title: Human cytomegalovirus tegument protein ppUL35 is important for viral replication and particle formation.
abstract: The tegument proteins ppUL35 and ppUL82 (pp71) of human cytomegalovirus (HCMV) physically interact and cooperatively activate the major immediate-early transcription. While an HCMV mutant lacking UL82 displayed a multiplicity of infection (MOI)-dependent growth, the biological significance of ppUL35 has not been addressed so far. We generated a mutant virus with a deletion of the UL35 gene. Using an MOI of 0.1, the progeny virus yield of this mutant was reduced by a factor of 1,000; however, when infected at a low MOI (0.01), the gene was essential. Characterization of the replication cycle showed that the mutant virus had two defects: when virus inoculum was standardized by the amount of viral DNA, a reduced immediate-early gene expression was observed, leading to a strongly delayed expression of lytic genes. A second defect was apparent in the virus assembly, as fewer enveloped particles and no dense bodies were present in cells infected with the mutant virus. However, the particles produced by wild-type and mutant viruses did not show significant ultrastructural differences. These results suggest an important role for ppUL35 in immediate-early gene expression and virus assembly.
authors.affiliation: Abteilung Virologie, Universitätsklinikum Ulm, Albert Einstein Allee 11, D-89081 Ulm, Germany. michael.winkler@medizin.uni-ulm.de
authors.forename: Karina
authors.initials: K
authors.lastname: Schierling
authors.forename: Christopher
authors.initials: C
authors.lastname: Buser
authors.forename: Thomas
authors.initials: T
authors.lastname: Mertens
authors.forename: Michael
authors.initials: M
authors.lastname: Winkler
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D003587:Cytomegalovirus / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D004279:DNA, Viral / Q000235:genetics; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D017781:Genes, Immediate-Early; D005814:Genes, Viral; D006801:Humans; D008854:Microscopy, Electron; D016296:Mutagenesis; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D019065:Virus Assembly / Q000235:genetics / Q000502:physiology; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; C051298:cytomegalovirus phosphoprotein 71kDa