Upregulation of key factors of viral entry of corona- and influenza viruses upon TLR3-signaling in cells from the respiratory tract and clinical treatment options by 1,8-Cineol

At the end of the 2019 coronavirus pandemic (COVID-19), highly contagious variants of coronaviruses had emerged. Together with influenza viruses, different variants of the coronavirus currently cause most colds and require appropriate drug treatment. We have investigated the expression of important factors for the replication of these viruses, namely transmembrane protease serine subtype 2 (TMPRSS2), neuropilin1 (NRP1), and angiotensin converting enzyme 2 (ACE2) or tumor necrosis factor-α (TNF-α) after toll like receptor-3 (TLR-3) stimulation using RT-qPCR and flow cytometry (FC) analysis. As model served primary fibroblasts derived from the lung and nasal cavity, as well as epidermal stem cells and fully matured respiratory epithelium. The stimulated cell cultures were treated with pharmaceuticals (Dexamethasone and Enzalutamide) and the outcome was compared with the phytomedicine 1,8-Cineol. The stimulation of TLR3 is sufficient to induce the expression of exactly those targets that were highly expressed in the corresponding culture type, specifically ACE2 and TMPRSS2 in respiratory epithelial stem cells and NRP1 in fibroblast cells. It seems this self-perpetuating cycle of infection-driven upregulation of key viral replication factors by the innate immune system represents an evolutionary advantage for viruses using these transcripts as viral replication factors. Likewise, to the standard pharmaceuticals with proven clinical efficiency, 1,8-Cineol was able to disrupt this self-perpetuating cycle. Considering the minor side effects and negligible pharmacological interactions with other drugs, it is conceivable that an adjuvant or combinatorial therapy with 1,8-Cineol for respiratory diseases caused by corona- or influenza viruses would be beneficial.

Pediococcus pentosaceus MIANGUAN2 Alleviates Influenza Virus Infection by Modulating Gut Microbiota and Enhancing Short-Chain Fatty Acid Production

Influenza, a severe respiratory disease caused by the influenza virus, has long been a prominent threat to human health. An increasing number of studies have demonstrated that oral administration with probiotics may increase the immune response to lung infection via the gut-lung axis leading to the alleviation of the pulmonary disease. In this study, we evaluated the effects of oral administration of Pediococcus pentosaceus MIANGUAN2 (MIANGUAN2) on influenza infection in a mouse model. Our results showed that oral administration of MIANGUAN2 significantly improved weight loss, lung index, and lung pathology, and decreased lung viral load of influenza-infected mice. Additionally, MIANGUAN2-treated mice showed significantly lower levels of TNF-α, IL-1β, IFN-γ, and IL-12p70 and higher production of IL-4 in the lung. In accordance with this, the transcriptome analysis of the lung indicated that MIANGUAN2-treated mice had reduced expression of inflammation markers, such as TNF, apoptosis, and the NF-Kappa B pathway. Furthermore, the administration of MIANGUAN2 restored the SCFAs profiles through regulating the gut microbiota. SCFA-producing bacteria, such as p_Firmicutes, f_Lachnospiraceae, and f_Ruminococcaceae, were enriched in the MIANGUAN2-treated group compared with PBS-treated group. Consistently, the concentrations of SCFAs in the MIANGUAN2 group were significantly higher than those in the PBS-treated group. In addition, the concentrations of SCFAs were positively correlated with SCFA-producing bacteria, such as Ruminococcus, while being negatively correlated with the virial titers and proinflammatory cytokines. In conclusion, this animal study suggests that Pediococcus pentosaceus MIANGUAN2 may alleviate the influenza infection by altering the gut microbiota composition and increasing the levels of gut microbiota-derived SCFAs.

