Hepatitis C Virus Increases Free Fatty Acids Absorption and Promotes its Replication Via Down-Regulating GADD45α Expression

In vitro suppression of porcine epidemic diarrhea virus by Panax notoginseng saponins: assessing antiviral potential

Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea and high mortality in neonatal suckling piglets, leading to significant economic losses to the swine industry. Panax notoginseng saponins (PNS) are bioactive extracts derived from the P. notoginseng plant. In this study, we investigated the anti-PEDV effect of PNS by employing various methodologies to assess their impact on PEDV in Vero cells. Using a CCK-8 (Cell Counting Kit-8) assay, we found that PNS had no significant cytotoxicity below the concentration of 128 µg/mL in Vero cells. Using immunofluorescence assays (IFAs), an enzyme-linked immunosorbent assay (ELISA), and plaque formation assays, we observed a dose-dependent inhibition of PEDV infection by PNS within 24-48 hours postinfection. PNS exerts its anti-PEDV activity specifically at the genome replication stage, and mRNA-seq analysis demonstrated that treatment with PNS resulted in increased expression of various genes, including IFIT1 (interferon-induced protein with tetratricopeptide repeats 1), IFIT3 (interferon-induced protein with tetratricopeptide repeats 3), CFH (complement factor H), IGSF10 (immunoglobulin superfamily member 10), ID2 (inhibitor of DNA binding 2), SPP1 (secreted phosphoprotein 1), PLCB4 (phospholipase C beta 4), and FABP4 (fatty acid binding protein 4), but it resulted in decreased expression of IL1A (interleukin 1 alpha), TNFRSF19 (TNF receptor superfamily member 19), CDH8 (cadherin 8), DDIT3 (DNA damage inducible transcript 3), GADD45A (growth arrest and DNA damage inducible alpha), PTPRG (protein tyrosine phosphatase receptor type G), PCK2 (phosphoenolpyruvate carboxykinase 2), and ADGRA2 (adhesion G protein-coupled receptor A2). This study provides insights into the potential mechanisms underlying the antiviral effects of PNS. Taken together, the results suggest that the PNS might effectively regulate the defense response to the virus and have potential to be used in antiviral therapies.

Comparative transcriptome analysis of rainbow trout gonadal cells (RTG-2) infected with U and J genogroup infectious hematopoietic necrosis virus

Infectious hematopoietic necrosis virus (IHNV) is the causative pathogen of infectious hematopoietic necrosis, outbreaks of which are responsible for significant losses in rainbow trout aquaculture. Strains of IHNV isolated worldwide have been classified into five major genogroups, J, E, L, M, and U. To date, comparative transcriptomic analysis has only been conducted individually for the J and M genogroups. In this study, we compared the transcriptome profiles in U genogroup and J genogroup IHNV-infected RTG-2 cells with mock-infected RTG-2 cells. The RNA-seq results revealed 17,064 new genes, of which 7,390 genes were functionally annotated. Differentially expressed gene (DEG) analysis between U and J IHNV-infected cells revealed 2,238 DEGs, including 1,011 downregulated genes and 1,227 upregulated genes. Among the 2,238 DEGs, 345 new genes were discovered. The DEGs related to immune responses, cellular signal transduction, and viral diseases were further analyzed. RT-qPCR validation confirmed that the changes in expression of the immune response-related genes trpm2, sting, itgb7, ripk2, and irf1, cellular signal transduction-related genes irl, cacnb2, bmp2l, gadd45α, and plk2, and viral disease-related genes mlf1, mtor, armc5, pik3r1, and c-myc were consistent with the results of transcriptome analysis. Taken together, our findings provide a comprehensive transcriptional analysis of the differential virulence of the U and J genogroups of IHNV, and shed new light on the pathogenic mechanisms of IHNV strains.

Progress in understanding of association between metabolic associated fatty liver disease and viral infectious diseases

Metabolic associated fatty liver disease (MAFLD) is a chronic liver disease with the highest incidence in the world, which affects 1/4-1/3 of the world population and has a serious effect on people's health. As is a multi-systemic disease, MAFLD is closely related to the occurrence and prognosis of many diseases. Studies have shown that MAFLD is associated with viral infectious diseases, and their interaction affects the prognosis of the disease. This paper reviews the research progress in this field in recent years.

