A Herpes Simplex Virus Type 1 Mutant Expressing a Baculovirus Inhibitor of Apoptosis Gene in Place of Latency-Associated Transcript Has a Wild-Type Reactivation Phenotype in the Mouse

Authors

Ling Jin, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Guey-Chuen Perng, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Kevin R. Mott, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Nelson Osorio, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Julie Naito, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
David J. Brick, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Dale Carpenter, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California
Clinton J. Jones, University of Nebraska - LincolnFollow
Steven L. Wechsler, Department of Ophthalmology, University of California Irvine, School of Medicine, Irvine, California

Date of this Version

October 2005

Comments

Published in JOURNAL OF VIROLOGY, Oct. 2005, p. 12286–12295 Vol. 79, No. 19. Copyright © 2005, American Society for Microbiology. Used by permission.

Abstract

The latency-associated transcript (LAT) is essential for the wild-type herpes simplex virus type 1 (HSV-1) high-reactivation phenotype since LAT^- mutants have a low-reactivation phenotype. We previously reported that LAT can decrease apoptosis and proposed that this activity is involved in LAT’s ability to enhance the HSV-1 reactivation phenotype. The first 20% of the primary 8.3-kb LAT transcript is sufficient for enhancing the reactivation phenotype and for decreasing apoptosis, supporting this proposal. For this study, we constructed an HSV-1 LAT^- mutant that expresses the baculovirus antiapoptosis gene product cpIAP under control of the LAT promoter and in place of the LAT region mentioned above. Mice were ocularly infected with this mutant, designated dLAT-cpIAP, and the reactivation phenotype was determined using the trigeminal ganglion explant model. dLAT-cpIAP had a reactivation phenotype similar to that of wild-type virus and significantly higher than that of (i) the LAT^- mutant dLAT2903; (ii) dLAT1.5, a control virus containing the same LAT deletion as dLAT-cpIAP, but with no insertion of foreign DNA, thereby controlling for potential readthrough transcription past the cpIAP insert; and (iii) dLAT-EGFP, a control virus identical to dLATcpIAP except that it contained the enhanced green fluorescent protein open reading frame (ORF) in place of the cpIAP ORF, thereby controlling for expression of a random foreign gene instead of the cpIAP gene. These results show that an antiapoptosis gene with no sequence similarity to LAT can efficiently substitute for the LAT function involved in enhancing the in vitro-induced HSV-1 reactivation phenotype in the mouse.