title: Vaccinia virus utilizes microtubules for movement to the cell surface.
abstract: Vaccinia virus (VV) egress has been studied using confocal, video, and electron microscopy. Previously, intracellular-enveloped virus (IEV) particles were proposed to induce the polymerization of actin tails, which propel IEV particles to the cell surface. However, data presented support an alternative model in which microtubules transport virions to the cell surface and actin tails form beneath cell-associated enveloped virus (CEV) particles at the cell surface. Thus, VV is unique in using both microtubules and actin filaments for egress. The following data support this proposal. (a) Microscopy detected actin tails at the surface but not the center of cells. (b) VV mutants lacking the A33R, A34R, or A36R proteins are unable to induce actin tail formation but produce CEV and extracellular-enveloped virus. (c) CEV formation is inhibited by nocodazole but not cytochalasin D or 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine (PP1). (d) IEV particles tagged with the enhanced green fluorescent protein fused to the VV B5R protein moved inside cells at 60 microm/min. This movement was stop-start, was along defined pathways, and was inhibited reversibly by nocodazole. This velocity was 20-fold greater than VV movement on actin tails and consonant with the rate of movement of organelles along microtubules.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Hollinshead
authors.forename: G
authors.initials: G
authors.lastname: Rodger
authors.forename: H
authors.initials: H
authors.lastname: Van Eijl
authors.forename: M
authors.initials: M
authors.lastname: Law
authors.forename: R
authors.initials: R
authors.lastname: Hollinshead
authors.forename: D J
authors.initials: DJ
authors.lastname: Vaux
authors.forename: G L
authors.initials: GL
authors.lastname: Smith
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure / Q000821:virology*; D004722:Endoribonucleases; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure / Q000821:virology*; D015739:Nocodazole / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases; D010766:Phosphorylation / Q000187:drug effects; D016601:RNA-Binding Proteins / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D014616:Vaccinia virus / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D014759:Viral Envelope Proteins / Q000235:genetics; D015678:Viral Structural Proteins / Q000378:metabolism
chemical_list: C400287:A36R protein, Vaccinia virus; D000199:Actins; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014759:Viral Envelope Proteins; D015678:Viral Structural Proteins; C021042:protein phosphatase inhibitor-1; C074512:42kDa protein, Vaccinia virus; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D004722:Endoribonucleases; D010749:Phosphoprotein Phosphatases; C097081:PPP1R8 protein, human; D015739:Nocodazole