title: Establishment of Vero E6 cell clones persistently infected with severe acute respiratory syndrome coronavirus.
abstract: Little information is available on persistent infection of severe acute respiratory syndrome (SARS) coronavirus (CoV). In this study, we established persistent infection of SARS-CoV in the Vero E6 cell line. Acute infection of Vero E6 with SARS-CoV produced a lytic infection with characteristic rounding cytopathic effects (CPE) and the production of a large number of infectious particles in the culture fluid within 3 days post-infection. Upon subsequent culturing of the remaining adherent cells, the cells gradually proliferated and recovered normal morphology similar to that of the parental cells, and continued to produce large numbers of infectious viral particles during the observation period of 5 months. Among a total of 87 cell clones obtained from the persistently infected Vero E6, only four cell clones (named #13, #18, #21, and #34) were positive for viral RNA. Clones #13, #18, and #34 shifted to viral RNA-negative during subsequent cultures, while #21 continuously produced infectious particles at a high rate. The SARS-CoV receptor, angiotensin-converting enzyme 2, was almost completely down regulated from the cell surface of persistently infected cells. Western blot analysis as well as electron microscopy indicated that the ratios of spike to nucleocapsid protein in clone #21 as well as its parental persistently infected cells were lower than that in the cells in the acute phase of infection. These Vero E6 cells persistently infected with SARS-CoV may be useful for clarifying the mechanism of the persistent infection and also for elucidating the possible pathophysiologic significance of such long-term maintenance of this virus.
authors.affiliation: Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Yamate
authors.forename: Makiko
authors.initials: M
authors.lastname: Yamashita
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Goto
authors.forename: Shoutaro
authors.initials: S
authors.lastname: Tsuji
authors.forename: Yong-Gang
authors.initials: YG
authors.lastname: Li
authors.forename: Jiranan
authors.initials: J
authors.lastname: Warachit
authors.forename: Mikihiro
authors.initials: M
authors.lastname: Yunoki
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ikuta
mesh_terms: D000085962:Angiotensin-Converting Enzyme 2; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D015153:Blotting, Western; D002268:Carboxypeptidases / Q000032:analysis; D002522:Chlorocebus aethiops; D003588:Cytopathogenic Effect, Viral; D015536:Down-Regulation; D005434:Flow Cytometry; D008562:Membrane Glycoproteins / Q000032:analysis; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D019590:Nucleocapsid Proteins / Q000032:analysis; D007703:Peptidyl-Dipeptidase A; D012367:RNA, Viral / Q000032:analysis; D045473:Severe acute respiratory syndrome-related coronavirus / Q000254:growth & development*; D064370:Spike Glycoprotein, Coronavirus; D014709:Vero Cells / Q000821:virology*; D014759:Viral Envelope Proteins / Q000032:analysis
chemical_list: D000954:Antigens, Surface; D008562:Membrane Glycoproteins; D019590:Nucleocapsid Proteins; D012367:RNA, Viral; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; D002268:Carboxypeptidases; D007703:Peptidyl-Dipeptidase A; D000085962:Angiotensin-Converting Enzyme 2