Hepatitis C virus hijacks host lipid metabolism

ACADM inhibits AMPK activation to modulate PEDV-induced lipophagy and β-oxidation for impairing viral replication

Porcine epidemic diarrhea virus (PEDV) belongs to the Alphacoronavirus genus within the Coronavirus family, causing severe watery diarrhea in piglets and resulting in significant economic losses. Medium-chain acyl-CoA dehydrogenase (ACADM) is an enzyme participating in lipid metabolism associated with metabolic diseases and pathogen infections. Nonetheless, the precise role of ACADM in regulating PEDV replication remains uncertain. In this study, we identified ACADM as the host binding partner of NSP4 via immunoprecipitation-mass spectrometry analysis. The interaction between ACADM and NSP4 was subsequently corroborated through coimmunoprecipitation and laser confocal microscopy. Following this, a notable upsurge in ACADM expression was observed during PEDV infection. ACADM overexpression effectively inhibited virus replication, whereas ACADM knockdown facilitated virus replication, suggesting ACADM has negative regulation effect on PEDV infection. Furthermore, we demonstrated fatty acid β-oxidation affected PEDV replication for the first time, inhibition of fatty acid β-oxidation reduced PEDV replication. ACADM decreased PEDV-induced β-oxidation to suppress PEDV replication. Mechanistically, ACADM reduced cellular free fatty acid levels and subsequent β-oxidation by hindering AMPK-mediated lipophagy. In summary, our results reveal that ACADM plays a negative regulatory role in PEDV replication by regulating lipid metabolism. The present study introduces a novel approach for the prevention and control of PEDV infection.

HDL-based therapeutics: A promising frontier in combating viral and bacterial infections

Low levels of high-density lipoprotein (HDL) and impaired HDL functionality have been consistently associated with increased susceptibility to infection and its serious consequences. This has been attributed to the critical role of HDL in maintaining cellular lipid homeostasis, which is essential for the proper functioning of immune and structural cells. HDL, a multifunctional particle, exerts pleiotropic effects in host defense against pathogens. It functions as a natural nanoparticle, capable of sequestering and neutralizing potentially harmful substances like bacterial lipopolysaccharides. HDL possesses antiviral activity, preventing viruses from entering or fusing with host cells, thereby halting their replication cycle. Understanding the complex relationship between HDL and the immune system may reveal innovative targets for developing new treatments to combat infectious diseases and improve patient outcomes. This review aims to emphasize the role of HDL in influencing the course of bacterial and viral infections and its and its therapeutic potential.

Norovirus NS1/2 protein increases glutaminolysis for efficient viral replication

Viruses are obligate intracellular parasites that rely on host cell metabolism for successful replication. Thus, viruses rewire host cell pathways involved in central carbon metabolism to increase the availability of building blocks for successful propagation. However, the underlying mechanisms of virus-induced alterations to host metabolism are largely unknown. Noroviruses (NoVs) are highly prevalent pathogens that cause sporadic and epidemic viral gastroenteritis. In the present study, we uncovered several strain-specific and shared host cell metabolic requirements of three murine norovirus (MNV) strains, MNV-1, CR3, and CR6. While all three strains required glycolysis, glutaminolysis, and the pentose phosphate pathway for optimal infection of macrophages, only MNV-1 relied on host oxidative phosphorylation. Furthermore, the first metabolic flux analysis of NoV-infected cells revealed that both glycolysis and glutaminolysis are upregulated during MNV-1 infection of macrophages. Glutamine deprivation affected the viral lifecycle at the stage of genome replication, resulting in decreased non-structural and structural protein synthesis, viral assembly, and egress. Mechanistic studies further showed that MNV infection and overexpression of the non-structural protein NS1/2 increased the enzymatic activity of the rate-limiting enzyme glutaminase. In conclusion, the inaugural investigation of NoV-induced alterations to host glutaminolysis identified NS1/2 as the first viral molecule for RNA viruses that regulates glutaminolysis either directly or indirectly. This increases our fundamental understanding of virus-induced metabolic alterations and may lead to improvements in the cultivation of human NoVs.

A multicellular liver organoid model for investigating hepatitis C virus infection and nonalcoholic fatty liver disease progression

BACKGROUND AND AIMS

HCV infection can be successfully managed with antiviral therapies; however, progression to chronic liver disease states, including NAFLD, is common. There is currently no reliable in vitro model for investigating host-viral interactions underlying the link between HCV and NAFLD; although liver organoids (LOs) show promise, they currently lack nonparenchymal cells, which are key to modeling disease progression.

APPROACH AND RESULTS

Here, we present a novel, multicellular LO model using a coculture system of macrophages and LOs differentiated from the same human pluripotent stem cells (PSCs). The cocultured macrophages shifted toward a Kupffer-like cell type, the liver-resident macrophages present in vivo , providing a suitable model for investigating NAFLD pathogenesis. With this multicellular Kupffer-like cell-containing LO model, we found that HCV infection led to lipid accumulation in LOs by upregulating host lipogenesis, which was more marked with macrophage coculture. Reciprocally, long-term treatment of LOs with fatty acids upregulated HCV amplification and promoted inflammation and fibrosis. Notably, in our Kupffer-like cell-containing LO model, the effects of 3 drugs for NASH that have reached phase 3 clinical trials exhibited consistent results with the clinical outcomes.

CONCLUSIONS

Taken together, we introduced a multicellular LO model consisting of hepatocytes, Kupffer-like cells, and HSCs, which recapitulated host-virus intercommunication and intercellular interactions. With this novel model, we present a physiologically relevant system for the investigation of NAFLD progression in patients with HCV.

Unveiling Actin Cytoskeleton Role in Mediating Chikungunya-Associated Arthritis: An Integrative Proteome-Metabolome Study

Background: Chikungunya is a zoonotic disease caused by the Chikungunya virus (CHIKV), primarily transmitted to humans through infected Aedes mosquitoes. The infection is characterized by symptoms such as high fever, musculoskeletal pain, polyarthritis, and a rash, which can lead to severe complications such as encephalitis, meningitis, and even fatalities. While many disease manifestations resemble those of other viral infections, chronic arthritis caused by CHIKV is unique, and its molecular mechanisms remain ill-defined. Materials and Methods: Proteomics data from both cellular and patient levels of CHIKV infection were curated from PubMed and screened using inclusion and exclusion criteria. Patient serum proteomics data obtained from P RIDE underwent reanalysis using Proteome Discoverer 2.2. Enrichment and protein-protein interaction network analysis were conducted on differentially expressed proteins from both serum and cellular datasets. Metabolite data from CHIKV-infected patients were further retrieved, and their protein binding partners were identified using BindingDB. The protein-metabolite interaction pathway was further developed using MetaboAnalyst. Results: The proteomics data analysis revealed differential expression of proteins involved in critical host mechanisms, such as cholesterol metabolism and mRNA splicing, during CHIKV infection. Consistent upregulation of two actin cytoskeleton proteins, TAGLN2 and PFN1, was noted in both serum and cellular datasets, and their upregulations are associated with arthritis. Furthermore, alterations in purine metabolism were observed in the integrative proteome-metabolome analysis, correlating with cytoskeletal remodelling. Conclusion: Collectively, this integrative view sheds light on the involvement of actin cytoskeleton remodeling proteins and purine metabolic pathways in the development of arthritis during CHIKV infection.

Effect of HCV eradication by DAAs on liver steatosis, carotid atherosclerosis, and associated metabolic comorbidities: A systematic review

BACKGROUND AND AIMS

The beneficial effect of Hepatitis C virus (HCV) eradication by direct antiviral agents (DAAs) on liver fibrosis is well defined. Despite this, the impact of viral eradication in both hepatic and extra-hepatic metabolic features is underreached. This systematic review aimed to synthesize the evidence on the impact of HCV eradication by DAAs on liver steatosis, carotid atherosclerosis, glucidic impairment, dyslipidaemia, and weight gain.

METHODS

A systematic search of the existing literature (up to December 2022) identified 97 original studies that fulfilled the inclusion criteria.

RESULTS

Whereas total cholesterol and low-density lipoprotein (LDL) seem to increase after viral eradication, the cardiovascular damage expressed as carotid plaques and intima-media thickness seems to improve. Otherwise, the effect on liver steatosis, glucidic homeostasis, and weight seems to be strictly dependent on the presence of baseline metabolic disorders.

CONCLUSION

Despite high heterogeneity and relatively short follow-up of included studies, we can conclude that the presence of metabolic risk factors should be strictly evaluated due to their impact on liver steatosis, glucidic and lipid homeostasis, and on weight gain to better identify patients at risk of liver disease progression despite the virus eradication.

