The latency-related gene of bovine herpesvirus 1 inhibits the activity of immediate-early transcription unit 1.

Bovine herpesvirus 1 (BHV-1) establishes a latent infection in sensory neurons of infected animals. Only one virus-encoded latency-related (LR) gene is expressed during a latent infection. The LR transcript overlaps immediate-early transcription unit 1 (IEtu1) and is anti-sense with respect to IEtu1. The transcriptional start site of the LR RNA was mapped to position 724 of the LR gene, downstream from two putative TATA elements. When LR promoter sequences were deleted from a plasmid containing IEtu1 and the LR gene, the resulting construct trans-activated the HSV-1 thymidine kinase (TK) promoter more efficiently than IEtu1 plus the LR gene. Cotransfection of a plasmid containing the intact LR gene with IEtu1 inhibited the ability of IEtu1 to trans-activate the TK promoter. These results imply that a LR gene product(s) repressed the trans-acting capacity of IEtu1.