Ultrastructural analysis and three-dimensional reconstruction of cellular structures involved in SARS-CoV-2 spread

Abstract

The cytoskeleton not only deals with numerous interaction and communication mechanisms at the cellular level but also has a crucial role in the viral infection cycle. Although numerous aspects of SARS-CoV-2 virus interaction at the cellular level have been widely studied, little has been reported about the structural and functional response of the cytoskeleton. This work aims to characterize, at the ultrastructural level, the modifications in the cytoskeleton of infected cells, namely, its participation in filopodia formation, the junction of these nanostructures forming bridges, the viral surfing, and the generation of tunnel effect nanotubes (TNT) as probable structures of intracellular viral dissemination. The three-dimensional reconstruction from the obtained micrographs allowed observing viral propagation events between cells in detail for the first time. More profound knowledge about these cell-cell interaction models in the viral spread mechanisms could lead to a better understanding of the clinical manifestations of COVID-19 disease and to find new therapeutic strategies.

Comparative analysis of SARS-CoV-2 variants Alpha (B.1.1.7), Gamma (P.1), Zeta (P.2) and Delta (B.1.617.2) in Vero-E6 cells: ultrastructural characterization of cytopathology and replication kinetics

“…Previous in vitro studies by our group 36 and Baselga et al 48 reported that the virus induces filopodium formation to maximize the infection process. It is also known that viral particles are highly concentrated in this region of filopodia, facilitating contact with the membrane of new cells.…”

In focus in HCB

“…Although many ultrastructural investigations to track the SARS-CoV-2 infection life cycle and effects on cellular organelles have been performed (for instance, see Barreto-Vieira et al 2022 ), little attention has been paid to the role of the cytoskeleton in these processes, though it is known to be involved in replication of other viruses (Foo and Chee 2015 ). To this end, Baselga et al ( 2022 ) have performed a transmission electron microscopic investigation of SARS-CoV-2 infection of Vero E6 cultured cells, with particular attention focused on the role of cytoskeletal elements in virus infection and transmission between neighboring cells. To help ultrastructurally identify the cytoplasmic structures involved in the viral infection and spreading process, the authors cut serial sections from embedded cell cultures, acquired images, and performed three-dimensional reconstructions.…”