Project description:Omicron is currently the dominant SARS-CoV-2 variant and several sublineages have emerged. Questions remain about the impact of previous SARS-CoV-2 exposure on cross-variant immune responses elicited by the SARS-CoV-2 Omicron sublineage BA.2 compared to BA.1. Here we show that without previous history of COVID-19, BA.2 infection induces a reduced immune response against all variants of concern (VOC) compared to BA.1 infection. The absence of ACE2 binding in sera of previously naïve BA.1 and BA.2 patients indicates a lack of meaningful neutralization. In contrast, anti-spike antibody levels and neutralizing activity greatly increased in the BA.1 and BA.2 patients with a previous history of COVID-19. Transcriptome analyses of peripheral immune cells showed significant differences in immune response and specific antibody generation between BA.1 and BA.2 patients as well as significant differences in the expression of specific immune genes. In summary, prior infection status significantly impacts the innate and adaptive immune response against VOC following BA.2 infection.
Project description:RNA-Seq was used to study changes in gene expression in saliva samples from 266 human subjects after SARS-COV-2 infection, vaccination, or combined infection and vaccination (breakthrough). Approximately equal numbers of males and females, matched for age, were profiled after subjects tested positive for COVID-19 by PCR and sequencing of the variant. In addition to samples from uninfected controls with and without vaccination, samples from infected subjects with and without vaccination that represent eight major SARS-COV-2 lineages are included: epsilon, iota, alpha, delta, omicron BA.1, omicron BA.2, omicron BA.4, and omicron BA.5. Stranded single-end sequencing was performed using standard Illumina protocols. Reads were quantified to hg38 human transcriptome using Salmon after adapter trimming. Quantified reads were filtered to remove features with fewer than one count in 80% of the samples, and normalized using TPM, followed by quantile and log2 transformation.
Project description:The ancestral SARS-CoV-2 strain that initiated the Covid-19 pandemic at the end of 2019 has rapidly mutated into multiple variants of concern with variable pathogenicity and increasing immune escape strategies. However, differences in host cellular antiviral responses upon infection with SARS-CoV-2 variants remains elusive. Leveraging whole cell proteomics, we determined host signalling pathways that are differentially modulated upon infection with the clinical isolates of the ancestral SARS-CoV-2 B.1 and the variants of concern Delta and Omicron BA.1. Our findings illustrate alterations in the global host proteome landscape upon infection with SARS-CoV-2 variants and the resulting host immune responses. Additionally, viral proteome kinetics reveal declining levels of viral protein expression during Omicron BA.1 infection when compared to ancestral B.1 and Delta variants, consistent with its reduced replication rates. Moreover, molecular assays reveal deferral activation of specific host antiviral signalling upon Omicron BA.1 and BA.2 infection. Our study provides an overview of host proteome profile of multiple SARS-CoV-2 variants and brings forth a better understanding of the instigation of key immune signalling pathways causative for the differential pathogenicity of SARS-CoV-2 variants.
Project description:To investigate the virological properties of a SARS-CoV-2 variant, Omicron BA.2, we generated chimeric recombinant viruses that express GFP and encodes the S gene of B.1.1 (ancestral D614G-bearing virus), Delta, BA.1 and BA.2. To verify the genome sequence of the working viruses, we performed viral RNA-sequencing of the viral stock.
Project description:To investigate the virological properties of SARS-CoV-2 variants, we amplified the clinical isolates of an early pandemic D614G-bearing isolate (B.1.1 lineage, strain TKYE610670; GISAID ID: EPI_ISL_479681), a Delta isolate (B.1.617.2 lineage, strain TKYTK1734; GISAID ID: EPI_ISL_2378732) and an Omicron isolate (BA.1 lineage, strain TY38-873; GISAID ID: EPI_ISL_7418017) and prepared the working viruses.
Project description:SARS-CoV-2 induces widespread transcriptomic changes in host cells upon infection, in part through activation and modulation of innate immunity pathways and downstream gene regulation. However, the mechanisms by which SARS-CoV-2 and its evolutionary variants differentially affect host cell transcriptomic states remain largely unclear. Through chromatin proteomic (iDAPT-MS) analysis, we found that although SARS-CoV-2 and other pathogenic coronaviruses exhibit similar proteomic shifts on chromatin, SARS-CoV-2 uniquely promotes TP53 nuclear accumulation and activation. Parallel assessment of SARS-CoV-2 viral protein expression on host chromatin states (ATAC-seq) identifies intracellular spike protein as a key determinant of virus-mediated chromatin accessibility changes. Multilevel chromatin profiling reveals increased TP53 nuclear accumulation, TP53-associated chromatin accessibility changes, and TP53 target gene activation upon expression of SARS-CoV-2 alpha (B.1.1.7) and delta (B.1.617.2) spike variants relative to the ancestral spike sequence. TP53, ACE2, and furin cleavage are required for these changes, driving decreased cellular proliferation, increased cellular senescence, and increased cytokine release. Finally, BA.1 but not BA.2, BA.2.12.1, nor BA.4/BA.5 spike expression leads to attenuated TP53 activity and fusogenicity relative to ancestral spike. Our findings implicate spike-mediated host TP53 activation as a “rheostat” of COVID-19 pathogenicity.
