title: Echovirus 1 infection depends on biogenesis of novel multivesicular bodies.
abstract: Non-enveloped picornavirus echovirus 1 (EV1) clusters its receptor α2β1 integrin and causes their internalization and accumulation in α2β1 integrin enriched multivesicular bodies (α2-MVBs). Our results here show that these α2-MVBs are distinct from acidic late endosomes/lysosomes by several criteria: (i) live intra-endosomal pH measurements show that α2-MVBs are not acidic, (ii) they are not positive for the late endosomal marker LBPA or Dil-LDL internalized to lysosomes, and (iii) simultaneous stimulation of epidermal growth factor receptor (EGFR) and α2β1 integrin clustering leads to their accumulation in separate endosomes. EGFR showed downregulation between 15 min and 2 h, whereas accumulation of α2β1 integrin/EV1 led to an increase of integrin fluorescence in cytoplasmic vesicles further suggesting that EV1 pathway is separate from the lysosomal downregulation pathway. In addition, the results demonstrate the involvement of ESCRTs in the biogenesis of α2-MVBs. Overexpression of dominant-negative form of VPS4 inhibited biogenesis of α2-MVBs and efficiently prevented EV1 infection. Furthermore, α2-MVBs were positive for some members of ESCRTs such as Hrs, VPS37A and VPS24 and the siRNA treatment of TSG101, VPS37A and VPS24 inhibited EV1 infection. Our results show that the non-enveloped EV1 depends on biogenesis of novel multivesicular structures for successful infection.
authors: Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, FI-40351 Jyväskylä, Finland.
authors: Mikko
authors: M
authors: Karjalainen
authors: Nina
authors: N
authors: Rintanen
authors: Moona
authors: M
authors: Lehkonen
authors: Katri
authors: K
authors: Kallio
authors: Anita
authors: A
authors: Mäki
authors: Kirsi
authors: K
authors: Hellström
authors: Valtteri
authors: V
authors: Siljamäki
authors: Paula
authors: P
authors: Upla
authors: Varpu
authors: V
authors: Marjomäki
mesh_terms: D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000378:metabolism / Q000821:virology*; D004457:Echovirus Infections / Q000821:virology*; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism; D029822:Enterovirus B, Human / Q000472:pathogenicity*; D066246:ErbB Receptors / Q000378:metabolism; D005453:Fluorescence; D006801:Humans; D006863:Hydrogen-Ion Concentration; D038982:Integrin alpha2beta1 / Q000378:metabolism; D034741:RNA, Small Interfering; D011991:Receptors, Virus / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D038982:Integrin alpha2beta1; D034741:RNA, Small Interfering; D011991:Receptors, Virus; D066246:ErbB Receptors