ABSTRACT
Viruses hijack host metabolic pathways for their replicative advantage. Several observational trans-omics analyses associated carbon and amino acid metabolism in coronavirus disease 2019 (COVID-19) severity in patients but lacked mechanistic insights. In this study, using patient- derived multi-omics data and in vitro infection assays, we aimed to understand i) role of key metabolic pathways in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) reproduction and ii) its association with disease severity. Our data suggests that monocytes are key to the altered immune response during COVID-19. COVID-19 infection was associated with increased plasma glutamate levels, while glucose and mannose levels were determinants of the disease severity. Monocytes showed altered expression pattern of carbohydrate and amino acid transporters, GLUT1 and xCT respectively in severe COVID-19. Furthermore, lung epithelial cells (Calu-3) showed a strong acute metabolic adaptation following infection in vitro by modulating central carbon metabolism. We found that glycolysis and glutaminolysis are essential for virus replication and blocking these metabolic pathways caused significant reduction in virus production. Taken together, our study highlights that the virus utilizes and re-wires pathways governing central carbon metabolism leading to metabolic toxicity. Thus, the host metabolic perturbation could be an attractive strategy to limit the viral replication and disease severity.
ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes Coronavirus disease 2019 (COVID-19) has caused a global health emergency. A key feature of COVID-19 is dysregulated interferon-response. Type-I interferon (IFN-I) is one of the earliest antiviral innate immune responses following viral infection and plays a significant role in the pathogenesis of SARS-CoV-2. In this study, using a proteomics-based approach, we identified that SARS-CoV-2 infection induces delayed and dysregulated IFN-I signaling in Huh7 cells. We demonstrate that SARS-CoV-2 is able to inhibit RIG-I mediated IFN-{beta} production. Our results also confirm the recent findings that IFN-I pretreatment is able to reduce susceptibility of Huh7 cells to SARS-CoV-2, but not post-treatment. Moreover, senescent Huh7 cells, in spite of showing accentuated IFN-I response were more susceptible to SARS-CoV-2 infection, and the virus effectively inhibited IFIT1 in these cells. Finally, proteomic comparison between SARS-CoV-2, SARS-CoV and MERS-CoV revealed a distinct differential regulatory signature of interferon-related proteins emphasizing that therapeutic strategies based on observations in SARS-CoV and MERS-CoV should be used with caution. Our findings provide a better understanding of SARS-CoV-2 regulation of cellular interferon response and a perspective on its use as a treatment. Investigation of different interferon stimulated genes and their role in inhibition of SARS-CoV-2 pathogenesis may direct novel antiviral strategies.
ABSTRACT
The present pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is driving intense research activities to understand the basic biology of the virus and determine effective therapeutic strategies. The commonly used laboratory cell lines of human origin are the first line of experimental models to study the pathogenicity and performing antiviral assays. Thus, to find suitable cell models to study SARS-CoV-2, we assessed the tropism and cytopathogenicity of the first Swedish isolate of SARS-CoV-2 in six different cell lines of human origin and compared their growth characteristics to other globally isolated strains. Overall, Calu-3, Caco2, Huh7, and 293FT cell lines showed a high to moderate level of susceptibility to the majority of virus isolates. In Caco2 cells the virus can achieve high titers in the absence of any prominent cytopathic effect. The protein expression profile during SARS-CoV-2 infection revealed cell-type-specific regulation of cellular pathways. Type-I interferon signaling was identified as the common dysregulated cellular response in Caco2, Calu-3 and Huh7 cells. Overall, cell-type specific variability was noted for cytopathogenicity, susceptibility and cellular response to SARS-CoV-2. This study provides important clues regarding SARS-CoV-2 pathogenesis and can represent as a guide for future studies to design therapeutics.
ABSTRACT
How Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infections engage cellular host pathways and innate immunity in infected cells remain largely elusive. We performed an integrative proteo-transcriptomics analysis in SARS-CoV-2 infected HuH7 cells to map the cellular response to the invading virus over time. We identified four pathways, ErbB, HIF-1, mTOR and TNF signaling, among others that were markedly modulated during the course of the SARS-CoV-2 infection in vitro. Western blot validation of the downstream effector molecules of these pathways revealed a significant reduction in activated S6K1 and 4E-BP1 at 72 hours post infection. Unlike other human respiratory viruses, we found a significant inhibition of HIF-1 through the entire time course of the infection, suggesting a crosstalk between the SARS-CoV-2 and the mTOR/HIF-1 signaling. Further investigations are required to better understand the molecular sequelae in order to guide potential therapy in the management of severe COVID-19 patients.
