Identification of the pseudorabies virus UL4 and UL5 (helicase) genes.

The DNA sequence of the left end of the pseudorabies virus (PRV) BamHI-G fragment and a short adjacent sequence from the BamHI-C fragment (0.641-0.664 map units) were determined. Two open reading frames were identified and designated PRV UL4 and UL5 because they exhibit amino acid sequence homology to the herpes simplex virus type 1 UL4 and UL5 open reading frames. The PRV UL4 open reading frame codes for a 145-amino acid polypeptide of unknown function. The deduced PRV UL5 gene product is 833 amino acid residues and exhibits sequence characteristics of a helicase, including six sequence motifs which are conserved for a superfamily of helicases. PRV UL5 also contains a putative leucine zipper motif which is not present in other herpesvirus helicase sequences. PRV UL4 and UL5 are transcribed in the opposite orientation with respect to the UL1, UL2, UL3, and UL3.5 gene cluster located at the right end of BamHI-G.