-2; D014764:Viral Proteins; C066469:gamma 34.5 protein, Human herpesvirus 1