EXPRESSION AND SPLICING OF THE LATENCY-ASSOCIATED TRANSCRIPTS OF HERPES-SIMPLEX VIRUS TYPE-1 IN NEURONAL AND NONNEURONAL CELL-LINES

Herpes simplex virus type 1 (HSV-1) is transcriptionally active during latent infection in human peripheral sensory ganglia. This transcript ion has been linked to the ability of the virus to reactivate, but its potential gene products and mechanisms of action are unknown. To anal yze the viral latency-related transcripts in neuronal and non-neuronal cell lines in an isolated cellular system, a 10.4 kb DNA fragment, wh ich covers the entire viral transcriptionally active latency-associate d region, was cloned under control of the constitutive cytomegalovirus promoter (pNM3). During transient transfection of a human embryonic k idney 293 cell line, pNM3 expressed high levels of the 2.0 kb latency- associated transcript (LAT) that was not polyadenylated. The 1.5 kb LA T as well as the minor hybridizing RNAs could not be identified by Nor thern blotting analysis. pNM3 expression was further analyzed followin g transfection of two neuronal, C1300 and ND7 cell lines. The 2.0 kb L AT was synthesized at high levels in these cell lines. The 1.5 kb LAT, which in vivo can be identified only during HSV-1 latent infection in tissues which facilitate reactivation, was present at very low amount s in 293 and C1300 cells using reverse transcription PCR analysis. Hig her amounts of the 1.5 kb LAT were produced in ND7 cells, a neuronal c ell line shown to possess neuronal-specific splicing proteins. However , the 1.5 kb LAT was present in ND7 cells in lesser amounts than produ ced during latent infection in peripheral sensory ganglia. This novel cellular system provides now a tool for future studies of the role of the 1.5 kb and the 2.0 kb LATs in HSV-1 latency.