ABSTRACT: SARS-CoV-2 pandemic has caused a dramatic health, social and economic crisis worldwide. To better understand the host-virus interactions and identify potentially targetable host factors, we have conducted CRISPR-Cas9 genetic screens using SARS-CoV-2 pseudotyped lentiviruses on human lung cancer cells. Our results recapitulate many findings from previous screens that used full SARS-CoV-2 viruses, but also unveil two novel critical host factors: SPNS1 and PLAC8. Functional experiments with full SARS-CoV-2 viruses have confirmed that loss-of-function of these genes impairs viral entry. Importantly, we have found that PLAC8 is a key limiting host factor whose overexpression boosts viral infection in eight different human lung cancer cell lines. Using single-cell RNA-Seq data analyses, we demonstrate that PLAC8 is highly expressed in ciliated and secretory cells from the respiratory tract and in gut enterocytes, cell types that are highly susceptible to SARS-CoV-2 infection. Finally, proteomics and cell biology studies suggest that SPNS1 and PLAC8 affect viral entry through regulation of autophagy and lysosomal function.
Project description:We performed genome-wide CRISPR KO screens in human Huh7.5.1 cells to select for mutations that render host cells resistant to viral infection by SARS-CoV-2, human coronavirus 229E and OC43.
Project description:The coronavirus disease 2019 (COVID-19) has caused over 6 million deaths worldwide and disrupted the global economy. The causative agent for this disease, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes mild to lethal respiratory infections. Understanding the cellular host factors that promote and inhibit for SARS-CoV-2 infection is important for identifying virial countermeasures. Moreover, new methods are needed to be to identify host genes influencing specific steps of viral infections. Here, we developed a CRISPR whole genome screen against SARS-CoV-2 spike enveloped retro-pseudoviruses with a GFP reporter to specifically identify host genes that facilitate viral entry. By including two counter screen strategies, this approach can be used to distinguish host genes affecting the pseudoviral reporter from those unique to envelope-mediated entry. First, an alternate envelope, VSV-G allowed identification of shared genes associated with retro-transcription, integration and reporter expression. Second, a recently developed Cre-Gag fusion pseudovirus bypassed retro transcription and integration by directly activating a floxed GFP reporter. Our approach correctly identified SARS-CoV-2 and VSV-G receptors ACE2 and LDLR, respectively and distinguished genes associated with retroviral reporter expression from envelope mediated entry. Overall, this work provides a new strategy for screening genes influencing envelope mediated entry without the complexity of live-viral screens which are complicated with large numbers of genes associated with all aspects of viral pathogenesis and replication. This approach should be of use for identifying genes contributing to and inhibiting SARS-CoV-2 entry and provide a platform for the analysis of newly emerging viruses.
Project description:Several genome-wide CRISPR knockout screens have been conducted to identify host factors regulating SARS-CoV-2 replication, but the models used have often relied on overexpression of ACE2 receptor and didn’t express TMPRSS2 protease, known to be important for viral entry at the plasma membrane. Here, we conducted a meta-analysis of these screens and showed a high level of cell-type specificity of the identified hits, arguing for the necessity to pursue efforts to uncover the full landscape of SARS-CoV-2 regulators. We performed genome-wide, bidirectional CRISPR screens in Calu-3 lung epithelial cells, as well as knockout screens in Caco-2 intestinal cells. As well as identifying ACE2 and TMPRSS2 as top hits, our study reveals a series of so far unidentified and critical host-dependency factors, including the Adaptins AP1G1 and AP1B1 and the flippase ATP8B1. Additionally, new anti-SARS-CoV-2 proteins with potent activity, including several membrane-associated Mucins (MUC1, MUC4 and MUC21), IL6R and CD44 were identified . We further observed that these genes mostly acted at the critical step of viral entry, with the notable exception of ATP8B1, the knockout of which prevented late stages of viral replication. Exploring the pro- and anti-viral breadth of these genes using highly pathogenic MERS-CoV, seasonal HCoV-NL63 and -229E and influenza A virus, we reveal that some genes such as AP1G1 and ATP8B1 are general coronavirus cofactors. In contrast, Mucins recapitulated their known role as a general antiviral defense mechanism. These results demonstrate the value of considering multiple cell models and perturbational modalities for understanding SARS-CoV-2 replication and provide a list of potential new targets for therapeutic interventions.
