Analysis of the nucleotide sequence of five genes at the left end of the unique short region of the equine herpesvirus 4 genome.

Eco RI fragment G of equine herpesvirus 4 strain 405/76 (EHV 4.405/76) is located at the left end of the unique short region close to or extending into the internal repeat region of the prototypic arrangement of the genome. The nucleotide sequence of two subclones designated HS and G 19, contiguous within Eco RI fragment G, was determined for each strand by obtaining a nested set of deletion clones of these double-stranded DNA plasmids. Analysis of the nucleotide sequence revealed that the two subclones contain 5449 base pairs with four complete open reading frames (ORFs) and part of a fifth ORF. Comparison of the predicted amino acid sequences of these reading frames showed that they correspond to ORFs 67, 68, 69, 70, and 71 of equine herpesvirus type 1 (EHV 1) [41], of which ORFs 68, 69, and 70 are homologous to human herpes simplex virus (HSV) genes in the unique short (US) region, i.e., US 2, US 3, and US 4. ORF 67' of EHV 4 and ORF 67 of EHV 1 are homologous (65.7%) but these genes have no homologue in HSV 1.