Comparative Investigation of Coincident Single Nucleotide Polymorphisms Underlying Avian Influenza Viruses in Chickens and Ducks

Avian influenza is a severe viral infection that has the potential to cause human pandemics. In particular, chickens are susceptible to many highly pathogenic strains of the virus, resulting in significant losses. In contrast, ducks have been reported to exhibit rapid and effective innate immune responses to most avian influenza virus (AIV) infections. To explore the distinct genetic programs that potentially distinguish the susceptibility/resistance of both species to AIV, the investigation of coincident SNPs (coSNPs) and their differing causal effects on gene functions in both species is important to gain novel insight into the varying immune-related responses of chickens and ducks. By conducting a pairwise genome alignment between these species, we identified coSNPs and their respective effect on AIV-related differentially expressed genes (DEGs) in this study. The examination of these genes (e.g., CD74, RUBCN, and SHTN1 for chickens and ABCA3, MAP2K6, and VIPR2 for ducks) reveals their high relevance to AIV. Further analysis of these genes provides promising effector molecules (such as IκBα, STAT1/STAT3, GSK-3β, or p53) and related key signaling pathways (such as NF-κB, JAK/STAT, or Wnt) to elucidate the complex mechanisms of immune responses to AIV infections in both chickens and ducks.

Vitisin B inhibits influenza A virus replication by multi-targeting neuraminidase and virus-induced oxidative stress

The development of drug-resistant influenza and new pathogenic virus strains underscores the need for antiviral therapeutics. Currently, neuraminidase (NA) inhibitors are commonly used antiviral drugs approved by the US Food and Drug Administration (FDA) for the prevention and treatment of influenza. Here, we show that vitisin B (VB) inhibits NA activity and suppresses H1N1 viral replication in MDCK and A549 cells. Reactive oxygen species (ROS), which frequently occur during viral infection, increase virus replication by activating the NF-κB signaling pathway, downmodulating glucose-6-phosphate dehydrogenase (G6PD) expression, and decreasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant response activity. VB decreased virus-induced ROS generation by increasing G6PD expression and Nrf2 activity, and inhibiting NF-κB translocation to the nucleus through IKK dephosphorylation. In addition, VB reduced body weight loss, increased survival, decreased viral replication and the inflammatory response in the lungs of influenza A virus (IAV)-infected mice. Taken together, our results indicate that VB is a promising therapeutic candidate against IAV infection, complements existing drug limitations targeting viral NA. It modulated the intracellular ROS by G6PD, Nrf2 antioxidant response pathway, and NF-κB signaling pathway. These results demonstrate the feasibility of a multi-targeting drug strategy, providing new approaches for drug discovery against IAV infection.

Antibacterial and Antiviral Properties of Tetrahydrocurcumin-Based Formulations: An Overview of Their Metabolism in Different Microbiotic Compartments

In this review, the basic metabolic characteristics of the curcuminoid tetrahydrocurcumin (THC) at the level of the intestinal microbiota were addressed. Special attention was given to the bactericidal effects of one of the THC-phospholipid formulations, which has shown greater bioavailability and activity than pure THC. Similarly, quinoline derivatives and amino acid conjugates of THC have also shown antibacterial effects in the gut. The microbial effect of pure THC is particularly pronounced in pathophysiological conditions related to the function of the intestinal microbiota, such as type II diabetes. Furthermore, the antiviral characteristics of Cur compared to those of THC are more pronounced in preventing the influenza virus. In the case of HIV infections, the new microemulsion gel formulations of THC possess high retention during preventive application in the vagina and, at the same time, do not disturb the vaginal microbiota, which is critical in maintaining low vaginal pH. Based on the reviewed literature, finding new formulations of THC which can increase its bioavailability and activity and emphasize its antibacterial and antiviral characteristics could be very important. Applying such THC formulations in preventing and treating ailments related to the microbiotic compartments in the body would be beneficial from a medical point of view.

