Characterization of an equine herpesvirus type 1 gene encoding a glycoprotein (gp13) with homology to herpes simplex virus glycoprotein C.
The molecular structure of the equine herpesvirus type 1 (EHV-1) gene encoding glycoprotein 13 (gp13) was analyzed. The gene is contained within a 1.8-kilobase AccI-EcoRI restriction fragment mapping at map coordinates 0.136 to 0.148 in the UL region of the EHV-1 genome and is transcribed from right to left. Determination of the nucleotide sequence of the DNA fragment revealed a complete transcriptional unit composed of typical regulatory promoter elements upstream to a long open reading frame (1,404 base pairs) that encoded a 468-amino-acid primary translation product of 51 kilodaltons. The predicted protein has the characteristic features of a membrane-spanning protein: an N-terminal signal sequence, a hydrophobic membrane anchor region, a charged C-terminal cytoplasmic tail, and an exterior domain with nine potential N-glycosylation sites. The EHV-1 DNA sequences expressed in lambda gt11 as gp13 epitopes were present in the open reading frame. Amino acid sequences composing a major antigenic site, recognized by 35% of a panel of 42 anti-gp13 monoclonal antibodies, were identified in the N-terminal surface domain of the deduced gp13 molecule. Comparison of the EHV-1 gp13 DNA sequence with that encoding glycoproteins of other alphaherpesviruses revealed no detectable homology. However, a search for homology at the amino acid level showed regions of significant sequence similarity between the amino acids of the carboxy half of EHV-1 gp13 and those of the same region of gC-like glycoproteins of herpes simplex virus (gC-1 and gC-2), pseudorabies herpesvirus (gIII), and varicella-zoster virus (gp66). The sequences of the N-terminal portion of gp13, by contrast, were much less conserved. The results of these studies indicate that EHV-1 gp13 is the structural homolog of herpes simplex virus glycoprotein C and further suggest that the epitope-containing N-terminal amino acid sequences of the herpesvirus gC-like glycoproteins have undergone more extensive evolutionary divergence than the C-terminal sequences.
Allen
G P
GP
Department of Veterinary Science, University of Kentucky, Lexington 40546-0099.
Coogle
L D
LD
D000595:Amino Acid Sequence; D000818:Animals; D000956:Antigens, Viral / Q000235:genetics; D001483:Base Sequence; D003062:Codon; D004279:DNA, Viral / Q000235:genetics; D000939:Epitopes; D005814:Genes, Viral; D006564:Herpesviridae / Q000235:genetics*; D006736:Horses / Q000382:microbiology; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012995:Solubility; D014759:Viral Envelope Proteins / Q000235:genetics*
D000956:Antigens, Viral; D003062:Codon; D004279:DNA, Viral; D000939:Epitopes; D014759:Viral Envelope Proteins