Role of aryl hydrocarbon receptors in infection and inflammation

The aryl hydrocarbon receptor (AhR) is a transcription factor that is activated by various ligands, including pollutants, microorganisms, and metabolic substances. It is expressed extensively in pulmonary and intestinal epithelial cells, where it contributes to barrier defense. The expression of AhR is pivotal in regulating the inflammatory response to microorganisms. However, dysregulated AhR expression can result in endocrine disorders, leading to immunotoxicity and potentially promoting the development of carcinoma. This review focuses on the crucial role of the AhR in facilitating and limiting the proliferation of pathogens, specifically in relation to the host cell type and the species of etiological agents involved in microbial pathogen infections. The activation of AhR is enhanced through the IDO1-AhR-IDO1 positive feedback loop, which is manipulated by viruses. AhR primarily promotes the infection of SARS-CoV-2 by inducing the expression of angiotensin-converting enzyme 2 (ACE2) and the secretion of pro-inflammatory cytokines. AhR also plays a significant role in regulating various types of T-cells, including CD4+ T cells and CD8+ T cells, in the context of pulmonary infections. The AhR pathway plays a crucial role in regulating immune responses within the respiratory and intestinal barriers when they are invaded by viruses, bacteria, parasites, and fungi. Additionally, we propose that targeting the agonist and antagonist of AhR signaling pathways could serve as a promising therapeutic approach for combating pathogen infections, especially in light of the growing prevalence of drug resistance to multiple antibiotics.

Effects of sustained viral response on lipid in Hepatitis C: a systematic review and meta-analysis

BACKGROUND

Direct-acting Antiviral Agents (DAAs) influence serum lipids of patients with Hepatitis C virus (HCV). This paper presents an analysis of the relevant literature to investigate the effects of DAAs in treating hepatitis C to achieve a sustained viral response (SVR) on lipid parameters.

METHODS

PubMed,Web of science, Embase and Central databases were searched, with a deadline of September 2023. Studies on the effects of sustained viral response on lipid parameters after DAAs treatment for hepatitis C were selected. The required information was extracted from the included studies, and then the Stata 12.0 was used to analyze the data quantitatively.

RESULTS

Of 32 studies, the results showed that total cholesterol (TC) levels increased from the end of treatment (WMD = 20.144, 95%CI = 3.404, 36.884,P = 0.018) to one year after treatment (WMD = 24.900, 95%CI = 13.669, 36.131, P < 0.001). From the end of treatment (WMD = 17.728, 95%CI = 4.375, 31.082, P = 0.009) to one year after treatment (WMD = 18.528, 95%CI = 7.622, 29.433, P < 0.001), the levels of low-density lipoprotein (LDL) were also increased. High-density lipoprotein (HDL) levels were elevated from 4 weeks after treatment (WMD = 6.665, 95%CI = 3.906, 9.424, P < 0.001) to 24 weeks after treatment (WMD = 3.159,95% CI = 0.176, 6.142, P = 0.038). Triglyceride (TG) levels showed no significant change after the treatment.

CONCLUSIONS

Hepatitis C patients who achieved SVR on DAAs showed the increase of lipid levels and the improvement of hepatic inflammation indicators AST and ALT. This may provide evidence-based medical evidence for the follow-up and monitoring of blood lipids and hyperlipidemia treatment.

REGISTRATION

PROSPERO CRD42020180793.

Pralatrexate inhibited the replication of varicella zoster virus and vesicular stomatitis virus: An old dog with new tricks

Varicella zoster virus (VZV) is associated with herpes zoster (HZ) or herpes zoster ophthalmicus (HZO). All antiviral agents currently licensed for the management of VZV replication via modulating different mechanisms, and the resistance is on the rise. There is a need to develop new antiviral agents with distinct mechanisms of action and adequate safety profiles. Pralatrexate (PDX) is a fourth-generation anti-folate agent with an inhibitory activity on folate (FA) metabolism and has been used as an anti-tumor drug. We observed that PDX possessed potent inhibitory activity against VZV infection. In this study, we reported the antiviral effects and the underlying mechanism of PDX against VZV infection. The results showed that PDX not only inhibited VZV replication in vitro and in mice corneal tissues but also reduced the inflammatory response and apoptosis induced by viral infection. Furthermore, PDX treatment showed a similar anti-VSV inhibitory effect in both in vitro and in vivo models. Mechanistically, PDX inhibited viral replication by interrupting the substrate supply for de novo purine and thymidine synthesis. In conclusion, this study discovered the potent antiviral activity of PDX with a novel mechanism and presented a new strategy for VZV treatment that targets a cellular metabolic mechanism essential for viral replication. The present study provided a new insight into the development of broad-spectrum antiviral agents.

Norovirus NS1/2 protein increases glutaminolysis for efficient viral replication

Viruses are obligate intracellular parasites that rely on host cell metabolism for successful replication. Thus, viruses rewire host cell pathways involved in central carbon metabolism to increase the availability of building blocks for replication. However, the underlying mechanisms of virus-induced alterations to host metabolism are largely unknown. Noroviruses (NoVs) are highly prevalent pathogens that cause sporadic and epidemic viral gastroenteritis. In the present study, we uncovered several strain-specific and shared host cell metabolic requirements of three murine norovirus (MNV) strains, the acute MNV-1 strain and the persistent CR3 and CR6 strains. While all three strains required glycolysis, glutaminolysis, and the pentose phosphate pathway for optimal infection of macrophages, only MNV-1 relied on host oxidative phosphorylation. Furthermore, the first metabolic flux analysis of NoV-infected cells revealed that both glycolysis and glutaminolysis are upregulated during MNV-1 infection of macrophages. Glutamine deprivation affected the MNV lifecycle at the stage of genome replication, resulting in decreased non-structural and structural protein synthesis, viral assembly, and egress. Mechanistic studies further showed that MNV infection and overexpression of the MNV non-structural protein NS1/2 increased the enzymatic activity of the rate-limiting enzyme glutaminase. In conclusion, the inaugural investigation of NoV-induced alterations to host glutaminolysis identified the first viral regulator of glutaminolysis for RNA viruses, which increases our fundamental understanding of virus-induced metabolic alterations.

Inhibition of the SREBP pathway prevents SARS-CoV-2 replication and inflammasome activation

SARS-CoV-2 induces major cellular lipid rearrangements, exploiting the host's metabolic pathways to replicate. Sterol regulatory element binding proteins (SREBPs) are a family of transcription factors that control lipid metabolism. SREBP1 is associated with the regulation of fatty acids, whereas SREBP2 controls cholesterol metabolism, and both isoforms are associated with lipid droplet (LD) biogenesis. Here, we evaluated the effect of SREBP in a SARS-CoV-2-infected lung epithelial cell line (Calu-3). We showed that SARS-CoV-2 infection induced the activation of SREBP1 and SREBP2 and LD accumulation. Genetic knockdown of both SREBPs and pharmacological inhibition with the dual SREBP activation inhibitor fatostatin promote the inhibition of SARS-CoV-2 replication, cell death, and LD formation in Calu-3 cells. In addition, we demonstrated that SARS-CoV-2 induced inflammasome-dependent cell death by pyroptosis and release of IL-1β and IL-18, with activation of caspase-1, cleavage of gasdermin D1, was also reduced by SREBP inhibition. Collectively, our findings help to elucidate that SREBPs are crucial host factors required for viral replication and pathogenesis. These results indicate that SREBP is a host target for the development of antiviral strategies.

Diagnosis and monitoring of hepatocellular carcinoma in Hepatitis C virus patients using attenuated total reflection Fourier transform infrared spectroscopy

BACKGROUND

Current diagnostic methods for assessment of hepatitis C virus related hepatocellular carcinoma and subsequent categorization of hepatocellular carcinoma into non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma, to establish appropriate treatment strategies, are costly, invasive and requires multiple screening steps. This demands alternative diagnostic approaches that are cost-effective, time-efficient, and minimally invasive, while maintaining their efficacy for screening of hepatitis c virus related hepatocellular carcinoma. In this study, we propose that attenuated total reflection Fourier transform infrared in conjunction with principal component analysis - linear discriminant analysis and support vector machine multivariate algorithms holds a potential as a sensitive tool for the detection of hepatitis C virus-related hepatocellular carcinoma and the subsequent categorization of hepatocellular carcinoma into non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma.

METHODS

Freeze-dried sera samples collected from 31 hepatitis c virus related hepatocellular carcinoma patients and 30 healthy individuals, were used to acquire mid-infrared absorbance spectra (3500-900 cm-1) using attenuated total reflection Fourier transform infrared. Chemometric machine learning techniques were utilized to build principal component analysis - linear discriminant analysis and support vector machine discriminant models for the spectral data of hepatocellular carcinoma patients and healthy individuals. Sensitivity, specificity, and external validation on blind samples were calculated.

RESULTS

Major variations were observed in the two spectral regions i.e., 3500-2800 and 1800-900 cm-1. IR spectral signatures of hepatocellular carcinoma were reliably different from healthy individuals. Principal component analysis - linear discriminant analysis and support vector machine models computed 100% accuracy for diagnosing hepatocellular carcinoma. To classify the non-angio-invasive hepatocellular carcinoma/ angio-invasive hepatocellular carcinoma status, diagnostic accuracy of 86.21% was achieved for principal component analysis - linear discriminant analysis. While the support vector machine showed a training accuracy of 98.28% and a cross-validation accuracy of 82.75%. External validation for support vector machine based classification observed 100% sensitivity and specificity for accurately classifying the freeze-dried sera samples for all categories.

CONCLUSIONS

We present the specific spectral signatures for non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma, which were prominently differentiated from healthy individuals. This study provides an initial insight into the potential of attenuated total reflection Fourier transform infrared to diagnose hepatitis C virus related hepatocellular carcinoma but also to further categorize into non-angio-invasive and angio-invasive hepatocellular carcinoma.

