title: A gene capable of blocking apoptosis can substitute for the herpes simplex virus type 1 latency-associated transcript gene and restore wild-type reactivation levels.
abstract: After ocular herpes simplex virus type 1 (HSV-1) infection, the virus travels up axons and establishes a lifelong latent infection in neurons of the trigeminal ganglia. LAT (latency-associated transcript), the only known viral gene abundantly transcribed during HSV-1 neuronal latency, is required for high levels of reactivation. The LAT function responsible for this reactivation phenotype is not known. Recently, we showed that LAT can block programmed cell death (apoptosis) in neurons of the trigeminal ganglion in vivo and in tissue culture cells in vitro (G.-C. Perng et al., Science 287:1500-1503, 2000; M. Inman et al., J. Virol. 75:3636-3646, 2001). Consequently, we proposed that this antiapoptosis function may be a key to the mechanism by which LAT enhances reactivation. To study this further, we constructed a recombinant HSV-1 virus in which the HSV-1 LAT gene was replaced by an alternate antiapoptosis gene. We used the bovine herpes virus 1 (BHV-1) latency-related (LR) gene, which was previously shown to have antiapoptosis activity, for this purpose. The resulting chimeric virus, designated CJLAT, contains two complete copies of the BHV-1 LR gene (one in each viral long repeat) in place of the normal two copies of the HSV-1 LAT, on an otherwise wild-type HSV-1 strain McKrae genomic background. We report here that in both rabbits and mice reactivation of CJLAT was significantly greater than the LAT null mutant dLAT2903 (P < 0.0004 and P = 0.001, respectively) and was at least as efficient as wild-type McKrae. This strongly suggests that a BHV-1 LR gene function was able to efficiently substitute for an HSV-1 LAT gene function involved in reactivation. Although replication of CJLAT in rabbits and mice was similar to that of wild-type McKrae, CJLAT killed more mice during acute infection and caused more corneal scarring in latently infected rabbits. This suggested that the BHV-1 LR gene and the HSV-1 LAT gene are not functionally identical. However, LR and LAT both have antiapoptosis activity. These studies therefore strongly support the hypothesis that replacing LAT with an antiapoptosis gene restores the wild-type reactivation phenotype to a LAT null mutant of HSV-1 McKrae.
authors.affiliation: Ophthalmology Research Laboratories, Cedars-Sinai Medical Center Burns & Allen Research Institute, Los Angeles, California, USA.
authors.forename: Guey-Chuen
authors.initials: GC
authors.lastname: Perng
authors.forename: Barak
authors.initials: B
authors.lastname: Maguen
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Mott
authors.forename: Nelson
authors.initials: N
authors.lastname: Osorio
authors.forename: Susan M
authors.initials: SM
authors.lastname: Slanina
authors.forename: Ada
authors.initials: A
authors.lastname: Yukht
authors.forename: Homayon
authors.initials: H
authors.lastname: Ghiasi
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Nesburn
authors.forename: Melissa
authors.initials: M
authors.lastname: Inman
authors.forename: Gail
authors.initials: G
authors.lastname: Henderson
authors.forename: Clinton
authors.initials: C
authors.lastname: Jones
authors.forename: Steven L
authors.initials: SL
authors.lastname: Wechsler
mesh_terms: D000818:Animals; D017209:Apoptosis; D002417:Cattle; D020803:Encephalitis, Herpes Simplex / Q000401:mortality / Q000821:virology*; D005123:Eye / Q000821:virology; D015870:Gene Expression; D005814:Genes, Viral / Q000502:physiology*; D005818:Genetic Engineering; D016679:Genome, Viral; D007242:Herpesvirus 1, Bovine / Q000235:genetics*; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D006801:Humans; D016849:Keratitis, Herpetic / Q000821:virology*; D008297:Male; D051379:Mice; D012367:RNA, Viral; D011817:Rabbits; D012668:Trigeminal Ganglion / Q000473:pathology / Q000821:virology; D014764:Viral Proteins / Q000235:genetics*; D014775:Virus Activation; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; C401822:latency-related protein, Bovine herpesvirus 1