Project description:In this study a gene expression (i.e., RNAseq) analysis was performed in HEK293T-ACE2 cellular model upon infection with viral particle belonging to VOC Delta (MOI: 0.026) for 24 hours in order to have a global picture of the transcriptome landscape in response to early phase of infection of SARS-CoV-2 ( VOC Delta infection and to evaluate the role of Ca2+ in HEK293-ACE2 cellular model and transfer to homeostasis in SARS-COV-2 patients (by Pasqualino de Antonellis1-2* and Veronica Ferrucci 1-2* (first authors) et al. and Massimo Zollo1-2# (corresponding author). Manuscript in preparation 2022 July 15th 2022. Short title "ATP2B1 (PMCA1), regulated by FOXO3, influences susceptibility to severe COVID19".
Project description:The spike glycoprotein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mediates binding to the ACE2 receptor and subsequent membrane fusion. It exists in a range of conformations, including a closed state unable to bind the ACE2 receptor, and an open state that does so but displays more exposed antigenic surface. Spikes of variants of concern (VOCs) acquired amino acid changes linked to different opening probabilities, increased SARS-CoV-2 virulence and immune evasion. Here, using hydrogen-deuterium exchange mass spectrometry (HDX-MS), we analyzed the spike of the original Wuhan isolate, G614 mutant, spike of alpha, beta, delta and omicron VOCs and the isolated ancestral receptor binding domain (RBD) - in apo state and in complex with the ACE2 receptor. We identified changes in spike dynamics that we associated with the transition from closed to open conformation, to ACE2 binding, and to specific mutations in VOCs. We show that the RBD-associated subdomain plays a role in spike opening, whereas the NTD acts as a hotspot of conformational divergence of VOC spikes driving immune evasion. Alpha, beta and delta spikes assume predominantly open conformations and a strong ACE2 binding increases the dynamics of their core helices, priming spikes for fusion. Conversely, substitutions in omicron spike lead to predominantly binding-incompetent closed conformations, presumably enabling it to escape antibodies. At the same time, its core helices show characteristics of being pre-primed for fusion even in the absence of ACE2. These data inform on SARS-CoV-2 evolution and omicron variant emergence.
Project description:The spike glycoprotein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mediates binding to the ACE2 receptor and subsequent membrane fusion. It exists in a range of conformations, including a closed state unable to bind the ACE2 receptor, and an open state that does so but displays more exposed antigenic surface. Spikes of variants of concern (VOCs) acquired amino acid changes linked to different opening probabilities, increased SARS-CoV-2 virulence and immune evasion. Here, using hydrogen-deuterium exchange mass spectrometry (HDX-MS), we analyzed the spike of the original Wuhan isolate, G614 mutant, spike of alpha, beta, delta and omicron VOCs and the isolated ancestral receptor binding domain (RBD) - in apo state and in complex with the ACE2 receptor. We identified changes in spike dynamics that we associated with the transition from closed to open conformation, to ACE2 binding, and to specific mutations in VOCs. We show that the RBD-associated subdomain plays a role in spike opening, whereas the NTD acts as a hotspot of conformational divergence of VOC spikes driving immune evasion. Alpha, beta and delta spikes assume predominantly open conformations and a strong ACE2 binding increases the dynamics of their core helices, priming spikes for fusion. Conversely, substitutions in omicron spike lead to predominantly binding-incompetent closed conformations, presumably enabling it to escape antibodies. At the same time, its core helices show characteristics of being pre-primed for fusion even in the absence of ACE2. These data inform on SARS-CoV-2 evolution and omicron variant emergence.
Project description:Despite the wide availability of several safe and effective vaccines that can prevent severe COVID-19 disease, the emergence of SARS-CoV-2 variants of concern (VOC) that can partially evade vaccine immunity remains a global health concern. In addition, the emergence of highly mutated and neutralization-resistant SARS-CoV-2 VOCs such as BA.1 and BA.5 that can partially or fully evade (1) many therapeutic monoclonal antibodies in clinical use underlines the need for additional effective treatment strategies. Here, we characterize the antiviral activity of GS-5245, Obeldesivir (ODV), an oral prodrug of the parent nucleoside GS-441524, which targets the highly conserved RNA-dependent viral RNA polymerase (RdRp). Importantly, we show that GS-5245 is broadly potent in vitro against alphacoronavirus HCoV-NL63, severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-related Bat-CoV RsSHC014, Middle East Respiratory Syndrome coronavirus (MERS-CoV), SARS-CoV-2 WA/1, and the highly transmissible SARS-CoV-2 BA.1 Omicron variant in vitro and highly effective as antiviral therapy in mouse models of SARS-CoV, SARS-CoV-2 (WA/1), MERS-CoV and Bat-CoV RsSHC014 pathogenesis. In all these models of divergent coronaviruses, we observed protection and/or significant reduction of disease metrics such as weight loss, lung viral replication, acute lung injury, and degradation in pulmonary function in GS-5245-treated mice compared to vehicle controls. Finally, we demonstrate that GS-5245 in combination with the main protease (Mpro) inhibitor nirmatrelvir had increased efficacy in vivo against SARS-CoV-2 compared to each single agent. We also evalulate the effect of antiviral therapy on host gene expression using RNAseq and show that therapeutic intervention reduces host inflammatory response as compared to vehicle controls during acute SARS-CoV-2 infection. Altogether, our data supports the continuing clinical evaluation of GS-5245 in humans infected with COVID-19, including as part of a combination antiviral therapy, especially in populations with the most urgent need for more efficacious and durable interventions.