Characterization of the Genome of Equine Herpesvirus 1 Subtype 2

Abstract

SUMMARYThe genome structure of equine herpesvirus 1 (EHV-1) subtype 2 was shown by electron microscopic studies and restriction endonuclease site mapping to comprise two covalently linked segments (L, 109 kbp; S, 35 kbp). The S segment contains a unique sequence (Us) flanked by a substantial inverted repeat (TRs/IRs). Thus, the genome structure of EHV-1 subtype 2 is similar to that published previously for EHV-1 subtype 1, but the two subtypes differ in the occurrences of EcoRI and BamHI restriction sites. Hybridization studies using cloned EHV-1 DNA showed that the genome of EHV-1 subtype 2 is colinear with the genomes of EHV-1 subtype 1 and herpes simplex virus type 1. DNA sequence data for four EHV-1 subtype 2 genes, including one potentially encoding a glycoprotein, were obtained by sequencing a 4574 bp BamHI fragment containing the junction between Us and TRs. The genome structure, hybridization and sequence data confirm that EHV-1 subtype 2 is of the alphaherpesvirus lineage.

Equine Herpesvirus Type 1 Unique Short Fragment Encodes Glycoproteins with Homology to Herpes Simplex Virus Type 1 gD, gI and gE

“…§ The homology search was made against the EHV-4 gE carboxyterminal 255 amino acids since only this part of the protein is known (Cullinane et al, 1988).…”

“…Analysis of the predicted amino acid sequences of gpl3 and gpl4 glycoproteins revealed significant homology to the herpes simplex virus type 1 (HSV-1) gC and gB glycoproteins, respectively. Complete and partial nucleotide sequences have recently been described respectively for the EHV-4 gB glycoprotein (Riggio et al, 1989) and gE glycoprotein (Cullinane et al, 1988) genes.…”

The Nucleotide Sequence of an Equine Herpesvirus 4 Gene Homologue of the Herpes Simplex Virus 1 Glycoprotein H Gene

“…Of these genes, three (gpl4, gpl3 and gp17/18) map at positions collinear with the herpes simplex virus type 1 (HSV-1) gB, gC and gE genes and analysis of EHV-1 sequence data has identified gpl4 and gpl 3 as gB and gC homologues respectively (Whalley et al, 1989;Allen & Coogle, 1988). Analysis of EHV-4 sequence data has revealed the EHV-4 gB and gC gene homologues are similarly collinear with the HSV-1 genes and that agE homologue is encoded within the Us region of the genome (Riggio et al, 1989; (Cullinane et al, 1988). Subfragments of EHV-4 BamHI C, generated by restriction endonuclease digestion, were cloned into a Bluescript M 13 + vector (Stratagene) for sequence analysis.…”

The Nucleotide Sequence of the Equine Herpesvirus 4 Thymidine Kinase Gene

“…The EHV-4 genome is a dsDNA molecule of 144 kbp, composed of a long (L) and short component (S), the latter bounded by a set of inverted repeats (Cullinane et al, 1988). The EHV-4 TK gene was expected to map at around 0.5 map units (m.u.)…”

“…The EHV-4 TK gene was expected to map at around 0.5 map units (m.u.) given the reported position of the EHV-1 TK gene (Robertson & Whalley, 1988) and evidence for collinearity of the long components of the EHV-1 and EHV-4 genomes (Cullinane et al, 1988). Southern blot analyses were performed in which recombinant plasmids containing EHV-4 BamHI fragments mapping between 0.39 and 0.62 m.u.…”