title: The herpes simplex virus UL20 protein compensates for the differential disruption of exocytosis of virions and viral membrane glycoproteins associated with fragmentation of the Golgi apparatus.
abstract: The Golgi apparatus is fragmented and dispersed in Vero cells but not in human 143TK- cells infected with wild-type herpes simplex virus 1. Moreover, a recombinant virus lacking the gene encoding the membrane protein UL20 (UL20- virus) accumulates in the space between the inner and outer nuclear membranes of Vero cells but is exported and spreads from cell to cell in 143TK- cell cultures. Here we report that in Vero cells infected with UL20- virus, the virion envelope glycoproteins were of the immature type, whereas the viral glycoproteins associated with cell membranes were fully processed up to the addition of sialic acid, a trans-Golgi function. Moreover, the amounts of viral glycoproteins accumulating in the plasma membranes were considerably smaller than those detected on the surface of Vero cells infected with wild-type virus. In contrast, the amounts of viral glycoproteins present on the plasma membranes of 143TK- cells infected with wild-type or UL20- virus were nearly identical. We conclude that (i) in Vero cells infected with UL20- virus the block in the export of virions is at the entry into the exocytic pathway, and a second block in the exocytosis of viral glycoproteins associated with cytoplasmic membranes is due to an impairment of transport beyond Golgi fragments containing trans-Golgi enzymes and not to a failure of the Golgi oligosaccharide-processing functions; (ii) these defects are manifested in cells in which the Golgi apparatus is fragmented; and (iii) the UL20 protein compensates for these defects by enabling transport to and from the fragmented Golgi apparatus.
authors.affiliation: Department of Experimental Pathology, University of Bologna, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Avitabile
authors.forename: P L
authors.initials: PL
authors.lastname: Ward
authors.forename: C
authors.initials: C
authors.lastname: Di Lazzaro
authors.forename: M R
authors.initials: MR
authors.lastname: Torrisi
authors.forename: B
authors.initials: B
authors.lastname: Roizman
authors.forename: G
authors.initials: G
authors.lastname: Campadelli-Fiume
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D005089:Exocytosis; D006056:Golgi Apparatus / Q000378:metabolism*; D018259:Herpesvirus 1, Human / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C040495:glycoprotein B, Simplexvirus; C039447:glycoprotein D, Human herpesvirus 1; C038535:glycoprotein gC, herpes simplex virus type 1