Biology subjects

Taddeo, A.

Publications and source records attributed to Taddeo, A..

3 recordsLinked to original sources

bioRxiv2021

Enhanced fitness of SARS-CoV-2 variant of concern B.1.1.7, but not B.1.351, in animal models

Emerging variants of concern (VOCs) drive the SARS-CoV-2 pandemic. We assessed VOC B.1.1.7, now prevalent in several countries, and VOC B.1.351, representing the greatest threat to populations with immunity to the early SARS-CoV-2 progenitors. B.1.1.7 showed a clear fitness advantage over the progenitor variant (wt-S614G) in ferrets and two mouse models, where the substitutions in the spike glycoprotein were major drivers for fitness advantage. In the "superspreader" hamster model, B.1.1.7 and wt-S614G had comparable fitness, whereas B.1.351 was outcompeted. The VOCs had similar replication kinetics as compared to wt-S614G in human airway epithelial cultures. Our study highlights the importance of using multiple models for complete fitness characterization of VOCs and demonstrates adaptation of B.1.1.7 towards increased upper respiratory tract replication and enhanced transmission in vivo. Summary sentenceB.1.1.7 VOC outcompetes progenitor SARS-CoV-2 in upper respiratory tract replication competition in vivo.

microbiology↗

bioRxiv2020

SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

During the evolution of SARS-CoV-2 in humans a D614G substitution in the spike (S) protein emerged and became the predominant circulating variant (S-614G) of the COVID-19 pandemic1. However, whether the increasing prevalence of the S-614G variant represents a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains elusive. Here, we generated isogenic SARS-CoV-2 variants and demonstrate that the S-614G variant has (i) enhanced binding to human ACE2, (ii) increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a novel human ACE2 knock-in mouse model, and (iii) markedly increased replication and transmissibility in hamster and ferret models of SARS-CoV-2 infection. Collectively, our data show that while the S-614G substitution results in subtle increases in binding and replication in vitro, it provides a real competitive advantage in vivo, particularly during the transmission bottle neck, providing an explanation for the global predominance of S-614G variant among the SARS-CoV-2 viruses currently circulating.

microbiology↗

bioRxiv2019

Stromal cell-contact dependent PI3K and APRIL induced NF-κB signaling complement each other to prevent mitochondrial- and endoplasmic reticulum stress induced cell death of bone marrow plasma cells

Persistence of long-lived, memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, provided in niches organized by stromal cells. Here we describe that ex vivo we can prevent apoptosis of bone marrow plasma cells by supplying direct cell contact with stromal cells and the soluble cytokine APRIL. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the PI3K signaling pathway, leading to critical inactivation of FoxO1/3 and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Likely, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, via the NF-{kappa}B pathway, blocks activation of the endoplasmic reticulum stress-associated initiator caspase 12. Thus, stromal cell-contact induced PI3K and APRIL-induced NF-{kappa}B signaling provide necessary and complementary signals to maintain bone marrow memory plasma cells.

immunology↗