Project description:Several genome-wide CRISPR knockout screens have been conducted to identify host factors regulating SARS-CoV-2 replication, but the models used have often relied on overexpression of ACE2 receptor and didn’t express TMPRSS2 protease, known to be important for viral entry at the plasma membrane. Here, we conducted a meta-analysis of these screens and showed a high level of cell-type specificity of the identified hits, arguing for the necessity to pursue efforts to uncover the full landscape of SARS-CoV-2 regulators. We performed genome-wide, bidirectional CRISPR screens in Calu-3 lung epithelial cells, as well as knockout screens in Caco-2 intestinal cells. As well as identifying ACE2 and TMPRSS2 as top hits, our study reveals a series of so far unidentified and critical host-dependency factors, including the Adaptins AP1G1 and AP1B1 and the flippase ATP8B1. Additionally, new anti-SARS-CoV-2 proteins with potent activity, including several membrane-associated Mucins (MUC1, MUC4 and MUC21), IL6R and CD44 were identified . We further observed that these genes mostly acted at the critical step of viral entry, with the notable exception of ATP8B1, the knockout of which prevented late stages of viral replication. Exploring the pro- and anti-viral breadth of these genes using highly pathogenic MERS-CoV, seasonal HCoV-NL63 and -229E and influenza A virus, we reveal that some genes such as AP1G1 and ATP8B1 are general coronavirus cofactors. In contrast, Mucins recapitulated their known role as a general antiviral defense mechanism. These results demonstrate the value of considering multiple cell models and perturbational modalities for understanding SARS-CoV-2 replication and provide a list of potential new targets for therapeutic interventions.
Project description:Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) are zoonotic pathogens that can cause severe respiratory disease in humans. Identification of the host factors that are necessary for viral infection and virus-induced cell death is critical to our understanding of the viral life cycle and can potentially aid the development of new treatment options. Here, we report CRISPR screen results of both SARS-CoV and MERS-CoV infections in derivatives of the human hepatoma cell line Huh7. Our screens identified the known entry receptors ACE2 for SARS-CoV and DPP4 for MERS-CoV. Additionally, the SARS-CoV screen uncovered several components of the NF-κB signaling pathway (CARD10, BCL10, MALT1, MAP3K7, IKBKG), while the MERS-CoV screen revealed the polypyrimidine tract-binding protein PTBP1, the ER scramblase TMEM41B, furin protease and several transcriptional and chromatin regulators as candidate factors for viral replication and/or virus-induced cell death. Together, we present several known and unknown coronavirus host factors that are of interest for further investigation.
Project description:The global spread of SARS-CoV-2 lead to the most challenging pandemic in this century, posing major economic and health challenges worldwide. Revealing host genes essential for infection by multiple variants of SARS-CoV-2 can provide insights into the virus pathogenesis, and facilitates the development of novel broad-spectrum host-directed therapeutics. Here, employing genome-scale CRISPR screens, we provide a comprehensive data-set of cellular factors that are exploited by WT-SARS-CoV-2 as well as two additional recently emerged variants of concerns (VOCs), Alpha and Beta. These screens identified known and novel host factors critical for SARS-CoV-2 infection, including various components belonging to the Clathrin-dependent transport pathway, ubiquitination and Heparan sulfate biogenesis. In addition, the host phosphatidylglycerol biosynthesis processes appeared to have major anti-viral functions. Comparative analysis of the different VOCs revealed the host factors KREMEN2 and SETDB1 as potential unique candidates required only to the Alpha variant, providing a possible explanation for the increased infectivity of this variant. Furthermore, the analysis identified GATA6, a zinc finger transcription factor, as an essential pro-viral gene for all variants inspected. We revealed that GATA6 directly regulates ACE2 transcription and accordingly, is critical for SARS-CoV-2 cell entry. Analysis of clinical samples collected from SARS-CoV-2 infected individuals showed an elevated level of GATA6, indicating the important role GATA6 may be playing in COVID-19 pathogenesis. Finally, pharmacological inhibition of GATA6 resulted in down-modulation of ACE2 and consequently to inhibition of the viral infectivity. Overall, we show GATA6 represents a target for the development of anti-SARS-CoV-2 therapeutic strategies and reaffirm the value of the CRISPR loss-of-function screens in providing a list of potential new targets for therapeutic interventions.
