title: Beta1 integrin mediates internalization of mammalian reovirus.
abstract: Reovirus infection is initiated by interactions between the attachment protein sigma1 and cell surface carbohydrate and junctional adhesion molecule A (JAM-A). Expression of a JAM-A mutant lacking a cytoplasmic tail in nonpermissive cells conferred full susceptibility to reovirus infection, suggesting that cell surface molecules other than JAM-A mediate viral internalization following attachment. The presence of integrin-binding sequences in reovirus outer capsid protein lambda2, which serves as the structural base for sigma1, suggests that integrins mediate reovirus endocytosis. A beta1 integrin-specific antibody, but not antibodies specific for other integrin subunits, inhibited reovirus infection of HeLa cells. Expression of a beta1 integrin cDNA, along with a cDNA encoding JAM-A, in nonpermissive chicken embryo fibroblasts conferred susceptibility to reovirus infection. Infectivity of reovirus was significantly reduced in beta1-deficient mouse embryonic stem cells in comparison to isogenic cells expressing beta1. However, reovirus bound equivalently to cells that differed in levels of beta1 expression, suggesting that beta1 integrins are involved in a postattachment entry step. Concordantly, uptake of reovirus virions into beta1-deficient cells was substantially diminished in comparison to viral uptake into beta1-expressing cells. These data provide evidence that beta1 integrin facilitates reovirus internalization and suggest that viral entry occurs by interactions of reovirus virions with independent attachment and entry receptors on the cell surface.
authors.affiliation: Department of Microbiology and Immunology, Lamb Center for Pediatric Research, D7235 MCN, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Maginnis
authors.forename: J Craig
authors.initials: JC
authors.lastname: Forrest
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Kopecky-Bromberg
authors.forename: S Kent
authors.initials: SK
authors.lastname: Dickeson
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Santoro
authors.forename: Mary M
authors.initials: MM
authors.lastname: Zutter
authors.forename: Glen R
authors.initials: GR
authors.lastname: Nemerow
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Bergelson
authors.forename: Terence S
authors.initials: TS
authors.lastname: Dermody
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D006224:Cricetinae; D006367:HeLa Cells; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D062726:Junctional Adhesion Molecules; D007739:L Cells; D012089:Mammalian orthoreovirus 3 / Q000472:pathogenicity; D051379:Mice; D008969:Molecular Sequence Data; D030102:Orthoreovirus, Mammalian / Q000472:pathogenicity*; D011991:Receptors, Virus / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; D015815:Cell Adhesion Molecules; D019012:Integrin beta1; D062726:Junctional Adhesion Molecules; D011991:Receptors, Virus