The Impact of Steatosis on Chronic Hepatitis C Progression and Response to Antiviral Treatments

Metabolic derangement is characteristic in patients with hepatitis C virus (HCV) infection. Aside from established liver injury, various extrahepatic metabolic disorders impact the natural history of the disease, clinical outcomes, and the efficacy of antiviral therapy. The presence of steatosis, recently redefined as metabolic-associated fatty liver disease (MAFLD), is a common feature in HCV-infected patients, induced by host and/or viral factors. Most chronic HCV-infected (CHC) patients have mild steatosis within the periportal region of the liver with an estimated prevalence of 40% to 86%. Indeed, this is higher than the 19% to 50% prevalence observed in patients with other chronic liver diseases such as chronic hepatitis B (CHB). The histological manifestations of HCV infection are frequently observed in genotype 3 (G-3), where relative to other genotypes, the prevalence and severity of steatosis is also increased. Steatosis may independently influence the treatment efficacy of either interferon-based or interferon-free antiviral regimens. This review aimed to provide updated evidence of the prevalence and risk factors behind HCV-associated steatosis, as well as explore the impact of steatosis on HCV-related outcomes.

Morphological cell profiling of SARS-CoV-2 infection identifies drug repurposing candidates for COVID-19

Since its emergence in China in December 2019, SARS-CoV-2 has caused a global pandemic. Repurposing of FDA-approved drugs is a promising strategy for identifying rapidly deployable treatments for COVID-19. Herein, we developed a pipeline for quantitative, high-throughput, image-based screening of SARS-CoV-2 infection in human cells that led to the identification of several FDA-approved drugs and clinical candidates with in vitro antiviral activity.

The global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated disease COVID-19, requires therapeutic interventions that can be rapidly identified and translated to clinical care. Traditional drug discovery methods have a >90% failure rate and can take 10 to 15 y from target identification to clinical use. In contrast, drug repurposing can significantly accelerate translation. We developed a quantitative high-throughput screen to identify efficacious agents against SARS-CoV-2. From a library of 1,425 US Food and Drug Administration (FDA)-approved compounds and clinical candidates, we identified 17 hits that inhibited SARS-CoV-2 infection and analyzed their antiviral activity across multiple cell lines, including lymph node carcinoma of the prostate (LNCaP) cells and a physiologically relevant model of alveolar epithelial type 2 cells (iAEC2s). Additionally, we found that inhibitors of the Ras/Raf/MEK/ERK signaling pathway exacerbate SARS-CoV-2 infection in vitro. Notably, we discovered that lactoferrin, a glycoprotein found in secretory fluids including mammalian milk, inhibits SARS-CoV-2 infection in the nanomolar range in all cell models with multiple modes of action, including blockage of virus attachment to cellular heparan sulfate and enhancement of interferon responses. Given its safety profile, lactoferrin is a readily translatable therapeutic option for the management of COVID-19.

Alteration in the Lipid Profile and the Desaturases Activity in Patients With Severe Pneumonia by SARS-CoV-2

The kidnapping of the lipid metabolism of the host's cells by severe acute respiratory syndrome (SARS-CoV-2) allows the virus to transform the cells into optimal machines for its assembly and replication. Here we evaluated changes in the fatty acid (FA) profile and the participation of the activity of the desaturases, in plasma of patients with severe pneumonia by SARS-CoV-2. We found that SARS-CoV-2 alters the FA metabolism in the cells of the host. Changes are characterized by variations in the desaturases that lead to a decrease in total fatty acid (TFA), phospholipids (PL) and non-esterified fatty acids (NEFAs). These alterations include a decrease in palmitic and stearic acids (p ≤ 0.009) which could be used for the formation of the viral membranes and for the reparation of the host's own membrane. There is also an increase in oleic acid (OA; p = 0.001) which could modulate the inflammatory process, the cytokine release, apoptosis, necrosis, oxidative stress (OS). An increase in linoleic acid (LA) in TFA (p = 0.03) and a decreased in PL (p = 0.001) was also present. They result from damage of the internal mitochondrial membrane. The arachidonic acid (AA) percentage was elevated (p = 0.02) in the TFA and this can be participated in the inflammatory process. EPA was decreased (p = 0.001) and this may decrease of pro-resolving mediators with increase in the inflammatory process. The total of NEFAs (p = 0.03), PL (p = 0.001), cholesterol, HDL and LDL were decreased, and triglycerides were increased in plasma of the COVID-19 patients. Therefore, SARS-CoV-2 alters the FA metabolism, the changes are characterized by alterations in the desaturases that lead to variations in the TFA, PL, and NEFAs profiles. These changes may favor the replication of the virus but, at the same time, they are part of the defense system provided by the host cell metabolism in its eagerness to repair damage caused by the virus to cell membranes.

