Mapping herpes simplex virus type 1 latency-associated transcript sequences that protect from apoptosis mediated by a plasmid expressing caspase-8.

LAT (latency-associated transcript) is the only herpes simplex virus type 1 (HSV-1) transcript abundantly expressed during neuronal latency. LAT expression is required for the high reactivation phenotype of HSV-1 and this phenotype correlates with LAT's anti-apoptosis properties. LAT nucleotides 1 to 1499 inhibit caspase-8 (death receptor apoptotic pathway), but not caspase-9 (mitochondrial apoptotic pathway), -induced apoptosis as efficiently as larger LAT fragments. LAT sequences important for inhibiting caspase-8-induced apoptosis were also localized. The ability of LAT nucleotides 1 to 1499 to efficiently inhibit caspase-8-induced apoptosis correlates with the high reactivation phenotype of a mutant virus expressing just the first 1.5 kb of LAT (nucleotides 1 to 1499).