title: The open reading frame 3a protein of severe acute respiratory syndrome-associated coronavirus promotes membrane rearrangement and cell death.
abstract: The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.
authors.affiliation: Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Freundt
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Goldsmith
authors.forename: Sarah
authors.initials: S
authors.lastname: Welsh
authors.forename: Aaron
authors.initials: A
authors.lastname: Cheng
authors.forename: Boyd
authors.initials: B
authors.lastname: Yount
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Frieman
authors.forename: Ursula J
authors.initials: UJ
authors.lastname: Buchholz
authors.forename: Gavin R
authors.initials: GR
authors.lastname: Screaton
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
authors.forename: Sherif R
authors.initials: SR
authors.lastname: Zaki
authors.forename: Xiao-Ning
authors.initials: XN
authors.lastname: Xu
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Baric
authors.forename: Kanta
authors.initials: K
authors.lastname: Subbarao
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lenardo
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016923:Cell Death; D002462:Cell Membrane / Q000473:pathology / Q000821:virology; D002522:Chlorocebus aethiops; D022162:Cytoplasmic Vesicles / Q000378:metabolism / Q000821:virology; D017353:Gene Deletion; D006056:Golgi Apparatus / Q000378:metabolism / Q000473:pathology; D054884:Host-Pathogen Interactions; D006801:Humans; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D014162:Transfection; D014709:Vero Cells / Q000473:pathology; D015678:Viral Structural Proteins / Q000378:metabolism*; D000086082:Viroporin Proteins
chemical_list: D020823:ADP-Ribosylation Factor 1; D015678:Viral Structural Proteins; C515313:ORF3A protein, SARS coronavirus; D000086082:Viroporin Proteins