Characterization of the glycoprotein B gene from ruminant alphaherpesviruses.

The complete open reading frame and promoter region of the glycoprotein B (gB) gene has been identified and sequenced from five poorly characterized alphaherpesviruses of ruminants, bovine herpesvirus 5 (BHV-5), buffalo herpesvirus 1 (BuHV-1), cervine herpesvirus 1 (CerHV-1), rangiferine herpesvirus 1 (RanHV-1), and caprine herpesvirus 1 (CapHV-1). One of the two regions identified with considerable sequence and length variation is also target of the immune system, as two B cell epitopes have been identified in this location. Features shared with bovine herpesvirus 1 (BHV-1) gB include two broad hydrophobic regions, six N-glycosylation sites and ten conserved cysteine residues in the gB extracellular domain. Phylogenetic analysis showed that the studied ruminant alphaherpesviruses form, together with BHV-1, a consistent group within the alpha2 subgroup of the herpesviruses. BHV-5 and BuHV-1 are most closely related to BHV-1, followed by CerHV-1, RanHV-1 and more distantly by CapHV-1. A remarkable high degree of sequence similarity was observed between BuHV-1 and the neuropathogenic BHV-5.