Ultrastructural insight into SARS-CoV-2 entry and budding in human airway epithelium.


Type
Article
Change log
Authors
Pinto, Andreia L 
Rai, Ranjit K 
Griffin, Paul 
Abstract

Ultrastructural studies of SARS-CoV-2 infected cells are crucial to better understand the mechanisms of viral entry and budding within host cells. Here, we examined human airway epithelium infected with three different isolates of SARS-CoV-2 including the B.1.1.7 variant by transmission electron microscopy and tomography. For all isolates, the virus infected ciliated but not goblet epithelial cells. Key SARS-CoV-2 entry molecules, ACE2 and TMPRSS2, were found to be localised to the plasma membrane including microvilli but excluded from cilia. Consistently, extracellular virions were seen associated with microvilli and the apical plasma membrane but rarely with ciliary membranes. Profiles indicative of viral fusion where tomography showed that the viral membrane was continuous with the apical plasma membrane and the nucleocapsids diluted, compared with unfused virus, demonstrate that the plasma membrane is one site of entry where direct fusion releasing the nucleoprotein-encapsidated genome occurs. Intact intracellular virions were found within ciliated cells in compartments with a single membrane bearing S glycoprotein. Tomography showed concentration of nucleocapsids round the periphery of profiles strongly suggestive of viral budding into these compartments and this may explain how virions gain their S glycoprotein containing envelope.

Description

Funder: G2P-UK National Virology Consortium funded by UKRI

Keywords
COVID-19, Epithelium, Humans, Peptidyl-Dipeptidase A, SARS-CoV-2
Journal Title
Nat Commun
Conference Name
Journal ISSN
2041-1723
2041-1723
Volume Title
13
Publisher
Springer Science and Business Media LLC
Sponsorship
Wellcome Trust (216370/Z/19/Z)