Metabolic profiling of fatty acids in Tripterygium wilfordii multiglucoside- and triptolide-induced liver-injured rats

Tripterygium wilfordii multiglucoside (TWM) is a fat-soluble extract from a Chinese herb T. wilfordii, that’s used in treating rheumatoid arthritis, nephrotic syndrome and other skin diseases. Triptolide (TP) is a major active component in TWM. However, clinical applications of TWM are limited by its various toxicities especially hepatotoxicity. In recent studies, it has been reported that drug-induced liver injury (DILI) could induce the disorder of lipid metabolism in animals. Hence, this study focuses on the metabolic profile of fatty acids in TWM- and TP-induced liver-injured rats. In serum and liver tissue, 16 free and 16 esterified fatty acids were measured by gas chromatography coupled with mass spectrometry. Metabolic profile of serum fatty acids in rats with liver injury was identified by multivariate statistical analysis. The fatty acid levels in the serum of TWM- and TP-treated rats significantly decreased, whereas those in the liver tissue of TWM- and TP-treated rats obviously increased when compared with the vehicle-treated rats. Four free fatty acids were identified as candidate biomarkers of TWM- and TP-induced liver injury. Therefore, the targeted metabolomic method may be used as a complementary approach for DILI diagnosis in clinic.

Morphological Cell Profiling of SARS-CoV-2 Infection Identifies Drug Repurposing Candidates for COVID-19

The global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated disease COVID-19, requires therapeutic interventions that can be rapidly identified and translated to clinical care. Traditional drug discovery methods have a >90% failure rate and can take 10–15 years from target identification to clinical use. In contrast, drug repurposing can significantly accelerate translation. We developed a quantitative high-throughput screen to identify efficacious agents against SARS-CoV-2. From a library of 1,425 FDA-approved compounds and clinical candidates, we identified 17 dose-responsive compounds with in vitro antiviral efficacy in human liver Huh7 cells and confirmed antiviral efficacy in human colon carcinoma Caco-2, human prostate adenocarcinoma LNCaP, and in a physiologic relevant model of alveolar epithelial type 2 cells (iAEC2s). Additionally, we found that inhibitors of the Ras/Raf/MEK/ERK signaling pathway exacerbate SARS-CoV-2 infection in vitro. Notably, we discovered that lactoferrin, a glycoprotein classically found in secretory fluids, including mammalian milk, inhibits SARS-CoV-2 infection in the nanomolar range in all cell models with multiple modes of action, including blockage of virus attachment to cellular heparan sulfate and enhancement of interferon responses. Given its safety profile, lactoferrin is a readily translatable therapeutic option for the management of COVID-19.

USP15 Participates in Hepatitis C Virus Propagation through Regulation of Viral RNA Translation and Lipid Droplet Formation

Hepatitis C virus (HCV) utilizes cellular factors for efficient propagation. Ubiquitin is covalently conjugated to the substrate to alter its stability or to modulate signal transduction. In this study, we examined the importance of ubiquitination for HCV propagation. We found that inhibition of deubiquitinating enzymes (DUBs) or overexpression of nonspecific DUBs impaired HCV replication, suggesting that ubiquitination regulates HCV replication. To identify specific DUBs involved in HCV propagation, we set up RNA interference (RNAi) screening against DUBs and successfully identified ubiquitin-specific protease 15 (USP15) as a novel host factor for HCV propagation. Our studies showed that USP15 is involved in translation of HCV RNA and production of infectious HCV particles. In addition, deficiency of USP15 in human hepatic cell lines (Huh7 and Hep3B/miR-122 cells) but not in a nonhepatic cell line (293T cells) impaired HCV propagation, suggesting that USP15 participates in HCV propagation through the regulation of hepatocyte-specific functions. Moreover, we showed that loss of USP15 had no effect on innate immune responses in vitro and in vivo We also found that USP15-deficient Huh7 cells showed reductions in the amounts of lipid droplets (LDs), and the addition of palmitic acids restored the production of infectious HCV particles. Taken together, these data suggest that USP15 participates in HCV propagation by regulating the translation of HCV RNA and the formation of LDs.IMPORTANCE Although ubiquitination has been shown to play important roles in the HCV life cycle, the roles of deubiquitinating enzymes (DUBs), which cleave ubiquitin chains from their substrates, in HCV propagation have not been investigated. Here, we identified USP15 as a DUB regulating HCV propagation. USP15 showed no interaction with viral proteins and no participation in innate immune responses. Deficiency of USP15 in Huh7 cells resulted in suppression of the translation of HCV RNA and reduction in the amounts of lipid droplets, and the addition of fatty acids partially restored the production of infectious HCV particles. These data suggest that USP15 participates in HCV propagation in hepatic cells through the regulation of viral RNA translation and lipid metabolism.