Characterization of the latency-related transcriptionally active region of the bovine herpesvirus 1 genome.

Approximate 5' and 3' ends of the bovine herpesvirus 1 (BHV-1) latency-related RNA (LR RNA) were mapped in rabbit trigeminal ganglia (TG) by in situ hybridization. The data provide a size estimate of 0.77 to 1.16 kb for the LR RNA. An LR RNA mapping to a similar location was also detected in TG of cattle latently infected with BHV-1. The BHV-1 LR region is transcriptionally active in bovine cell cultures lytically infected with BHV-1. A 1.15-kb transcript, present at early and late times postinfection, of the same sense and approximate size that seen in latently infected TG overlaps a 2.9-kb immediate-early and a 2.6-kb early and late transcription unit present on the complementary strand. Sequence analysis of the LR RNA sense strand indicates the presence of a potential polymerase II promoter in close proximity to the 5' terminus of the LR RNA and two open reading frames within its map positions. The complementary strand contains the 3' portion of a large open reading frame that almost completely overlaps the map position of the LR RNA present on the opposite strand.