Project description:The open reading frame (ORF) 8 in severe acute respiratory syndrome coronaviruses (SARS-CoVs), associated with host adaptation and viral replication, is a hotspot for mutation. However, mutation effects on host immune responses remain unknown. Here, whole blood transcriptomics performed on patients infected with mutant SARS-CoV-2 (Δ382; 382-nt deletion in ORF8) show differing profiles from wildtype SARS-CoV-2. Understanding the Δ382 mechanism and effects would allow for a focused approach in vaccine and antiviral development.
Project description:All coronaviruses known to have recently emerged as human pathogens probably originated in bats1. Here we use a single experimental platform based on immunodeficient mice implanted with human lung tissue (hereafter, human lung-only mice (LoM)) to demonstrate the efficient in vivo replication of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as two endogenous SARS-like bat coronaviruses that show potential for emergence as human pathogens. Virus replication in this model occurs in bona fide human lung tissue and does not require any type of adaptation of the virus or the host. Our results indicate that bats contain endogenous coronaviruses that are capable of direct transmission to humans. Our detailed analysis of in vivo infection with SARS-CoV-2 in human lung tissue from LoM showed a predominant infection of human lung epithelial cells, including type-2 pneumocytes that are present in alveoli and ciliated airway cells. Acute infection with SARS-CoV-2 was highly cytopathic and induced a robust and sustained type-I interferon and inflammatory cytokine and chemokine response. Finally, we evaluated a therapeutic and pre-exposure prophylaxis strategy for SARS-CoV-2 infection. Our results show that therapeutic and prophylactic administration of EIDD-2801?an oral broad-spectrum antiviral agent that is currently in phase II/III clinical trials?markedly inhibited SARS-CoV-2 replication in vivo, and thus has considerable potential for the prevention and treatment of COVID-19.
Project description:Severe acute respiratory syndrome coronavirus (SARS-CoV) causes a respiratory disease leading to death in 10% of the infected people. A mouse adapted SARS-CoV lacking the envelope (E) protein (rSARS-CoV-MA15-?E) is attenuated in vivo. To identify E protein domains and host responses that contribute to rSARS-CoV-MA15-?E attenuation, several mutants (rSARS-CoV-MA15-E*) containing point mutations or deletions in the amino-terminal or the carboxy-terminal regions of E protein, respectively, were generated. Amino acid substitutions in the amino terminus, or deletion of domains in the internal carboxy terminal region of E protein led to viral attenuation. Attenuated viruses induced minimal lung injury and limited neutrophil influx to the lungs but, interestingly, increased CD4+ and CD8+ T cell counts in BALB/c mice. To analyze the host responses leading to rSARS-CoV-MA15-E* attenuation, the differential gene expression elicited by the native virus and the mutant ones in infected cells was analyzed. The expression levels of a large number of proinflammatory cytokines inducing lung injury was reduced in the lungs of rSARS-CoV-MA15-E* infected mice, whereas the levels of anti-inflammatory cytokines were increased, both at the mRNA and protein levels. These results suggested that the reduction in lung inflammation together with a specific antiviral T cell response, contributed to rSARS-CoV-MA15-E* attenuation. Interestingly, the attenuated viruses completely protected mice against the challenge with the lethal parental virus, being promising vaccine candidates. Three biological replicates were independently hybridized (one channel per slide) for each sample type (rSARS-CoV-MA15-wt, rSARS-CoV-MA15-?E, rSARS-CoV-MA15-?3, rSARS-CoV-MA15-?5, Mock). Slides were Sure Print G3 Agilent 8x60K Mouse (G4852A-028005)
Project description:Background: The recent emergence of a novel coronavirus in the Middle East (designated MERS-CoV) is a reminder of the zoonotic potential of coronaviruses and the severe disease these etiologic agents can cause in humans. Clinical features of Middle East respiratory syndrome (MERS) include severe acute pneumonia and renal failure that is highly reminiscent of severe acute respiratory syndrome (SARS) caused by SARS-CoV. The host response is a key component of highly pathogenic respiratory virus infection. Here, we computationally analyzed gene expression changes in a human airway epithelial cell line infected with two genetically distinct MERS-CoV strains obtained from human patients, MERS-CoV-EMC (designated EMC) and MERS-CoV-London (designated LoCoV). Results: Using topological techniques, such as persistence homology and filtered clustering, we characterized the host response system to the different MERS-CoVs, with LoCoV inducing early kinetic changes, between 3 and 12 hours post infection, compared to EMC. Robust transcriptional changes distinguished the two MERS-CoV strains predominantly at the late time points. Combining statistical analysis of infection and cytokine-stimulated treatment transcriptomics, we identified differential innate and pro-inflammatory responses between the two virus strains, including up-regulation of extracellular remodeling genes following LoCoV infection and differential pro-inflammatory responses between the two strains. Conclusions: These transcriptional differences may be the result of amino acid differences in viral proteins known to modulate innate immunity against MERS infection. Triplicate wells of Calu-3 2B4 cells were infected with Human Coronavirus EMC 2012 (HCoV-EMC) or time-matched mock infected. Cells were harvested at 0, 3, 7, 12, 18 and 24 hours post-infection (hpi), RNA extracted and transcriptomics analyzed by microarray.
