Abstract The 130-kDa bovine herpesvirus-1 (BHV-1) glycoprotein GVP 6 was found to cross-react immunologically with the herpes simplex glycoprotein gB. Antibodies in polyclonal serum against gB immunoprecipitated GVP 6 and its cleavage products from a lysate of BHV-1-infected cells. Conversely, polyclonal serum against GVP 6 precipitated gB from HSV1-infected cell lysates. Sera against the other glycoproteins did not demonstrate cross-reactivity. A 3.6-kb Kpnl-Hpal fragment of BHV-1 DNA that hybridized to the gene for gB was cloned and the nucleotide sequence of both strands was determined. The longest codon reading frame in the fragment coded for a protein that showed extensive homology with gB1 and related sequences from pseudorabies virus, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus. The strongest homologies were observed in two segments of the ectodomain, the transmembrane domain, and sequences adjacent to the transmembrane domain.