Project description:SARS-CoV-2 depends on host cell components for replication, therefore the identification of virus-host dependencies offers an effective way to elucidate mechanisms involved in viral infection. Such host factors may be necessary for infection and replication of SARS-CoV-2 and, if druggable, presents an attractive strategy for anti-viral therapy. We performed genome-wide CRISPR knockout screens in Vero E6 cells and 4 human cell lines including Calu-3, Caco-2, Hek293 and Huh7 to identify genetic regulators of SARS-CoV-2 infection. Our findings identified only ACE2, the cognate SARS-CoV-2 entry receptor, as a common host dependency factor across all cell lines, while all other host genes identified were cell line-specific, including known factors TMPRSS2 and CTSL. Several of the discovered host-dependency factors converged on pathways involved in cell signalling, lipid metabolism, immune pathways and chromatin modulation. Notably, chromatin modulator genes KMT2C and KDM6A in Calu-3 cells had the strongest impact in preventing SARS-CoV-2 infection when perturbed. Overall, the network of host factors that have been identified will be broadly applicable to understanding the impact of SARS-CoV-2 on human cells and facilitate the development of host-directed therapies.
Project description:Viruses hijack host cell metabolism to acquire the building blocks required for viral replication. Understanding how SARS-CoV-2 alters host cell metabolism could lead to potential treatments for COVID-19, the disease caused by SARS-CoV-2 infection. Here we profile metabolic changes conferred by SARS-CoV-2 infection in kidney epithelial cells and lung air-liquid interface cultures and show that SARS-CoV-2 infection increases glucose carbon entry into the TCA cycle via increased pyruvate carboxylase expression. SARS-CoV-2 also reduces host cell oxidative glutamine metabolism while maintaining reductive carboxylation. Consistent with these changes in host cell metabolism, we show that SARS-CoV-2 increases activity of mTORC1, a master regulator of anabolic metabolism, in cell lines and patient lung stem cell-derived airway epithelial cells. We also show evidence of mTORC1 activation in COVID-19 patient lung tissue. Notably, mTORC1 inhibitors reduce viral replication in kidney epithelial cells and patient-derived lung stem cell cultures. This suggests that targeting mTORC1 could be a useful antiviral strategy for SARS-CoV-2 and treatment strategy for COVID-19 patients, although further studies are required to determine the mechanism of inhibition and potential efficacy in patients.
Project description:In a screen of human upper airway cell lines, we identified the H522 lung adenocarcinoma cells as naturally permissive to SARS-CoV-2 infection despite no evidence of ACE2 or TMPRSS2 expression. Temporally resolved transcriptomic and proteomic profiling of H522 cells revealed consistent alterations in the antiviral host cell response, including marked activation of type-I interferon signaling. Focused chemical screens point to important roles for clathrin-mediated endocytosis and endosomal cathepsins in SARS-CoV-2 infection of H522 cells. The natural permissiveness of H522 cells to SARS-CoV-2 infection despite no requirement for ACE2 implies the utilization of an alternative receptor and viral entry mechanism which may have important implications for SARS-CoV-2 pathogenesis in humans.
Project description:The severe acute respiratory syndrome (SARS) epidemic was characterized by increased pathogenicity in the elderly due to an early exacerbated innate host response. SARS-CoV is a zoonotic pathogen that entered the human population through an intermediate host like the palm civet. To prevent future introductions of zoonotic SARS-CoV strains and subsequent transmission into the human population, heterologous disease models are needed to test the efficacy of vaccines and therapeutics against both late human and zoonotic isolates. Here we show that both human and zoonotic SARS-CoV strains can infect cynomolgus macaques and resulted in radiological as well as histopathological changes similar to those seen in mild human cases. Viral replication was higher in animals infected with a late human phase isolate compared to a zoonotic isolate. Host responses to the three SARS-CoV strains were similar and only apparent early during infection with the majority of genes associated with interferon signalling pathways.This study characterizes critical disease models in the evaluation and licensure of therapeutic strategies against SARS-CoV for human use 4 strains, time course, lungs