Project description:Human coronaviruses (HCoVs) cause mild to severe respiratory infection. Most of the common cold illnesses are caused by one of four HCoVs, namely HCoV-229E, HCoV-NL63, HCoV-HKU1 and HCoV-OC43. Several studies have applied global transcriptomic methods to understand host responses to HCoV infection, with most studies focusing on the pandemic severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome CoV (MERS-CoV) and the newly emerging SARS-CoV-2. In this study, Next Generation Sequencing was used to gain new insights into cellular transcriptomic changes elicited by alphacoronavirus HCoV-229E. HCoV-229E-infected MRC5 cells showed marked downregulation of superpathway of cholesterol biosynthesis and eIF2 signaling pathways. Moreover, upregulation of cyclins, cell cycle control of chromosomal replication, and role of BRCA1 in DNA damage response, alongside downregulation of the cell cycle G1/S checkpoint, suggest that HCoV-229E favors S phase for viral infection. Intriguingly, more than 80% of key factors of cell innate immunity, interferon-stimulated genes (ISGs) and other transcripts of early antiviral response genes were downregulated early in HCoV-229E infection. This study will enhance our understanding of commonly circulating HCoVs and hopefully provide critical information about still-emerging coronaviruses.
Project description:The transcription factors EB and E3 (TFEB and TFE3) promote lysosomal biogenesis and autophagy in response to a variety of stress conditions. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the ß-coronaviruses family. Recent studies have shown that ß-coronaviruses use lysosomes to egress the cell. The aim of this work is to analyze if ß-coronavirus infection promotes TFEB/3 activation and to evaluate the contribution of these transcription factors to the cellular response upon viral infection.
Project description:The transcription factors EB and E3 (TFEB and TFE3) promote lysosomal biogenesis and autophagy in response to a variety of stress conditions. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the ß-coronaviruses family. Recent studies have shown that ß-coronaviruses use lysosomes to egress the cell. The aim of this work is to analyze if ß-coronavirus infection promotes TFEB/3 activation and to evaluate the contribution of these transcription factors to the cellular response upon viral infection.
Project description:Severe acute respiratory syndrome coronavirus (SARS-CoV) causes a respiratory disease leading to death in 10% of the infected people. A mouse adapted SARS-CoV lacking the envelope (E) protein (rSARS-CoV-MA15-ΔE) is attenuated in vivo. To identify E protein domains and host responses that contribute to rSARS-CoV-MA15-ΔE attenuation, several mutants (rSARS-CoV-MA15-E*) containing point mutations or deletions in the amino-terminal or the carboxy-terminal regions of E protein, respectively, were generated. Amino acid substitutions in the amino terminus, or deletion of domains in the internal carboxy terminal region of E protein led to viral attenuation. Attenuated viruses induced minimal lung injury and limited neutrophil influx to the lungs but, interestingly, increased CD4+ and CD8+ T cell counts in BALB/c mice. To analyze the host responses leading to rSARS-CoV-MA15-E* attenuation, the differential gene expression elicited by the native virus and the mutant ones in infected cells was analyzed. The expression levels of a large number of proinflammatory cytokines inducing lung injury was reduced in the lungs of rSARS-CoV-MA15-E* infected mice, whereas the levels of anti-inflammatory cytokines were increased, both at the mRNA and protein levels. These results suggested that the reduction in lung inflammation together with a specific antiviral T cell response, contributed to rSARS-CoV-MA15-E* attenuation. Interestingly, the attenuated viruses completely protected mice against the challenge with the lethal parental virus, being promising vaccine candidates.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has killed over 6 million individuals worldwide and continues to spread in countries where vaccines are not yet widely available, or its citizens are hesitant to become vaccinated. Therefore, it is critical to unravel the molecular mechanisms that allow SARS-CoV-2 and other coronaviruses to infect and overtake the host machinery of human cells. Coronavirus replication triggers endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR), a key host cell pathway widely believed essential for viral replication. We examined the master UPR sensor IRE1a kinase/RNase and its downstream transcription factor effector XBP1s, which is processed through an IRE1a-mediated mRNA splicing event, in human lung-derived cells infected with betacoronaviruses. We found human respiratory coronavirus OC43 (HCoV-OC43), Middle East respiratory syndrome coronavirus (MERS-CoV), and murine coronavirus (MHV) all induce ER stress and strongly trigger the kinase and RNase activities of IRE1a as well as XBP1 splicing. In contrast, SARS-CoV-2 only partially activates IRE1a through autophosphorylation, but its RNase activity fails to splice XBP1. Moreover, while IRE1a was dispensable for replication in human cells for all coronaviruses tested, it was required for maximal expression of genes associated with several key cellular functions, including the interferon signaling pathway, during SARS-CoV-2 infection. Our data suggest that SARS-CoV-2 actively inhibits the RNase of autophosphorylated IRE1a, perhaps as a strategy to eliminate detection by the host immune system.