The Contribution of Viral Proteins to the Synergy of Influenza and Bacterial Co-Infection

A severe course of acute respiratory disease caused by influenza A virus (IAV) infection is often linked with subsequent bacterial superinfection, which is difficult to cure. Thus, synergistic influenza-bacterial co-infection represents a serious medical problem. The pathogenic changes in the infected host are accelerated as a consequence of IAV infection, reflecting its impact on the host immune response. IAV infection triggers a complex process linked with the blocking of innate and adaptive immune mechanisms required for effective antiviral defense. Such disbalance of the immune system allows for easier initiation of bacterial superinfection. Therefore, many new studies have emerged that aim to explain why viral-bacterial co-infection can lead to severe respiratory disease with possible fatal outcomes. In this review, we discuss the key role of several IAV proteins-namely, PB1-F2, hemagglutinin (HA), neuraminidase (NA), and NS1-known to play a role in modulating the immune defense of the host, which consequently escalates the development of secondary bacterial infection, most often caused by Streptococcus pneumoniae. Understanding the mechanisms leading to pathological disorders caused by bacterial superinfection after the previous viral infection is important for the development of more effective means of prevention; for example, by vaccination or through therapy using antiviral drugs targeted at critical viral proteins.

Liushen Capsules, a promising clinical candidate for COVID-19, alleviates SARS-CoV-2-induced pulmonary in vivo and inhibits the proliferation of the variant virus strains in vitro

BACKGROUND

Coronavirus disease 2019 (COVID-19) causes a global pandemic and has devastating effects around the world, however, there are no specific antiviral drugs and vaccines for the constant mutation of SARS-CoV-2.

PURPOSE

In this study, we evaluted the antiviral and anti-inflammatory activities of Liushen Capsules (LS) on different novel coronavirus in vitro, studied its therapeutic effects on novel SARS-CoV-2 infected mice and observed the LS's clinical efficacy and safety in COVID-19.

METHODS

The antiviral and aiti-inflammatory effects of LS on the 501Y.V2/B.1.35 and G/478K.V1/ B.1.617.2 strains were determined in vitro. A hACE2 mouse model of novel SARS-CoV-2 pneumonia was established. Survival rates, histological changes, inflammatory markers, lung virus titers and the expression of the key proteins in the NF-κB/MAPK signaling pathway was detected by western blotting and immumohistochemical staining in the lungs were measured. Subsequently, the disease duration, prognosis of disease, time of negative nucleic acid and the cytokines levels in serum were used to assess the efficacy of treatment with LS in patients.

RESULTS

The results showed that LS (2, 1, 0.5 μg/mL) could significantly inhibit the replication of the two SARS-CoV-2 variants and the expression of pro-inflammatory cytokines (IL-6, IL-8, IP-10, CCL-5, MIP-1α, IL-1α) induced by the virus in vitro. As for the survival experiment in mice, the survival rate of virus group was 20%, while LS-treatment groups (40, 80, 160 mg/kg) could increase the survival rate to 60, 100 and 100%, respectively. LS (40, 80, 160 mg/kg) could significantly decrease the lung titers in mice and it could improve the pathological changes, inhibit the excessive inflammatory mediators (IFN-α, IFN-γ, IP-10, MCP-1) and the protein expression of p-NF-κB p65 in mice. Moreover, LS could significantly decrease SARS-CoV-2-induced activation of p-NF-κB p65, p-IκBα, and p-p38 MAPK and increase the protein expression of the IκBα. In addition, the patient got complete relief of symptoms after being treated with LS for 6 days and was proven with negative PCR test after being treated for 23 days. Finally, treatment with LS could reduce the release of inflammatory cytokines (IL-6, PDGF-AA/BB, Eotaxin, MCP-1, MIP-1α, MIP-1β, GRO, CCL-5, MCP-3, IP-10, IL-1α).

CONCLUSION

LS effectively alleviated novel SARS-CoV-2 or variants induced pneumonia in vitro and in vivo, and improved the prognosis of COVID-19. In light of the efficacy and safety profiles, LS could be considered for the treatment of COVID-19 with a broad-spectrum antiviral and anti-inflammatory agent.