Hepatocellular organellar abnormalities following elimination of hepatitis C virus

BACKGROUND AND AIMS

The future development of hepatocellular carcinoma (HCC) in patients after sustained virologic response (SVR) is an important issue. The purposes of this study were to investigate pathological alterations in organelle of the liver of SVR patients and to characterize organelle abnormalities that may be related to carcinogenesis after SVR.

METHODS

The ultrastructure of liver biopsy specimens from patients with chronic hepatitis C (CHC) and SVR were compared to cell and mouse models and assessed semi-quantitatively using transmission electron microscopy.

RESULTS

Hepatocytes in patients with CHC showed abnormalities in the nucleus, mitochondria, endoplasmic reticulum, lipid droplet, and pericellular fibrosis, comparable to those seen in hepatitis C virus (HCV)-infected mice and cells. DAA treatment significantly reduced organelle abnormalities such as the nucleus, mitochondria, and lipid droplet in the hepatocytes of patients and mice after SVR, and cured cells, but it did not change dilated/degranulated endoplasmic reticulum and pericellular fibrosis in patients and mice after SVR. Further, samples from patients with a post-SVR period of >1 year had significantly larger numbers of abnormalities in the mitochondria and endoplasmic reticulum than those of <1 year. A possible cause of organelle abnormalities in patients after SVR could be oxidative stress of the endoplasmic reticulum and mitochondria associated with abnormalities of the vascular system due to fibrosis. Interestingly, abnormal endoplasmic reticulum was associated with patients with HCC for >1 year after SVR.

CONCLUSIONS

These results indicate that patients with SVR exhibit a persistent disease state and require long-term follow-up to detect early signs of carcinogenesis.

Metabolic disorders induced by PNPLA3 and TM6SF2 gene variants affect chronic kidney disease in patients infected with non-genotype 3 hepatitis C virus

BACKGROUND

Patients with chronic hepatitis C virus (HCV) infections differ in their risk for metabolic disorders and chronic kidney disease (CKD). The aim of this study was to investigate the effect of metabolic disorders induced by genetic factors on CKD in HCV-infected patients.

METHODS

Patients with chronic non-genotype 3 HCV infection with or without CKD were examined. PNPLA3 and TM6SF2 variants were determined using high-throughput sequencing. The relationships of variants and different combinations with metabolic disorders were analyzed in CKD patients. Univariate and multivariate analyses were used to identify factors associated with CKD.

RESULTS

There were 1022 patients with chronic HCV infection, 226 with CKD and 796 without CKD. The CKD group had more severe metabolic disorders, and also had higher prevalences of liver steatosis, the PNPLA3 rs738409 non-CC genotype, and the TM6SF2 rs58542926 CC genotype (all P < 0.05). Relative to patients with the PNPLA3 rs738409 CC genotype, patients with the non-CC genotype had a significantly decreased eGFR and a greater prevalence of advanced CKD (CKD G4-5). Patients with the TM6SF2 rs58542926 CC genotype had a lower eGFR and a higher prevalence of CKD G4-5 than those with the non-CC genotype. Multivariable analysis indicated that multiple metabolic abnormalities, including liver steatosis and the PNPLA3 rs738409 C > G variant, increased the risk of CKD, but the TM6SF2 rs58542926 C > T variant decreased the risk of CKD.

CONCLUSION

Specific PNPLA3 rs738409 and TM6SF2 rs58542926 variants are independent risk factors for CKD in patients with chronic HCV infections and are associated with the severity of renal injury.

Endosomal egress and intercellular transmission of hepatic ApoE-containing lipoproteins and its exploitation by the hepatitis C virus

Liver-generated plasma Apolipoprotein E (ApoE)-containing lipoproteins (LPs) (ApoE-LPs) play central roles in lipid transport and metabolism. Perturbations of ApoE can result in several metabolic disorders and ApoE genotypes have been associated with multiple diseases. ApoE is synthesized at the endoplasmic reticulum and transported to the Golgi apparatus for LP assembly; however, the ApoE-LPs transport pathway from there to the plasma membrane is largely unknown. Here, we established an integrative imaging approach based on a fully functional fluorescently tagged ApoE. We found that newly synthesized ApoE-LPs accumulate in CD63-positive endosomes of hepatocytes. In addition, we observed the co-egress of ApoE-LPs and CD63-positive intraluminal vesicles (ILVs), which are precursors of extracellular vesicles (EVs), along the late endosomal trafficking route in a microtubule-dependent manner. A fraction of ApoE-LPs associated with CD63-positive EVs appears to be co-transmitted from cell to cell. Given the important role of ApoE in viral infections, we employed as well-studied model the hepatitis C virus (HCV) and found that the viral replicase component nonstructural protein 5A (NS5A) is enriched in ApoE-containing ILVs. Interaction between NS5A and ApoE is required for the efficient release of ILVs containing HCV RNA. These vesicles are transported along the endosomal ApoE egress pathway. Taken together, our data argue for endosomal egress and transmission of hepatic ApoE-LPs, a pathway that is hijacked by HCV. Given the more general role of EV-mediated cell-to-cell communication, these insights provide new starting points for research into the pathophysiology of ApoE-related metabolic and infection-related disorders.

The Early Secretory Pathway Is Crucial for Multiple Aspects of the Hepatitis C Virus Life Cycle

Although most of the early events of the hepatitis C virus (HCV) life cycle are well characterized, our understanding of HCV egress is still unclear. Some reports implicate the conventional endoplasmic reticulum (ER)-Golgi route, while some propose noncanonical secretory routes. Initially, the envelopment of HCV nucleocapsid occurs by budding into the ER lumen. Subsequently, the HCV particle exit from the ER is assumed to be mediated by coat protein complex II (COPII) vesicles. COPII vesicle biogenesis also involves the recruitment of cargo to the site of vesicle biogenesis via interaction with COPII inner coat proteins. We investigated the modulation and the specific role of the individual components of the early secretory pathway in HCV egress. We observed that HCV inhibits cellular protein secretion and triggers the reorganization of the ER exit sites and ER-Golgi intermediate compartments (ERGIC). Gene-specific knockdown of the components of this pathway such as SEC16A, TFG, ERGIC-53, and COPII coat proteins demonstrated the functional significance of these components and the distinct role played by these proteins in various aspects of the HCV life cycle. SEC16A is essential for multiple steps in the HCV life cycle, whereas TFG is specifically involved in HCV egress and ERGIC-53 is crucial for HCV entry. Overall, our study establishes that the components of the early secretory pathway are essential for HCV propagation and emphasize the importance of the ER-Golgi secretory route in this process. Surprisingly, these components are also required for the early stages of the HCV life cycle due to their role in overall intracellular trafficking and homeostasis of the cellular endomembrane system. IMPORTANCE The virus life cycle involves entry into the host, replication of the genome, assembly of infectious progeny, and their subsequent release. Different aspects of the HCV life cycle, including entry, genome replication, and assembly, are well characterized; however, our understanding of the HCV release is still not clear and subject to debate due to varied findings. Here, we attempted to address this controversy and enhance our understanding of HCV egress by evaluating the role of the different components of the early secretory pathway in the HCV life cycle. To our surprise, we found that the components of the early secretory pathway are not only essential for HCV release but also contribute to many other earlier events of the HCV life cycle. This study emphasizes the importance of the early secretory pathway for the establishment of productive HCV infection in hepatocytes.

Oncogenic viruses and host lipid metabolism: a new perspective

As noncellular organisms, viruses do not have their own metabolism and rely on the metabolism of host cells to provide energy and metabolic substances for their life cycles. Increasing evidence suggests that host cells infected with oncogenic viruses have dramatically altered metabolic requirements and that oncogenic viruses produce substances used for viral replication and virion production by altering host cell metabolism. We focused on the processes by which oncogenic viruses manipulate host lipid metabolism and the lipid metabolism disorders that occur in oncogenic virus-associated diseases. A deeper understanding of viral infections that cause changes in host lipid metabolism could help with the development of new antiviral agents as well as potential new therapeutic targets.

The Association between Statins and Liver Cancer Risk in Patients with Heart Failure: A Nationwide Population-Based Cohort Study

Heart failure (HF) and cancer have similar risk factors. HMG-CoA reductase inhibitors, also known as statins, are chemoprotective agents against carcinogenesis. We aimed to evaluate the chemoprotective effects of statins against liver cancer in patients with HF. This cohort study enrolled patients with HF aged ≥20 years between 1 January 2001 and 31 December 2012 from the National Health Insurance Research Database in Taiwan. Each patient was followed to assess liver cancer risk. A total of 25,853 patients with HF were followed for a 12-year period; 7364 patients used statins and 18,489 did not. The liver cancer risk decreased in statin users versus non-users (adjusted hazard ratio (aHR) = 0.26, 95% confidence interval (CI): 0.20-0.33) in the entire cohort in the multivariate regression analysis. In addition, both lipophilic and hydrophilic statins reduced the liver cancer risk in patients with HF (aHR 0.34, 95% CI: 0.26-0.44 and aHR 0.42, 95% CI: 0.28-0.54, respectively). In the sensitivity analysis, statin users in all dose-stratified subgroups had a reduced liver cancer risk regardless of age, sex, comorbidity, or other concomitant drug use. In conclusion, statins may decrease liver cancer risk in patients with HF.

