title: Role of immediate early protein ICP27 in the differential sensitivity of herpes simplex viruses 1 and 2 to leptomycin B.
abstract: Leptomycin B (LMB) is a highly specific inhibitor of CRM1, a cellular karyopherin-β that transports nuclear export signal-containing proteins from the nucleus to the cytoplasm. Previous work has shown that LMB blocks herpes simplex virus 1 (HSV-1) replication in Vero cells and that certain mutations in viral immediate early protein ICP27 can confer LMB resistance. However, little is known of the molecular mechanisms involved. Here we report that HSV-2, a close relative of HSV-1, is naturally resistant to LMB. To see whether the ICP27 gene determines this phenotypic difference, we generated an HSV-1 mutant that expresses the HSV-2 ICP27 instead of the HSV-1 protein. This recombinant was fully sensitive to LMB, indicating that one or more other viral genes must be important in determining HSV-2's LMB-resistant phenotype. In additional work, we report several findings that shed light on how HSV-1 ICP27 mutations can confer LMB resistance. First, we show that LMB treatment of HSV-1-infected cells leads to suppression of late viral protein synthesis and a block to progeny virion release. Second, we identify a novel type of ICP27 mutation that can confer LMB resistance, that being the addition of a 100-residue amino-terminal affinity purification tag. Third, by studying infections where both LMB-sensitive and LMB-resistant forms of ICP27 are present, we show that HSV-1's sensitivity to LMB is dominant to its resistance. Together, our results suggest a model in which the N-terminal portion of ICP27 mediates a nonessential activity that interferes with HSV-1 replication when CRM1 is inactive. We suggest that LMB resistance mutations weaken or abrogate this activity.
authors.affiliation: Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Donglim
authors.initials: D
authors.lastname: Park
authors.forename: Joy
authors.initials: J
authors.lastname: Lengyel
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Rice
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D024882:Drug Resistance, Viral; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D018259:Herpesvirus 1, Human / Q000187:drug effects*; D018258:Herpesvirus 2, Human / Q000187:drug effects*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D005231:Fatty Acids, Unsaturated; C057120:ICP27 protein, human herpesvirus 1; D017874:Immediate-Early Proteins; D050505:Mutant Proteins; C558833:UL54 protein, herpes simplex virus type II; D014764:Viral Proteins; C038753:leptomycin B