THE BAMHI FRAGMENT-9 OF PSEUDORABIES VIRUS CONTAINS GENES HOMOLOGOUS TO THE UL24, UL25, UL26, AND UL26.5 GENES OF HERPES-SIMPLEX VIRUS TYPE-1

The genomes of pseudorabies virus (PrV) and of herpes simplex virus ty pe 1 (HSV1) are colinear, excepting an inversion in the unique long re gion, of which one extremity resides within the BamHI fragment 9. This fragment (4088 bp) encodes the counterparts of HSV1 UL24, UL25, UL26 and UL26.5 that are transcribed into four 3'-coterminal mRNAs. Multipl e alignments of UL24, UL25 and UL26 protein homologs from alpha-, beta - and gamma-herpesviruses were performed. The PrV UL24 protein is shor ter than its counterparts, missing the non-conserved COOH-terminal reg ion. The region which is common to all viruses contains a basic NH2-te rminus and a hydrophobic COOH-end, suggesting that UL24 may function a s a matrix protein. The UL25 proteins are well conserved, particularly among the alpha-herpesviruses. All the domains involved in the proteo lytic activity of the UL26 protein are highly conserved, as well as th e two cleavage sites. Thus, its function and processing may be similar in PIV as in other herpesviruses. Due to the fact that in PrV the UL2 6 and UL44 genes are adjacent and their ends are conserved, the right border of the inversion must lie within their intergenic region.