title: Vesicle formation from the nuclear membrane is induced by coexpression of two conserved herpesvirus proteins.
abstract: Although the nuclear envelope is a dynamic structure that disassembles and reforms during mitosis, the formation of membranous vesicles derived from the nuclear envelope has not yet been described in noninfected cells. However, during herpesvirus maturation, intranuclear capsids initiate transit to the cytosol for final maturation by budding at the inner nuclear membrane. Two conserved herpesvirus proteins are required for this primary envelopment, designated in the alphaherpesviruses as pUL31 and pUL34. Here, we show that simultaneous expression of pUL31 and pUL34 of the alphaherpesvirus pseudorabies virus in stably transfected rabbit kidney cells resulted in the formation of vesicles in the perinuclear space that resemble primary envelopes without a nucleocapsid. They contain pUL31 and pUL34 as shown by immunolabeling and are derived from the nuclear envelope. Thus, coexpression of only two conserved herpesvirus proteins without any other viral factor is sufficient to induce the formation of vesicles from the nuclear membrane. This argues for the contribution of cellular factors in this process either recruited from their natural cytoplasmic location or not yet identified as components of the nuclear compartment.
authors.affiliation: Institute of Molecular Biology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany.
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Klupp
authors.forename: Harald
authors.initials: H
authors.lastname: Granzow
authors.forename: Walter
authors.initials: W
authors.lastname: Fuchs
authors.forename: Günther M
authors.initials: GM
authors.lastname: Keil
authors.forename: Stefan
authors.initials: S
authors.lastname: Finke
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Mettenleiter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D017124:Conserved Sequence; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D006564:Herpesviridae / Q000254:growth & development / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D051379:Mice; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D009154:Mutation / Q000235:genetics; D009685:Nuclear Envelope / Q000378:metabolism* / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000378:metabolism*; D021381:Protein Transport; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins; C108721:UL31 protein, Human herpesvirus 1; C403420:UL34 protein, Human herpesvirus 1; D014764:Viral Proteins