IDENTIFICATION AND CHARACTERIZATION OF THE BOVINE HERPESVIRUS-1 UL7 GENE AND GENE-PRODUCT WHICH ARE NOT ESSENTIAL FOR VIRUS-REPLICATION IN CELL-CULTURE

The UL7 gene of bovine herpesvirus 1 (BHV-1) strain Schonboken was fou nd at a position and in a context predicted from the gene order in the prototype alphaherpesvirus herpes simplex virus type 1. The gene and flanking regions were sequenced, the UL7 RNA and protein were characte rized, and 95.3% of the UL7 open reading frame was deleted from the vi ral genome without destroying productive virus replication. Concomitan t deletion of nine 3' codons from the BHV-1 UL6 ORF and 77 amino acids from the carboxy terminus of the predicted BHV-1 UL8 protein demonstr ated that these domains are also not essential for function of the res pective proteins. The UL7 open reading frame encodes a protein of 300 amino acids with a calculated molecular mass of 32 kDa. Comparison wit h UL7 homologs of other alphaherpesviruses revealed a high degree of h omology, the most prominent being to the predicted UL7 polypeptide of varicella-zoster virus, with 43.3% identical amino acids, A monospecif ic anti-UL7 serum identified the 33-kDa (apparent-molecular-mass) UL7 polypeptide which is translated from an early-expressed 1.7-kb RNA. Th e UL7 protein was localized in the cytoplasm of infected cells and cou ld not be detected in purified virions. In summary, we describe the fi rst identification of an alphaherpesviral UL7-encoded polypeptide and demonstrate that the UL7 protein is not essential for replication of B HV-1 in cell culture.