title: Glycoprotein IV of bovine herpesvirus 1-expressing cell line complements and rescues a conditionally lethal viral mutant.
abstract: Glycoprotein IV (gIV) of bovine herpesvirus 1 (BHV-1), a homolog of herpes simplex virus glycoprotein D, represents a major component of the viral envelope and a dominant immunogen. To analyze the functional role of gIV during BHV-1 replication, cell line BUIV3-7, which constitutively expresses gIV, was constructed and used for the isolation of gIV- BHV-1 mutant 80-221, in which the gIV gene was replaced by a lacZ expression cassette. On complementing gIV-expressing cells, the gIV- BHV-1 replicated normally but was unable to form plaques and infectious progeny on noncomplementing cells. Further analysis showed that gIV is essential for BHV-1 entry into target cells, whereas viral gene expression, DNA replication, and envelopment appear unchanged in both noncomplementing and complementing cells infected with phenotypically complemented gIV- BHV-1. The block in entry could be overcome by polyethylene glycol-induced membrane fusion. After passaging of gIV- BHV-1 on complementing cells, a rescued variant, BHV-1res, was isolated and shown to underexpress gIV in comparison with its wild-type parent. Comparison of the penetration kinetics of BHV-1 wild type, phenotypically complemented gIV- BHV-1, and BHV-1res indicated that penetration efficiency correlated with the amount of gIV present in virus particles. In conclusion, we show that gIV of BHV-1 is an essential component of the virion involved in virus entry and that the amount of gIV in the viral envelope modulates the penetration efficiency of the virus.
authors.affiliation: Federal Research Center for Virus Diseases of Animals, Tübingen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Fehler
authors.forename: J M
authors.initials: JM
authors.lastname: Herrmann
authors.forename: A
authors.initials: A
authors.lastname: Saalmüller
authors.forename: T C
authors.initials: TC
authors.lastname: Mettenleiter
authors.forename: G M
authors.initials: GM
authors.lastname: Keil
mesh_terms: D000818:Animals; D000906:Antibodies; D015139:Blotting, Southern; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D015870:Gene Expression; D005804:Genes, Lethal; D005814:Genes, Viral; D016679:Genome, Viral; D007242:Herpesvirus 1, Bovine / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D015183:Restriction Mapping; D014162:Transfection; D014764:Viral Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism
chemical_list: D000906:Antibodies; D004279:DNA, Viral; D014764:Viral Proteins; C046998:bovine herpesvirus type-1 glycoproteins; D004247:DNA