Expression kinetics of the transcript and product of the UL28 homologue ofbovine herpesvirus 1

We report that the bovine herpesvirus 1 (BHV1) UL28 ORF, a homologue of the herpes simplex virus (HSV) UL28 gene, represents a functional gene encodin g a viral specific protein. The BHV1 UL28 ORF, located at positions 53 058 --> 55 538 of the viral genome. encodes a viral specific transcript of 3.4 kb detected at 6 h post-infection (p.i.) after which its levels accumulated up to 12 h p.i. and then remained constant up to 24 h p.i. Transcription o f the BHV1 UL28 was determined to initiate 95 bases upstream from the ORF's initiating codon, which corresponds to 33 nucleotides downstream from a pu tative TATA box. A BHV1 UL28 specific antiserum, generated against a T7-Tag /UL28 fusion protein expressed in E. coli, specifically reacted with a 100 kDa protein in Western blots of BHV1-infected protein cell lysates. The exp ression kinetics of the protein was delayed by 6 h relative to that of its transcript suggesting that the gene is regulated at the translational level . In contrast to the HSV and pseudorabies virus UL28 genes, which belong to viral genes of the early (beta) class, that of BHV1 was unambiguously clas sified as a gamma2 gene. Further studies will be required to determine whet her these kinetic differences have any functional implications. (C) 2001 El sevier Science B.V. All rights reserved.