Label-free proteomics analysis on the envelope of budded viruses of Bombyx mori nucleopolyhedrovirus harboring differential localized GP64

Bombyx mori nucleopolyhedrovirus (BmNPV) GP64 is the key membrane fusion protein that mediates budded virus (BV) infection. We recently reported that BmNPV GP64's n-region of signal peptide (SP) blocked the SP-cleavage and mediated GP64 localization on the plasma membrane (PM); n-region (SP^∆nGP64) absence caused GP64 intracellular localization, however, SP^∆nGP64 was still incorporated into virion to generate BVs with lower infectivity. To better understand the biogenesis of the envelope of BmNPV BV, we conducted a label-free ESI mass spectrometry analysis of the envelope of purified BVs harboring PM localized GP64 or intracellular localized SP^∆nGP64. The results indicated that 31 viral proteins were identified on the envelope, among which 15 were reported in other viruses. The other 16 proteins were first reported in BmNPV BV, including the BmNPV-specific protein BRO-A and proteins associated with vesicle transportation. Six proteins with significant intensity differences were detected in virions with differential localized GP64, and five specific proteins were identified in virions with GP64. Meanwhile, we identified 81 host proteins on the envelope, and seven lipoproteins were first identified in baculovirus virion; other 74 proteins are involved in the cytoskeleton, DNA-binding, vesicle transport, etc. In the meantime, eight and five specific host proteins were, respectively, identified in GP64 and SP^∆nGP64's virions. The two virions shared 68 common host proteins, and 8 proteins were identified on their envelopes with a significant difference. This study provides new insight into the protein composition of BmNPV BV and a clue for further investigation of the budding mechanism of BmNPV.

Hepatitis C virus nonstructural protein 4B induces lipogenesis via the Hippo pathway

Hepatitis C virus (HCV) infection causes abnormal lipid metabolism in hepatocytes, which leads to hepatic steatosis and even hepatocellular carcinoma. HCV nonstructural protein 4B (NS4B) has been reported to induce lipogenesis, but the underlying mechanism is unclear. In this study, western blots were performed to investigate the effect of NS4B protein levels on key effectors of the Hippo and AKT signaling pathways. Yes-associated protein (YAP) and moesin-ezrin-radixin-like protein (Merlin) are effectors of the Hippo pathway. NS4B downregulated Merlin and phosphorylated YAP (p-YAP) protein expression while increasing the expression of the key AKT pathway proteins p-AKT and NF-κB. By observing the levels of AKT pathway proteins when Merlin was overexpressed or silenced, it was determined that Merlin mediates the AKT pathway. We suggest that HCV NS4B may mediate the AKT signaling pathway by inhibiting the Hippo pathway. Lipid droplets were observed in Huh7.5 cells overexpressing NS4B, and they increased significantly in number when Merlin was silenced. Overexpression of NS4B and Merlin silencing enhanced the expression of sterol regulatory element binding proteins (SREBPs), which have been demonstrated to be key regulatory factors controlling fatty acid synthesis. NS4B and Merlin silencing also enhanced the in vitro proliferative capacity of hepatocellular carcinoma cells. In conclusion, NS4B induces lipogenesis via the effect of the Hippo-YAP pathway on the AKT signaling pathway and thereby plays a significant role in the pathogenesis of HCV-associated diseases.

Metabolic reprogramming and lipid droplets are involved in Zika virus replication in neural cells

Zika virus (ZIKV) infection is a global public health concern linked to adult neurological disorders and congenital diseases in newborns. Host lipid metabolism, including lipid droplet (LD) biogenesis, has been associated with viral replication and pathogenesis of different viruses. However, the mechanisms of LD formation and their roles in ZIKV infection in neural cells are still unclear. Here, we demonstrate that ZIKV regulates the expression of pathways associated with lipid metabolism, including the upregulation and activation of lipogenesis-associated transcription factors and decreased expression of lipolysis-associated proteins, leading to significant LD accumulation in human neuroblastoma SH-SY5Y cells and in neural stem cells (NSCs). Pharmacological inhibition of DGAT-1 decreased LD accumulation and ZIKV replication in vitro in human cells and in an in vivo mouse model of infection. In accordance with the role of LDs in the regulation of inflammation and innate immunity, we show that blocking LD formation has major roles in inflammatory cytokine production in the brain. Moreover, we observed that inhibition of DGAT-1 inhibited the weight loss and mortality induced by ZIKV infection in vivo. Our results reveal that LD biogenesis triggered by ZIKV infection is a crucial step for ZIKV replication and pathogenesis in neural cells. Therefore, targeting lipid metabolism and LD biogenesis may represent potential strategies for anti-ZIKV treatment development.

Evaluation of differentially expressed genes during replication using gene expression landscape of monkeypox-infected MK2 cells: A bioinformatics and systems biology approach to understanding the genomic pattern of viral replication

PURPOSE

The current outbreak of monkeypox (MPX) has created colossal concerns. However, immense research gaps have been noted in our understanding of the replication process, machinery, and genomic landscape during host cell infection. To fill this gap, differentially expressed genes (DEGs) were comprehensively analyzed during viral replication in host (MK2) cells.

METHODS

We used a microarray GEO dataset which was divided into three groups: control, MPXV-infected MK2 cells at 3 h, and MPXV-infected MK2 cells at 7 h. Using the dataset, DEG analysis, PPI network analysis, co-expression, and pathway analysis were conducted using bioinformatics, systems biology, and statistical approaches.

RESULTS

We identified 250 DEGs and 24 top-ranked genes. During the DEG analysis, we identified eight up-regulated genes (LOC695323, TMEM107, LOC695427, HIST1H2AD, LOC705469, PMAIP1, HIST1H2BJ, and HIST1H3D) and 16 down-regulated genes (HOXA9, BAMBI, LMO4, PAX6, AJUBA, CREBRF, CD24, JADE1, SLC7A11, EID2, SOX4, B4GALT5, PPARGC1A, BUB3, SOS2, and CDK19). We also developed PPI networks and performed co-expression analyses using the top-ranked genes. Furthermore, five genes were listed for co-expression pattern analysis.

CONCLUSIONS

This study will help in better understanding the replication process, machinery, and genomic landscape of the virus. This will further aid the discovery and development of therapeutics against viruses.

Transcriptome profiling highlights regulated biological processes and type III interferon antiviral responses upon Crimean-Congo hemorrhagic fever virus infection

Crimean-Congo hemorrhagic fever virus (CCHFV) is a biosafety level-4 (BSL-4) pathogen that causes Crimean-Congo hemorrhagic fever (CCHF) characterized by hemorrhagic manifestation, multiple organ failure and high mortality rate, posing great threat to public health. Despite the recently increasing research efforts on CCHFV, host cell responses associated with CCHFV infection remain to be further characterized. Here, to better understand the cellular response to CCHFV infection, we performed a transcriptomic analysis in human kidney HEK293 ​cells by high-throughput RNA sequencing (RNA-seq) technology. In total, 496 differentially expressed genes (DEGs), including 361 up-regulated and 135 down-regulated genes, were identified in CCHFV-infected cells. These regulated genes were mainly involved in host processes including defense response to virus, response to stress, regulation of viral process, immune response, metabolism, stimulus, apoptosis and protein catabolic process. Therein, a significant up-regulation of type III interferon (IFN) signaling pathway as well as endoplasmic reticulum (ER) stress response was especially remarkable. Subsequently, representative DEGs from these processes were well validated by RT-qPCR, confirming the RNA-seq results and the typical regulation of IFN responses and ER stress by CCHFV. Furthermore, we demonstrate that not only type I but also type III IFNs (even at low dosages) have substantial anti-CCHFV activities. Collectively, the data may provide new and comprehensive insights into the virus-host interactions and particularly highlights the potential role of type III IFNs in restricting CCHFV, which may help inform further mechanistic delineation of the viral infection and development of anti-CCHFV strategies.

Deciphering the roles of myeloid derived suppressor cells in viral oncogenesis

Myeloid derived suppressor cells (MDSCs) are a heterogenous population of myeloid cells derived from monocyte and granulocyte precursors. They are pathologically expanded in conditions of ongoing inflammation where they function to suppress both innate and adaptive immunity. They are subdivided into three distinct subsets: monocytic (M-) MDSC, polymorphonuclear (or neutrophilic) (PMN-) MDSC and early-stage (e-) MDSC that may exhibit differential function in different pathological scenarios. However, in cancer they are associated with inhibition of the anti-tumour immune response and are universally associated with a poor prognosis. Seven human viruses classified as Group I carcinogenic agents are jointly responsible for nearly one fifth of all human cancers. These viruses represent a large diversity of species, including DNA, RNA and retroviridae. They include the human gammaherpesviruses (Epstein Barr virus (EBV) and Kaposi's Sarcoma-Associated Herpesvirus (KSHV), members of the high-risk human papillomaviruses (HPVs), hepatitis B and C (HBV, HCV), Human T cell leukaemia virus (HTLV-1) and Merkel cell polyomavirus (MCPyV). Each of these viruses encode an array of different oncogenes that perturb numerous cellular pathways that ultimately, over time, lead to cancer. A prerequisite for oncogenesis is therefore establishment of chronic infection whereby the virus persists in the host cells without being eradicated by the antiviral immune response. Although some of the viruses can directly modulate the immune response to enable persistence, a growing body of evidence suggests the immune microenvironment is modulated by expansions of MDSCs, driven by viral persistence and oncogenesis. It is likely these MDSCs play a role in loss of immune recognition and function and it is therefore essential to understand their phenotype and function, particularly given the increasing importance of immunotherapy in the modern arsenal of anti-cancer therapies. This review will discuss the role of MDSCs in viral oncogenesis. In particular we will focus upon the mechanisms thought to drive the MDSC expansions, the subsets expanded and their impact upon the immune microenvironment. Importantly we will explore how MDSCs may modulate current immunotherapies and their impact upon the success of future immune-based therapies.

