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APR 05, 2022 9:00 AM PDT

Enterovirus membrane-assisted assembly and release revealed by cryo-electron tomography

Speakers

Abstract
Date:  April 5, 2022
Time: 9:00am (PDT), 12:00pm (EDT), 6:00pm (CEST)
 
Enteroviruses are non-enveloped positive-sense RNA viruses that cause diverse diseases in humans. Their rapid multiplication depends on remodeling of cytoplasmic membranes for viral genome replication. It is unknown how virions assemble around these newly synthesized genomes and how they are then loaded into autophagic membranes for release through secretory autophagy. Here, we use cryo-electron tomography of infected cells to show that poliovirus assembles directly on replication membranes. Pharmacological untethering of capsids from membranes abrogates RNA encapsidation. Our data directly visualize a membrane-bound half-capsid as a prominent virion assembly intermediate. Assembly progression past this intermediate depends on the class III phosphatidylinositol 3-kinase VPS34, a key host-cell autophagy factor. On the other hand, the canonical autophagy initiator ULK1 is shown to restrict virion production since its inhibition leads to increased accumulation of virions in vast intracellular arrays, followed by an increased vesicular release at later time points. Finally, we identify multiple layers of selectivity in virus-induced autophagy, with a strong selection for RNA-loaded virions over empty capsids and the segregation of virions from other types of autophagosome contents. These findings provide an integrated structural framework for multiple stages of the poliovirus life cycle.
 
Learning Objectives
  • Discuss how the poliovirus reshapes the membranes of infected cells during replication
  • Visualize how virions assemble directly on replication membranes
  • Reveal with in situ cryo-electron tomography the interplay between poliovirus and cellular autophagy
 
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LabRoots is approved as a provider of continuing education programs in the clinical laboratory sciences by the ASCLS P.A.C.E. ® Program. By attending this webinar, you can earn 1 Continuing Education credit once you have viewed the webinar in its entirety.

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