The virulence-determining genomic BamHI fragment 4 of pseudorabies virus contains genes corresponding to the U_L15 (partial), U_L18, U_L19, U_L20, and U_L21 genes of herpes-simplex virus and a putative origin of replication

The genomic BamHI-fragment 4 of pseudorabies virus (PrV) has previously been shown to encode functions necessary for expression of PrV neurovirulence (B. Lomniczi, S. Watanabe, T. Ben-Porat, and A. S. Kaplan, 1984, J. Virol. 52, 198–205). To identify proteins that might be involved in the neurotropism of PrV we sequenced the complete 9382-bp fragment BamHI-4, the longest contiguous sequence determined in the UL region of PrV so far, and analyzed its coding capacity. In an arrangement similar to that found in herpes simplex virus type 1 we identified complete open reading frames encoding proteins with strong homology to the UL18 (50% homology), UL19 (60% homology), UL20 (33% homology), and UL21 (36% homology) polypeptides and the 3′-part of a gene homologous to UL15 (67% homology) of HSV-1. In addition, a consensus sequence for an alphaherpesviral origin of replication was found at the left terminus of the fragment.