Cardiometabolic effects of direct-acting antivirals in patients with hepatitis C

Hepatitis C virus (HCV) has long been associated with several extrahepatic manifestations, including increased cardiovascular risk. The emergence of direct-acting antivirals (DAAs) has allowed us to evaluate the potential reversal of these manifestations after successful treatment. Therefore, many studies have provided significant takeaways regarding the positive effect of DAAs therapy on insulin resistance, type 2 diabetes mellitus, cardiovascular disease and atherosclerosis. In contrast, studies have shown detrimental effects on lipid metabolism and indeterminate results regarding renal function and uric acid metabolism. Nevertheless, as more and more patients achieve sustained virological response, the effects of HCV eradication on cardiometabolic processes will be extensively studied, allowing more reliable conclusions on the extent of extrahepatic outcomes.

The Role of Cytosolic Lipid Droplets in Hepatitis C Virus Replication, Assembly, and Release

The hepatitis C virus (HCV) causes chronic hepatitis by establishing a persistent infection. Patients with chronic hepatitis frequently develop hepatic cirrhosis, which can lead to liver cancer-the progressive liver damage results from the host's immune response to the unresolved infection. The HCV replication process, including the entry, replication, assembly, and release stages, while the virus circulates in the bloodstream, it is intricately linked to the host's lipid metabolism, including the dynamic of the cytosolic lipid droplets (cLDs). This review article depicts how this interaction regulates viral cell tropism and aids immune evasion by coining viral particle characteristics. cLDs are intracellular organelles that store most of the cytoplasmic components of neutral lipids and are assumed to play an increasingly important role in the pathophysiology of lipid metabolism and host-virus interactions. cLDs are involved in the replication of several clinically significant viruses, where viruses alter the lipidomic profiles of host cells to improve viral life cycles. cLDs are involved in almost every phase of the HCV life cycle. Indeed, pharmacological modulators of cholesterol synthesis and intracellular trafficking, lipoprotein maturation, and lipid signaling molecules inhibit the assembly of HCV virions. Likewise, small-molecule inhibitors of cLD-regulating proteins inhibit HCV replication. Thus, addressing the molecular architecture of HCV replication will aid in elucidating its pathogenesis and devising preventive interventions that impede persistent infection and prevent disease progression. This is possible via repurposing the available therapeutic agents that alter cLDs metabolism. This review highlights the role of cLD in HCV replication.

Myocardial perfusion reserve in patients with chronic hepatitis C before and after direct-acting antiviral treatment-a pilot study

INTRODUCTION

Patients with chronic hepatitis C (CHC) have an increased risk of atherosclerotic cardiovascular disease which may be due to inflammation and endothelial dysfunction caused by the chronic infection. In this prospective pilot study, we assessed, for the first time among patients with CHC the myocardial perfusion reserve (MPR) by Rubidium-82 (⁸² Rb) positron emission tomography (PET)/computed tomography (CT) before and after direct-acting antiviral (DAA) treatment and compared them with biomarkers of systemic inflammation and endothelial dysfunction.

METHODS

We included 10 patients with CHC who received 8 or 12 weeks of DAA treatment. To obtain the MPR, a cardiac ⁸² Rb PET/CT scan at rest and adenosine-induced stress was performed at baseline and between 12 and 24 weeks post DAA treatment. Additionally, markers of endothelial dysfunction and inflammation were measured at baseline and 12 weeks after DAA treatment.

RESULTS

All 10 patients achieved cure and the median age was 50 (range: 40-62 years). The median MPR before treatment was 3.1 (range: 2.3-4.8) compared to 2.9 (range: 2.2-4.1) after DAA treatment p = 0.63. Also, cure after DAA treatment was not associated with an overall significant decrease in markers of endothelial dysfunction and inflammation.

DISCUSSION

Cure after DAA treatment in patients with CHC did not improve coronary microvascular function nor did it lead to a decrease in soluble markers of cardiovascular risk in the given time frame where the patients were followed. It should be noted, that MPR before DAA treatment was in the normal range. Considering the small sample size and short follow-up time, further studies are warranted to determine if viral clearance has an effect on coronary microvascular function and endothelial dysfunction.

Co-opted membranes, lipids, and host proteins: what have we learned from tombusviruses?

Positive-strand RNA viruses replicate in intracellular membranous structures formed after virus-driven intensive manipulation of subcellular organelles and membranes. These unique structures are called viral-replication organelles (VROs). To build VROs, the replication proteins coded by (+)RNA viruses co-opt host proteins, including membrane-shaping, lipid synthesis, and lipid-modification enzymes to create an optimal microenvironment that (i) concentrates the viral replicase and associated host proteins and the viral RNAs; (ii) regulates enzymatic activities and spatiotemporally the replication process; and (iii) protects the viral RNAs from recognition and degradation by the host innate immune defense. Tomato bushy stunt virus (TBSV), a plant (+)RNA virus, serves as an advanced model to study the interplay among viral components, co-opted host proteins, lipids, and membranes. This review presents our current understanding of the complex interaction between TBSV and host with panviral implications.

Cathepsin B and Plasma Kallikrein Are Reliable Biomarkers to Discriminate Clinically Significant Hepatic Fibrosis in Patients with Chronic Hepatitis-C Infection

We aimed to determine the biomarker performance of the proteolytic enzymes cathepsin B (Cat B) and plasma kallikrein (PKa) and transforming growth factor (TGF)-β to detect hepatic fibrosis (HF) in chronic hepatitis C (CHC) patients. We studied 53 CHC patients and 71 healthy controls (HCs). Hepatic-disease stage was determined by liver biopsies, aminotransferase:platelet ratio index (APRI) and Fibrosis (FIB)4. Hepatic inflammation and HF in CHC patients were stratified using the METAVIR scoring system. Cat-B and PKa activities were monitored fluorometrically. Serum levels of TGF-β (total and its active form) were determined using ELISA-like fluorometric methods. Increased serum levels of Cat B and PKa were found (p < 0.0001) in CHC patients with clinically significant HF and hepatic inflammation compared with HCs. Levels of total TGF-β (p < 0.0001) and active TGF-β (p < 0.001) were increased in CHC patients compared with HCs. Cat-B levels correlated strongly with PKa levels (r = 0.903, p < 0.0001) in CHC patients but did not correlate in HCs. Levels of Cat B, PKa and active TGF-β increased with the METAVIR stage of HF. Based on analyses of receiver operating characteristic (ROC) curves, Cat B and PKa showed high diagnostic accuracy (area under ROC = 0.99 ± 0.02 and 0.991 ± 0.007, respectively) for distinguishing HF in CHC patients from HCs. Taken together, Cat B and PKa could be used as circulating biomarkers to detect HF in HCV-infected patients.

A Multiscale Study of Phosphorylcholine Driven Cellular Phenotypic Targeting

Phenotypic targeting requires the ability of the drug delivery system to discriminate over cell populations expressing a particular receptor combination. Such selectivity control can be achieved using multiplexed-multivalent carriers often decorated with multiple ligands. Here, we demonstrate that the promiscuity of a single ligand can be leveraged to create multiplexed-multivalent carriers achieving phenotypic targeting. We show how the cellular uptake of poly(2-(methacryloyloxy)ethyl phosphorylcholine)-poly(2-(diisopropylamino)ethyl methacry-late) (PMPC-PDPA) polymersomes varies depending on the receptor expression among different cells. We investigate the PMPC-PDPA polymersome insertion at the single chain/receptor level using all-atom molecular modeling. We propose a theoretical statistical mechanics-based model for polymersome-cell association that explicitly considers the interaction of the polymersome with the cell glycocalyx shedding light on its effect on the polymersome binding. We validate our model experimentally and show that the binding energy is a nonlinear function, allowing us to tune the interaction by varying the radius and degree of polymerization. Finally, we show that PMPC-PDPA polymersomes can be used to target monocytes in vivo due to their promiscuous interaction with SRB1, CD36, and CD81.

