Essential role of TMPRSS2 in SARS-CoV-2 infection in murine airways

Abstract

In cultured cells, SARS-CoV-2 infects cells via multiple pathways using different host proteases. Recent studies have shown that the furin and TMPRSS2 (furin/TMPRSS2)-dependent pathway plays a minor role in infection of the Omicron variant. Here, we confirm that Omicron uses the furin/TMPRSS2-dependent pathway inefficiently and enters cells mainly using the cathepsin-dependent endocytosis pathway in TMPRSS2-expressing VeroE6/TMPRSS2 and Calu-3 cells. This is the case despite efficient cleavage of the spike protein of Omicron. However, in the airways of TMPRSS2-knockout mice, Omicron infection is significantly reduced. We furthermore show that propagation of the mouse-adapted SARS-CoV-2 QHmusX strain and human clinical isolates of Beta and Gamma is reduced in TMPRSS2-knockout mice. Therefore, the Omicron variant isn’t an exception in using TMPRSS2 in vivo, and analysis with TMPRSS2-knockout mice is important when evaluating SARS-CoV-2 variants. In conclusion, this study shows that TMPRSS2 is critically important for SARS-CoV-2 infection of murine airways, including the Omicron variant.

Improving Nasal Protection for Preventing SARS-CoV-2 Infection

“…Briefly, reliable evidence has been provided that the Omicron sublineages, other than replicating prevalently in the upper respiratory tract [ 12 ], may also penetrate the host cell by endocytosis and sorting within endolysosomes, employing an acid-activated cathepsin L mechanism [ 13 ]. This evidence has been recently confirmed by an elegant study published by Iwata–Yoshikawa et al [ 14 ], who showed that Omicron sublineages seem to use the furin/TMPRSS2-dependent entrance pathway less efficiently, thus penetrating the host cells prevalently through a cathepsin-dependent endocytosis pathway in TMPRSS2-expressing cells. Cell to cell transmission is a third important mechanism that has been elucidated for explaining host cell penetration by SARS-CoV-2, whereby endosomal membrane fusion [ 15 ] or generation of syncytia mediated by the binding of spike protein expressed on the surface of infected cells with ACE2 present in adjacent and uninfected cells [ 16 ] may allow the spread of the virus in the nearby respiratory tissue.…”

Phenothiazines inhibit SARS-CoV-2 cell entry via a blockade of spike protein binding to neuropilin-1

“…5 B and C), suggesting that alimemazine inhibits SARS2-S-mediated cell entry through a mechanism similar to that used by the DRD2 antagonists. The serine protease TMPRSS2 plays a critical role in SARS-CoV-2 infection in vivo ( Iwata-Yoshikawa et al, 2022a ). We then assessed the inhibitory effect of alimemazine on VSV-based pseudovirus cell entry in Vero E6 cells expressing TMPRSS2 (VeroE6/TMPRSS2).…”

Increased neurovirulence of omicron BA.5 and XBB variants over BA.1 in K18-hACE2 mice and human brain organoids

“…The BA.1 and BA.5 isolates used herein have 14 amino acid differences in the spike protein (Supplementary Table 3). Pathogenicity has been shown to be dependent on TMPRSS2 utilization 109 , with TMPRSS2 utilization reported to be a virulence determinant, even for omicron variants 110 . Treatment with a TMPRSS2 inhibitor also prevented brain infection in K18-hACE2 mice 111 .…”