title: Internalization of echovirus 1 in caveolae.
abstract: Echovirus 1 (EV1) is a human pathogen which belongs to the Picornaviridae family of RNA viruses. We have analyzed the early events of infection after EV1 binding to its receptor alpha 2 beta 1 integrin and elucidated the route by which EV1 gains access to the host cell. EV1 binding onto the cell surface and subsequent entry resulted in conformational changes of the viral capsid as demonstrated by sucrose gradient sedimentation analysis. After 15 min to 2 h postinfection (p.i.) EV1 capsid proteins were seen in vesicular structures that were negative for markers of the clathrin-dependent endocytic pathway. In contrast, immunofluorescence confocal microscopy showed that EV1, alpha 2 beta 1 integrin, and caveolin-1 were internalized together in vesicular structures to the perinuclear area. Electron microscopy showed the presence of EV1 particles inside caveolae. Furthermore, infective EV1 could be isolated with anti-caveolin-1 beads 15 min p.i., confirming a close association with caveolin-1. Finally, the expression of dominant negative caveolin in cells markedly inhibited EV1 infection, indicating the importance of caveolae for the viral replication cycle of EV1.
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, Finland. vmarjoma@cc.jyu.fi
authors.forename: Varpu
authors.initials: V
authors.lastname: Marjomäki
authors.forename: Vilja
authors.initials: V
authors.lastname: Pietiäinen
authors.forename: Heli
authors.initials: H
authors.lastname: Matilainen
authors.forename: Paula
authors.initials: P
authors.lastname: Upla
authors.forename: Johanna
authors.initials: J
authors.lastname: Ivaska
authors.forename: Liisa
authors.initials: L
authors.lastname: Nissinen
authors.forename: Hilkka
authors.initials: H
authors.lastname: Reunanen
authors.forename: Pasi
authors.initials: P
authors.lastname: Huttunen
authors.forename: Timo
authors.initials: T
authors.lastname: Hyypiä
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heino
mesh_terms: D000818:Animals; D002213:Capsid / Q000378:metabolism; D021941:Caveolae / Q000648:ultrastructure / Q000821:virology*; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D029822:Enterovirus B, Human / Q000472:pathogenicity* / Q000648:ultrastructure; D004769:Enterovirus Infections / Q000821:virology*; D006801:Humans; D016023:Integrins / Q000378:metabolism; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D011817:Rabbits; D038981:Receptors, Collagen; D014407:Tumor Cells, Cultured / Q000648:ultrastructure / Q000821:virology; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D002966:Clathrin; D016023:Integrins; D038981:Receptors, Collagen; D001613:beta 2-Microglobulin