Non-Targeted Metabolomic Analysis of Chicken Kidneys in Response to Coronavirus IBV Infection Under Stress Induced by Dexamethasone

Stress in poultry can lead to changes in body metabolism and immunity, which can increase susceptibility to infectious diseases. However, knowledge regarding chicken responses to viral infection under stress is limited. Dexamethasone (Dex) is a synthetic glucocorticoid similar to that secreted by animals under stress conditions, and has been widely used to induce stress in chickens. Herein, we established a stress model in 7-day-old chickens injected with Dex to elucidate the effects of stress on IBV replication in the kidneys. The metabolic changes, immune status and growth of the chickens under stress conditions were comprehensively evaluated. Furthermore, the metabolic profile, weight gain, viral load, serum cholesterol levels, cytokines and peripheral blood lymphocyte ratio were compared in chickens treated with Dex and infected with IBV. An LC-MS/MS-based metabolomics method was used to examine differentially enriched metabolites in the kidneys. A total of 113 metabolites whose abundance was altered after Dex treatment were identified, most of which were lipids and lipid-like molecules. The principal metabolic alterations in chicken kidneys caused by IBV infection included fatty acid, valine, leucine and isoleucine metabolism. Dex treatment before and after IBV infection mainly affected the host’s tryptophan, phenylalanine, amino sugar and nucleotide sugar metabolism. In addition, Dex led to up-regulation of serum cholesterol levels and renal viral load in chickens, and to the inhibition of weight gain, peripheral blood lymphocytes and IL-6 production. We also confirmed that the exogenous cholesterol in DF-1 cells promoted the replication of IBV. However, whether the increase in viral load in kidney tissue is associated with the up-regulation of cholesterol levels induced by Dex must be demonstrated in future experiments. In conclusion, chick growth and immune function were significantly inhibited by Dex. Host cholesterol metabolism and the response to IBV infection are regulated by Dex. This study provides valuable insights into the molecular regulatory mechanisms in poultry stress, and should support further research on the intrinsic link between cholesterol metabolism and IBV replication under stress conditions.

Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control

Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.

Impact of the PNPLA3 genotype on the risk of hepatocellular carcinoma after hepatitis C virus eradication

Almost all chronic hepatitis C (CHC) patients can achieve sustained virological response (SVR) with direct-acting antivirals. However, the development of hepatocellular carcinoma (HCC), even after the achievement of SVR, continues to be a serious problem. The aim of this study was to assess the association between host genetic factors and de novo HCC after SVR. This single-center, retrospective study consisted of 442 consecutive CHC patients without a history of HCC who achieved SVR through interferon (IFN)-based and IFN-free therapy. Predictive factors associated with the development of HCC were determined by the Cox proportional hazards model. The single nucleotide polymorphism (SNP) genotyping data of 223 patients were available for analysis. Of the seven SNPs analyzed in this study, only the patatin-like phospholipase domain containing 3 (PNPLA3) rs738409 GG genotype was significantly, positively associated with the development of de novo HCC after adjusting for age, sex, and fibrosis status (adjusted hazard ratio [aHR] 5.66, P=0.003). In multivariable analysis, age (aHR 1.05, P=0.007), advanced fibrosis (aHR 2.69, P=0.019), α-fetoprotein at post-12 weeks of treatment ≥7.0 ng/mL (aHR 3.85, P=0.001), and PNPLA3 GG genotype (aHR 3.02, P=0.004) were extracted as independent predictors of the development of de novo HCC. In conclusion, the PNPLA3 genotype was independently associated with the de novo HCC of CHC patients who achieved SVR. Such detailed knowledge of host genetic factors will be useful for HCC surveillance after HCV elimination. This article is protected by copyright. All rights reserved.

Impact of direct-acting antiviral therapy on metabolic profiles and adiponectin serum level in different categories of patients with chronic hepatitis C infection

Background

Infection with the hepatitis C virus (HCV) is a worldwide health problem. HCV infection is linked to a variety of metabolic abnormalities as it interferes with lipid metabolism, causing steatosis and a wide range of adipocytokine alterations, as well as impairing glucose metabolism, resulting in a rising prevalence of insulin resistance (IR) and type 2 diabetes. Over the last few years, numerous oral anti-HCV medicines (direct-acting antivirals; DAAs) have been introduced. With DAA therapy, HCV can now be eradicated from the infected host within 12 weeks. There is a need for more research because there is minimal information on the effects of DAA therapy on metabolic profiles, lipid profiles, and adiponectin levels. Thus, the purpose of this study was to see how direct-acting antivirals (DAAs) affected metabolic profiles and serum adiponectin levels in 2 different categories of Egyptian patients with chronic hepatitis C infection. This study included 100 patients with chronic HCV who were separated into two groups. Group I consisted of 50 patients who were treated for 12 weeks with sofosbuvir, daclatasvir, and ribavirin). Group II consisted of 50 patients who were treated for 12 weeks with ombitasvir, paritaprevir, and ritonavir/ribavirin. This regimen was chosen because these patients had an eGFR of 30 ml/min. Fasting lipid profiles (total cholesterol, triglyceride, HDL, and LDL), metabolic profiles (fasting blood sugar, fasting insulin, HOMA-IR, and HbA1C), and serum adiponectin levels were measured before and after the end of treatment.

Results

Statistical analysis of the data showed a significant difference in the lipid profile in group I before and after treatment, as we found a significant reduction in serum triglycerides after treatment (113.2 ± 22.9 mg/dL vs 105.6 ± 23.2 mg/dL, P < 0.001) and a significant elevation of serum total cholesterol, LDL, and HDL after treatment (TC: 153.2 ± 20.1 mg/dL vs 174.1 ± 19 mg/dL, P < 0.001; LDL: 74.7 ± 9.9 mg/dL vs 93.3 ± 12 mg/dL, P < 0.001; HDL: 54.6 ± 10.1 mg/dL vs 57.2 ± 10.3 mg/dL, P 0.010). But in group II, there was no significant difference in the lipid profile before and after treatment. We also found a significant reduction in fasting insulin, HOMA-IR, and HBA1C after treatment in group I (fasting insulin: 11.4 ± 3.3 (µU/L)/ml vs 9.7 ± 2.2 (µU/L)/ml, P < 0.001; HOMA-IR: 2.7 ± 0.9 vs 2.2 ± 0.6, P < 0.001; HBA1C: 5.6 ± 0.4 vs 5.4 ± 0.3, P 0.003). But in group II, there was no significant difference in fasting insulin, HOMA-IR, and HBA1C before and after treatment. Also, we found that there were no significant changes in the serum adiponectin level in either group before or after treatment.

Conclusion

HCV clearance with DAAs had an impact on the lipid and metabolic profiles of the patients at the end of treatment. This could depend on the type of DAAs used in the treatment, the stage of the liver disease, and the associated conditions of patients. However, serum adiponectin levels are unaffected.

Real-Life Early Anthropometric, Lipid and Liver Changes after Direct-Acting Antiviral Therapy in PLWHIV with HCV Co-Infection

Treatment with interferon-free direct-acting antivirals (DAA) has become the gold standard in chronic hepatitis C virus (HCV) infection. Nevertheless, little research about the metabolic impact of achieving sustained virological response (SVR) is available in HCV/HIV co-infected patients. This research aimed to evaluate early anthropometric, lipid and liver parameters changes after achieving SVR 12 weeks after treatment (SVR12). A real-life retrospective descriptive before-after study assessed 128 DAA treatment episodes from 2015 to 2019 in HCV/HIV co-infected patients. Anthropometric parameters (weight, body mass index), lipid profile, genotype (GT) and viral load, liver data (basics laboratory necroinflammatory parameters and transient elastography (TE)) were collected before treatment with DAA (baseline), and when SVR12 was achieved. Significant increases (p < 0.01) were found in the early lipid profile, measured by LDLc (84.6 ± 35.0 vs. 108.6 ± 35.1 mg/dL) and total cholesterol (161.3 ± 41.0 vs. 183.3 ± 41.6 mg/dL). Significant changes (p < 0.05) were found in liver parameters, measured by ALT (58.2 ± 34.0 vs. 22.0 ± 16.0 U/L), bilirubin (0.8 ± 0.6 vs. 0.6 ± 0.5 mg/dL), albumin (4.2 ± 0.4 vs. 4.3 ± 0.3 g/dL) and liver stiffness (LS) (13.7 ± 13.3 vs. 11.8 ± 12.1 kPa). The main conclusions were that the use of DAA has an early negative impact on lipid metabolism. Achieving SVR12 against HCV leads to an early improvement in liver function and LS in HCV/HIV co-infected patients without interference with antiretroviral treatment (ART) and DAA. Short-term close lipid monitoring may be necessary when combining protease inhibitors. HCV-GT-3/HIV co-infected patients might require further close monitoring for residual fibrosis. These findings can be relevant for actual clinical practice.

Coronavirus Infection and Cholesterol Metabolism

Host cholesterol metabolism remodeling is significantly associated with the spread of human pathogenic coronaviruses, suggesting virus-host relationships could be affected by cholesterol-modifying drugs. Cholesterol has an important role in coronavirus entry, membrane fusion, and pathological syncytia formation, therefore cholesterol metabolic mechanisms may be promising drug targets for coronavirus infections. Moreover, cholesterol and its metabolizing enzymes or corresponding natural products exert antiviral effects which are closely associated with individual viral steps during coronavirus replication. Furthermore, the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 infections are associated with clinically significant low cholesterol levels, suggesting cholesterol could function as a potential marker for monitoring viral infection status. Therefore, weaponizing cholesterol dysregulation against viral infection could be an effective antiviral strategy. In this review, we comprehensively review the literature to clarify how coronaviruses exploit host cholesterol metabolism to accommodate viral replication requirements and interfere with host immune responses. We also focus on targeting cholesterol homeostasis to interfere with critical steps during coronavirus infection.

