Cellular FLIP can substitute for the herpes simplex virus type 1 latency-associated transcript gene to support a wild-type virus reactivation phenotype in mice.
Latency-associated transcript (LAT) deletion mutants of herpes simplex virus type 1 (HSV-1) have reduced reactivation phenotypes. Thus, LAT plays an essential role in the latency-reactivation cycle of HSV-1. We have shown that LAT has antiapoptosis activity and demonstrated that the chimeric virus, dLAT-cpIAP, resulting from replacing LAT with the baculovirus antiapoptosis gene cpIAP, has a wild-type HSV-1 reactivation phenotype in mice and rabbits. Thus, LAT can be replaced by an alternative antiapoptosis gene, confirming that LAT's antiapoptosis activity plays an important role in the mechanism by which LAT enhances the virus' reactivation phenotype. However, because cpIAP interferes with both of the major apoptosis pathways, these studies did not address whether LAT's proreactivation phenotype function was due to blocking the extrinsic (Fas-ligand-, caspase-8-, or caspase-10-dependent pathway) or the intrinsic (mitochondria-, caspase-9-dependent pathway) pathway, or whether both pathways must be blocked. Here we constructed an HSV-1 LAT(-) mutant that expresses cellular FLIP (cellular FLICE-like inhibitory protein) under control of the LAT promoter and in place of LAT nucleotides 76 to 1667. Mice were ocularly infected with this mutant, designated dLAT-FLIP, and the reactivation phenotype was determined using the trigeminal ganglia explant model. dLAT-FLIP had a reactivation phenotype similar to wild-type virus and significantly higher than the LAT(-) mutant dLAT2903. Thus, the LAT function responsible for enhancing the reactivation phenotype could be replaced with an antiapoptosis gene that primarily blocks the extrinsic signaling apoptosis pathway.
Jin
Ling
L
Department of Biomedical Sciences, Oregon State University Corvallis, Oregon, USA.
Carpenter
Dale
D
Moerdyk-Schauwecker
Megan
M
Vanarsdall
Adam L
AL
Osorio
Nelson
N
Hsiang
Chinhui
C
Jones
Clinton
C
Wechsler
Steven L
SL
D000818:Animals; D017209:Apoptosis; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D002460:Cell Line; D005123:Eye / Q000821:virology; D005260:Female; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral / Q000235:genetics; D006561:Herpes Simplex / Q000821:virology*; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology*; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D010641:Phenotype; D011817:Rabbits; D016019:Survival Analysis; D014775:Virus Activation / Q000235:genetics
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D035683:MicroRNAs; C477253:latency associated transcript, herpes simplex virus-1