EXPRESSION OF A HERPES-SIMPLEX VIRUS 1 OPEN READING FRAME ANTISENSE TO THE GAMMA(1)34.5 GENE AND TRANSCRIBED BY AN RNA 3' COTERMINAL WITH THE UNSPLICED LATENCY-ASSOCIATED TRANSCRIPT

Sensory neurons harboring latent herpes simplex virus 1 express viral RNAs derived from one or more transcriptional units contained in the i nverted repeats which flank the long unique sequence but which termina te in the inverted repeats flanking the small unique sequences of vira l DNA. These transcripts are also made in productively infected cells. We have identified 16 potential open reading frames (ORFs) predicted to encode 50 or more codons within the domain of the largest reported unspliced transcript and examined 5 ORFs by in-frame insertion of a se quence encoding an epitope reacting with a monoclonal antibody against a human cytomegalovirus protein. One ORF (ORF P), coincident with but antisense to the gamma(1)34.5 gene, was expressed but only under cond itions in which ICP4 was not functional. To ensure the authenticity of the expression, a second degenerate sequence encoding the same epitop e was inserted into a distant site of the same ORF. The protein expres sed by the ORF P with two insertions migrated more slowly than the one carrying one insertion only, indicating that ORF P is expressed.