The Regulation of Integrated Stress Response Signaling Pathway on Viral Infection and Viral Antagonism

The integrated stress response (ISR) is an adaptational signaling pathway induced in response to different stimuli, such as accumulation of unfolded and misfolded proteins, hypoxia, amino acid deprivation, viral infection, and ultraviolet light. It has been known that viral infection can activate the ISR, but the role of the ISR during viral infection is still unclear. In some cases, the ISR is a protective mechanism of host cells against viral infection, while viruses may hijack the ISR for facilitating their replication. This review highlighted recent advances on the induction of the ISR upon viral infection and the downstream responses, such as autophagy, apoptosis, formation of stress granules, and innate immunity response. We then discussed the molecular mechanism of the ISR regulating viral replication and how viruses antagonize this cellular stress response resulting from the ISR.

Insights Into the Coinfections of Human Immunodeficiency Virus-Hepatitis B Virus, Human Immunodeficiency Virus-Hepatitis C Virus, and Hepatitis B Virus-Hepatitis C Virus: Prevalence, Risk Factors, Pathogenesis, Diagnosis, and Treatment

Human immunodeficiency virus, hepatitis B virus, and hepatitis C virus are three blood-borne viruses that can cause major global health issues by increasing severe morbidity. There is a high risk of coinfection with these viruses in individuals because of their same transmission routes through blood using shared needles, syringes, other injection equipment, sexual transmission, or even vertical transmission. Coinfection can cause various liver-related illnesses, non-hepatic organ dysfunction, followed by death compared to any of these single infections. The treatment of coinfected patients is complicated due to the side effects of antiviral medication, resulting in drug resistance, hepatotoxicity, and a lack of required responses. On the other hand, coinfected individuals must be treated with multiple drugs simultaneously, such as for HIV either along with HBV or HCV and HBV and HCV. Therefore, diagnosing, treating, and controlling dual infections with HIV, HBV, or HCV is complicated and needs further investigation. This review focuses on the current prevalence, risk factors, and pathogenesis of dual infections with HIV, HBV, and HCV. We also briefly overviewed the diagnosis and treatment of coinfections of these three blood-borne viruses.

Hepatitis C Virus-Related Central and Peripheral Nervous System Disorders

Hepatitis C Virus (HCV), despite being a hepatotropic virus, is the causative agent of many systemic disorders, such as vasculitis, autoimmune diseases, lymphoproliferative disorders, and a broad spectrum of neurological and psychiatric manifestations. Although symptoms have been misdiagnosed or underdiagnosed, only recently, evidence of direct (inflammatory) or indirect (immune-mediated) HCV-dependent cerebral effects has been established. HCV infection can promote acute inflammatory response, pro-coagulative status and ischemic disorders, and neurodegeneration. These effects rely on cerebral HCV replication, possibly mediated by blood-brain barrier alterations. Further study is needed to better understand the HCV-related mechanisms of brain damage.

Hepatitis C virus core protein uses triacylglycerols to fold onto the endoplasmic reticulum membrane

Lipid droplets (LDs) are involved in viral infections, but exactly how remains unclear. Here, we study the hepatitis C virus (HCV) whose core capsid protein binds to LDs but is also involved in the assembly of virions at the endoplasmic reticulum (ER) bilayer. We found that the amphipathic helix-containing domain of core, D2, senses triglycerides (TGs) rather than LDs per se. In the absence of LDs, D2 can bind to the ER membrane but only if TG molecules are present in the bilayer. Accordingly, the pharmacological inhibition of the diacylglycerol O-acyltransferase enzymes, mediating TG synthesis in the ER, inhibits D2 association with the bilayer. We found that TG molecules enable D2 to fold into alpha helices. Sequence analysis reveals that D2 resembles the apoE lipid-binding region. Our data support that TG in LDs promotes the folding of core, which subsequently relocalizes to contiguous ER regions. During this motion, core may carry TG molecules to these regions where HCV lipoviroparticles likely assemble. Consistent with this model, the inhibition of Arf1/COPI, which decreases LD surface accessibility to proteins and ER-LD material exchange, severely impedes the assembly of virions. Altogether, our data uncover a critical function of TG in the folding of core and HCV replication and reveals, more broadly, how TG accumulation in the ER may provoke the binding of soluble amphipathic helix-containing proteins to the ER bilayer.

Adherence to a Fish-Rich Dietary Pattern Is Associated with Chronic Hepatitis C Patients Showing Low Viral Load: Implications for Nutritional Management

Hepatitis C virus (HCV) infection is influenced by genetic (e.g., APOE polymorphisms) and environmental factors between the virus and the host. HCV modulates the host’s lipid metabolism but dietary components influence lipids and in vitro HCV RNA replication. Few data exist on the role of dietary features or patterns (DPs) in HCV infection. Herein, we aimed to evaluate the nutritional profiles of chronic HCV (CHC) and spontaneous clearance (SC) Mexican patients in the context of APOE alleles and their correlation with HCV-related variables. The fibrosis-related APOEε3 allele prevailed in CHC and SC patients, who had four DPs (“meat and soft drinks”, DP1; “processed animal and fried foods”, DP2; “Mexican-healthy”, DP3; and “fish-rich”, DP4). In CHC subjects, polyunsaturated fatty acid intake (PUFA ≥ 4.9%) was negatively associated, and fiber intake (≥21.5 g/day) was positively associated with a high viral load (p < 0.036). High adherence to fish-rich DP4 was associated with a higher frequency of CHC individuals consuming PUFA ≥ 4.9% (p = 0.004) and low viral load (p = 0.036), but a lower frequency of CHC individuals consuming fiber ≥21.5 g/day (p = 0.038). In SC and CHC individuals, modifying unhealthy DPs and targeting HCV-interacting nutrients, respectively, could be part of a nutritional management strategy to prevent further liver damage.

Role of Lipid Transfer Proteins (LTPs) in the Viral Life Cycle

Viruses are obligate parasites that depend on the host cell machinery for their replication and dissemination. Cellular lipids play a central role in multiple stages of the viral life cycle such as entry, replication, morphogenesis, and egress. Most viruses reorganize the host cell membranes for the establishment of viral replication complex. These specialized structures allow the segregation of replicating viral RNA from ribosomes and protect it from host nucleases. They also facilitate localized enrichment of cellular components required for viral replication and assembly. The specific composition of the lipid membrane governs its ability to form negative or positive curvature and possess a rigid or flexible form, which is crucial for membrane rearrangement and establishment of viral replication complexes. In this review, we highlight how different viruses manipulate host lipid transfer proteins and harness their functions to enrich different membrane compartments with specific lipids in order to facilitate multiple aspects of the viral life cycle.

Molecular Events Occurring in Lipophagy and Its Regulation in Flaviviridae Infection

Diseases caused by Flaviviridae have a wide global and economic impact due to high morbidity and mortality. Flaviviridae infection usually leads to severe, acute or chronic diseases, such as liver injury and liver cancer resulting from hepatitis C virus (HCV) infection, dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS) caused by dengue virus (DENV). Given the highly complex pathogenesis of Flaviviridae infections, they are still not fully understood at present. Accumulating evidence suggests that host autophagy is disrupted to regulate the life cycle of Flaviviridae. Organelle-specific autophagy is able to selectively target different organelles for quality control, which is essential for regulating cellular homeostasis. As an important sub process of autophagy, lipophagy regulates lipid metabolism by targeting lipid droplets (LDs) and is also closely related to the infection of a variety of pathogenic microorganisms. In this review, we briefly understand the LDs interaction relationship with Flaviviridae infection, outline the molecular events of how lipophagy occurs and the related research progress on the regulatory mechanisms of lipophagy in Flaviviridae infection. Exploring the crosstalk between viral infection and lipophagy induced molecular events may provide new avenues for antiviral therapy.

Dynamic interplay between the co-opted Fis1 mitochondrial fission protein and membrane contact site proteins in supporting tombusvirus replication

Plus-stranded RNA viruses have limited coding capacity and have to co-opt numerous pro-viral host factors to support their replication. Many of the co-opted host factors support the biogenesis of the viral replication compartments and the formation of viral replicase complexes on subverted subcellular membrane surfaces. Tomato bushy stunt virus (TBSV) exploits peroxisomal membranes, whereas the closely-related carnation Italian ringspot virus (CIRV) hijacks the outer membranes of mitochondria. How these organellar membranes can be recruited into pro-viral roles is not completely understood. Here, we show that the highly conserved Fis1 mitochondrial fission protein is co-opted by both TBSV and CIRV via direct interactions with the p33/p36 replication proteins. Deletion of FIS1 in yeast or knockdown of the homologous Fis1 in plants inhibits tombusvirus replication. Instead of the canonical function in mitochondrial fission and peroxisome division, the tethering function of Fis1 is exploited by tombusviruses to facilitate the subversion of membrane contact site (MCS) proteins and peroxisomal/mitochondrial membranes for the biogenesis of the replication compartment. We propose that the dynamic interactions of Fis1 with MCS proteins, such as the ER resident VAP tethering proteins, Sac1 PI4P phosphatase and the cytosolic OSBP-like oxysterol-binding proteins, promote the formation and facilitate the stabilization of virus-induced vMCSs, which enrich sterols within the replication compartment. We show that this novel function of Fis1 is exploited by tombusviruses to build nuclease-insensitive viral replication compartment.

