Herpes simplex virus 1 mutant with point mutations in UL39 is impaired for acute viral replication in mice, establishment of latency, and explant-induced reactivation

Heba H. Mostafa, Thornton W. Thompson, Adam J. Konen, Steve D. Haenchen, Joshua G. Hilliard, Stuart J. Macdonald, Lynda A. Morrison, David J. Davido

Research output: Contribution to journalArticlepeer-review

Abstract

In the process of generating herpes simplex virus 1 (HSV-1) mutations in the viral regulatory gene encoding infected cell protein 0 (ICP0), we isolated a viral mutant, termed KOS-NA, that was severely impaired for acute replication in the eyes and trigeminal ganglia (TG) of mice, defective in establishing a latent infection, and reactivated poorly from explanted TG. To identify the secondary mutation(s) responsible for the impaired phenotypes of this mutant, we sequenced the KOS-NA genome and noted that it contained two nonsynonymous mutations in UL39, which encodes the large subunit of ribonucleotide reductase, ICP6. These mutations resulted in lysine-to-proline (residue 393) and arginine-to-histidine (residue 950) substitutions in ICP6. To determine whether alteration of these amino acids was responsible for the KOS-NA phenotypes in vivo, we recombined the wild-type UL39 gene into the KOS-NA genome and rescued its acute replication phenotypes in mice. To further establish the role of UL39 in KOS-NA's decreased pathogenicity, the UL39 mutations were recombined into HSV-1 (generating UL39mut), and this mutant virus showed reduced ocular and TG replication in mice comparable to that of KOS-NA. Interestingly, ICP6 protein levels were reduced in KOS-NA-infected cells relative to the wild-type protein. Moreover, we observed that KOS-NA does not counteract caspase 8-induced apoptosis, unlike wild-type strain KOS. Based on alignment studies with other HSV-1 ICP6 homologs, our data suggest that amino acid 950 of ICP6 likely plays an important role in ICP6 accumulation and inhibition of apoptosis, consequently impairing HSV-1 pathogenesis in a mouse model of HSV-1 infection.

Original languageEnglish (US)
Article numbere01654-17
JournalJournal of virology
Volume92
Issue number7
DOIs
StatePublished - Apr 1 2018
Externally publishedYes

Keywords

  • Antiapoptosis
  • HSV-1
  • ICP6
  • Pathogenesis
  • Ribonucleotide reductase
  • UL39
  • Viral mutant

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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