The bovine herpesvirus-1 LR ORF2 is critical for this gene's ability to restore the high wild-type reactivation phenotype to a herpes simplex virus-1 LAT null mutant.
During neuronal latency of herpes simplex virus (HSV)-1, the latency-associated transcript (LAT) is the only viral gene readily detectable. LAT is required for the high-level reactivation phenotype in animal models. LAT's anti-apoptotic activity was recently demonstrated by our group and it was proposed that LAT's anti-apoptotic function is involved in enhancing the reactivation phenotype. Recently, using chimeric virus CJLAT, it was shown that the reactivation phenotype of LAT(-) mutant dLAT2903 can be restored to wild-type levels by inserting the bovine herpes virus (BHV)-1 latency-related (LR) gene into the LAT locus of this HSV-1 LAT deletion mutant. Although transcription of the LR gene, like LAT, inhibits apoptosis, LR appears to be multifunctional. To investigate whether the LR gene's anti-apoptotic function was responsible for restoring the high-reactivation phenotype, a mutated BHV-1 LR gene was inserted into the LAT locus of HSV-1 generating the chimeric virus CJLATmut. This mutation consists of three stop codons inserted just after the ATG of the first LR open reading frame (ORF2). In plasmids and in a BHV-1 mutant, this mutation eliminated the LR gene's anti-apoptotic activity, strongly suggesting that ORF2 encodes a protein responsible for LR's anti-apoptotic activity. Reactivation of the CJLATmut virus, in both rabbits and mice, was significantly lower than in wild-type McKrae virus (P=0.0001 and P=0.0003, respectively) and CJLAT virus, containing wild-type LR in place of LAT (P<0.0001) and was similar to LAT(-) dLAT2903 (P=0.8 and P=0.7, respectively). Thus, disruption of BHV-1 LR ORF2 eliminated the high-reactivation phenotype.
Mott
Kevin R
KR
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Osorio
Nelson
N
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Jin
Ling
L
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Brick
David J
DJ
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Naito
Julie
J
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Cooper
Jennifer
J
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Henderson
Gail
G
Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583-0905, USA.
Inman
Melissa
M
Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583-0905, USA.
Jones
Clinton
C
Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583-0905, USA.
Wechsler
Steven L
SL
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
Perng
Guey-Chuen
GC
Department of Ophthalmology, University of California Irvine, UCIMC, 101 The City Drive, Orange, CA 92868-4380-02, USA.
D000818:Animals; D017209:Apoptosis; D036022:Capsid Proteins / Q000235:genetics*; D006023:Glycoproteins / Q000235:genetics*; D007242:Herpesvirus 1, Bovine / Q000235:genetics / Q000502:physiology*; D018259:Herpesvirus 1, Human / Q000235:genetics*; D051379:Mice; D009154:Mutation; D016366:Open Reading Frames; D010641:Phenotype; D011817:Rabbits; D014775:Virus Activation; D017735:Virus Latency / Q000235:genetics*; D014779:Virus Replication
D036022:Capsid Proteins; D006023:Glycoproteins