Medicinal plants: Treasure for antiviral drug discovery

The pandemic of viral diseases like novel coronavirus (2019-nCoV) prompted the scientific world to examine antiviral bioactive compounds rather than nucleic acid analogous, protease inhibitors, or other toxic synthetic molecules. The emerging viral infections significantly associated with 2019-nCoV have challenged humanity's survival. Further, there is a constant emergence of new resistant viral strains that demand novel antiviral agents with fewer side effects and cell toxicity. Despite significant progress made in immunization and regenerative medicine, numerous viruses still lack prophylactic vaccines and specific antiviral treatments that are so often influenced by the generation of viral escape mutants. Of importance, medicinal herbs offer a wide variety of therapeutic antiviral chemotypes that can inhibit viral replication by preventing viral adsorption, adhering to cell receptors, inhibiting virus penetration in the host cell, and competing for pathways of activation of intracellular signals. The present review will comprehensively summarize the promising antiviral activities of medicinal plants and their bioactive molecules. Furthermore, it will elucidate their mechanism of action and possible implications in the treatment/prevention of viral diseases even when their mechanism of action is not fully understood, which could serve as the base for the future development of novel or complementary antiviral treatments.

Hepatitis C virus core protein: Not just a nucleocapsid building block, but an immunity and inflammation modulator

Coevolution occurs between viruses and their hosts. The hosts need to evolve means to eliminate pathogenic virus infections, and the viruses, for their own survival and multiplication, have to develop mechanisms to escape clearance by hosts. Hepatitis C virus (HCV) of Flaviviridae is a pathogen which infects human liver and causes hepatitis, a condition of liver inflammation. Unlike most of the other flaviviruses, HCV has an excellent ability to evade host immunity to establish chronic infection. The persistent liver infection leads to chronic hepatitis, liver cirrhosis, hepatocellular carcinoma (HCC), as well as extrahepatic HCV-related diseases. HCV genomic RNA only expresses 10 proteins, many of which bear functions, in addition to those involved in HCV life cycle, for assisting the virus to develop its persistency. HCV core protein is a structural protein which encapsulates HCV genomic RNA and assembles into nucleocapsids. The core protein is also found to exert functions to affect host inflammation and immune responses by altering a variety of host pathways. This paper reviews the studies regarding the HCV core protein-induced alterations of host immunity and inflammatory responses, as well as the involvements of the HCV core protein in pro- and anti-inflammatory cytokine stimulations, host cellular transcription, lipid metabolism, cell apoptosis, cell proliferations, immune cell differentiations, oxidative stress, and hepatocyte steatosis, which leads to liver fibrosis, cirrhosis, and HCC. Implications of roles played by the HCV core protein in therapeutic resistance are also discussed.

Anthropometric parameters and liver histology influence lipid metabolic changes in HCV chronic hepatitis on direct-acting antiviral treatment

Background

Hepatitis C virus (HCV) infection affects lipid metabolism. We investigated the impact of direct-acting antiviral (DAA) treatment on lipid metabolism in chronic hepatitis C (CHC), with a focus on the effects of anthropometric parameters and liver histology. We also analyzed the dynamics of metabolic indexes used to estimate cardiovascular risk.

Methods

In 49 patients with CHC treated with DAAs, lipid metabolic changes, anthropometric parameters, liver histology and cardiovascular risk indexes, including triglyceride to HDL ratio (Tr/HDL), fatty liver index (FLI) and visceral adiposity index (VAI) were evaluated at baseline (BL), end of treatment (EOT) and 12 [sustained virological response (SVR) 12] and 24 (SVR24) weeks after EOT.

Results

SVR occurred in 96% of cases. Total and LDL cholesterol and ApoB levels increased significantly between BL and EOT (P<0.001, <0.001 and 0.05, respectively) and remained stable thereafter. Total and LDL cholesterol significantly increased only in patients with higher BL waist circumference (P<0.01 and 0.009), fibrosis (P=0.002 and 0.005) and steatosis (P=0.043 and 0.033, respectively). HDL cholesterol significantly rose at SVR24. However, cardiovascular risk indexes (Tr/HDL ratio, FLI and VAI) did not significantly change during DAA treatment and follow up.

Conclusions

Patients with HCV eradication after DAA treatment develop a pro-atherogenic lipid pattern, which varies according to anthropometric parameters and liver histology. However, no increase of cardiovascular risk indexes occurs in the short-term. Total and LDL cholesterol should be monitored long-term in CHC patients cured from infection.

Lipid droplets fuel SARS-CoV-2 replication and production of inflammatory mediators

Viruses are obligate intracellular parasites that make use of the host metabolic machineries to meet their biosynthetic needs. Thus, identifying the host pathways essential for the virus replication may lead to potential targets for therapeutic intervention. The mechanisms and pathways explored by SARS-CoV-2 to support its replication within host cells are not fully known. Lipid droplets (LD) are organelles with major functions in lipid metabolism, energy homeostasis and intracellular transport, and have multiple roles in infections and inflammation. Here we described that monocytes from COVID-19 patients have an increased LD accumulation compared to SARS-CoV-2 negative donors. In vitro, SARS-CoV-2 infection were seen to modulate pathways of lipid synthesis and uptake as monitored by testing for CD36, SREBP-1, PPARγ, and DGAT-1 expression in monocytes and triggered LD formation in different human cell lines. LDs were found in close apposition with SARS-CoV-2 proteins and double-stranded (ds)-RNA in infected Vero cells. Electron microscopy (EM) analysis of SARS-CoV-2 infected Vero cells show viral particles colocalizing with LDs, suggestive that LDs might serve as an assembly platform. Pharmacological modulation of LD formation by inhibition of DGAT-1 with A922500 significantly inhibited SARS-CoV-2 replication as well as reduced production of mediators pro-inflammatory response. Taken together, we demonstrate the essential role of lipid metabolic reprograming and LD formation in SARS-CoV-2 replication and pathogenesis, opening new opportunities for therapeutic strategies to COVID-19.

In spite of the enormous scientific efforts to understand mechanisms of SARS-CoV2-induced disease and to develop strategies to control COVID-19 pandemic, many aspects of SARS-CoV2 biology and pathogenesis remain elusive. Several RNA viruses are able to modulate the host lipid metabolism and to recruit LDs to enhance their replication/particle assembling capacity through mechanisms that vary according to the virus and the host cell infected. The mechanisms and pathways explored by SARS-CoV-2 to support its replication within host cells are still largely unknown. Here we demonstrated that lipid droplets (LDs) participate in SARS-CoV2 infection favoring virus replication and heightening inflammatory mediator production. SARS-CoV2 infection increased the expression of key proteins in the regulation of lipid metabolism and the amounts of LDs per cell. In addition, we have found SARS-CoV2 and/or its components associated with LDs in infected cells, suggestive that LDs are recruited as part of replication compartment. Moreover, pharmacological inhibition of DGAT-1, a key enzyme for LD formation, reduces SARS-CoV2 replication, inflammatory mediator production and cell death. Our findings contribute to unveil the complex mechanism by which SARS-CoV-2 make use of cellular metabolism and organelles to coordinate different steps of the viral replication cycle and host immunity, opening new perspectives for SARS-CoV2 antiviral development.

Hepatitis C: clinical management and debated issues

Hepatitis C virus represents an important global health issue with 71 million of infected people in the word. Direct-acting antivirals are quite new molecules that hit specific Hepatitis C virus proteins useful for viral replication and assembly. Notably, Direct-acting antivirals bring to high sustained virological response rates showing also a great safety profile. This treatment revolution had an impact on transplantation world, in fact the number of liver transplants due to Hepatitis C virus-related cirrhosis and hepatocellular carcinoma is quickly decreasing. Even if this therapy has achieved excellent results in terms of morbility and mortality rates' reduction, there are some debated issues to consider. In the present review the main clinical challenges in every-day management of Hepatitis C virus patients treated with Direct-acting antivirals and the debated effects of viral clearance (metabolic, cardiovascular, immunologic and neoplastic) are discussed. The detection of barriers that can preclude the delivery of Hepatitis C virus care, is the most complex challenge for the scientific community. To obtain the Hepatitis C virus global eradication by 2030, as the World Health Organization has set, will be complex and laborious and will need a further multilevel effort.

Hepatitis C virus associated hepatocellular carcinoma

Liver cancer is a global problem and hepatocellular carcinoma (HCC) accounts for about 85% of this cancer. In the USA, etiologies and risk factors for HCC include chronic hepatitis C virus (HCV) infection, diabetes, non-alcoholic steatohepatitis (NASH), obesity, excessive alcohol drinking, exposure to tobacco smoke, and genetic factors. Chronic HCV infection appears to be associated with about 30% of HCC. Chronic HCV infection induces multistep changes in liver, involving metabolic disorders, steatosis, cirrhosis and HCC. Liver carcinogenesis requires initiation of neoplastic clones, and progression to clinically diagnose malignancy. Tumor progression associates with profound exhaustion of tumor-antigen-specific CD8⁺T cells, and accumulation of PD-1^hi CD8⁺T cells and Tregs. In this chapter, we provide a brief description of HCV and environmental/genetic factors, immune regulation, and highlight mechanisms of HCV associated HCC. We also underscore HCV treatment and recent paradigm of HCC progression, highlighted the current treatment and potential future therapeutic opportunities.