Human C1q Regulates Influenza A Virus Infection and Inflammatory Response via Its Globular Domain

The Influenza A virus (IAV) is a severe respiratory pathogen. C1q is the first subcomponent of the complement system's classical pathway. C1q is composed of 18 polypeptide chains. Each of these chains contains a collagen-like region located at the N terminus, and a C-terminal globular head region organized as a heterotrimeric structure (ghA, ghB and ghC). This study was aimed at investigating the complement activation-independent modulation by C1q and its individual recombinant globular heads against IAV infection. The interaction of C1q and its recombinant globular heads with IAV and its purified glycoproteins was examined using direct ELISA and far-Western blotting analysis. The effect of the complement proteins on IAV replication kinetics and immune modulation was assessed by qPCR. The IAV entry inhibitory properties of C1q and its recombinant globular heads were confirmed using cell binding and luciferase reporter assays. C1q bound IAV virions via HA, NA and M1 IAV proteins, and suppressed replication in H1N1, while promoting replication in H3N2-infected A549 cells. C1q treatment further triggered an anti-inflammatory response in H1N1 and pro-inflammatory response in H3N2-infected cells as evident from differential expression of TNF-α, NF-κB, IFN-α, IFN-β, IL-6, IL-12 and RANTES. Furthermore, C1q treatment was found to reduce luciferase reporter activity of MDCK cells transfected with H1N1 pseudotyped lentiviral particles, indicative of an entry inhibitory role of C1q against infectivity of IAV. These data appear to demonstrate the complement-independent subtype specific modulation of IAV infection by locally produced C1q.

Differential miRNA expression profiling of Highly Pathogenic Avian Influenza Virus H5N1 infected chicken lungs reveals critical microRNAs, biological pathways and genes involved in the molecular pathogenesis

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Highthrouput sequencing of small RNA of H5N1 infected and mock infected chicken lungs.

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297 miRNAs identified in mock-infected and 201 miRNAs identified in AIV infected chicken lungs.

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36 miRNAs were upregulated and 90 were downregulated during H5N1 infection.

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Functional analysis and gene ontology of predicted target genes of expressed miRNAs.

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MAPK pathway, NF-κB, IGF and gga-let-7b might play important role during H5N1 pathogenesis.

Human Properdin Released By Infiltrating Neutrophils Can Modulate Influenza A Virus Infection

The complement system is designed to recognise and eliminate invading pathogens via activation of classical, alternative and lectin pathways. Human properdin stabilises the alternative pathway C3 convertase, resulting in an amplification loop that leads to the formation of C5 convertase, thereby acting as a positive regulator of the alternative pathway. It has been noted that human properdin on its own can operate as a pattern recognition receptor and exert immune functions outside its involvement in complement activation. Properdin can bind directly to microbial targets via DNA, sulfatides and glycosaminoglycans, apoptotic cells, nanoparticles, and well-known viral virulence factors. This study was aimed at investigating the complement-independent role of properdin against Influenza A virus infection. As one of the first immune cells to arrive at the site of IAV infection, we show here that IAV challenged neutrophils released properdin in a time-dependent manner. Properdin was found to directly interact with haemagglutinin, neuraminidase and matrix 1 protein Influenza A virus proteins in ELISA and western blot. Furthermore, modelling studies revealed that properdin could bind HA and NA of the H1N1 subtype with higher affinity compared to that of H3N2 due to the presence of an HA cleavage site in H1N1. In an infection assay using A549 cells, properdin suppressed viral replication in pH1N1 subtype while promoting replication of H3N2 subtype, as revealed by qPCR analysis of M1 transcripts. Properdin treatment triggered an anti-inflammatory response in H1N1-challenged A549 cells and a pro-inflammatory response in H3N2-infected cells, as evident from differential mRNA expression of TNF-α, NF-κB, IFN-α, IFN-β, IL-6, IL-12 and RANTES. Properdin treatment also reduced luciferase reporter activity in MDCK cells transduced with H1N1 pseudotyped lentiviral particles; however, it was increased in the case of pseudotyped H3N2 particles. Collectively, we conclude that infiltrating neutrophils at the site of IAV infection can release properdin, which then acts as an entry inhibitor for pandemic H1N1 subtype while suppressing viral replication and inducing an anti-inflammatory response. H3N2 subtype can escape this immune restriction due to altered haemagglutinin and neuraminindase, leading to enhanced viral entry, replication and pro-inflammatory response. Thus, depending on the subtype, properdin can either limit or aggravate IAV infection in the host.

Andrographolide and Its Derivative Potassium Dehydrographolide Succinate Suppress PRRSV Replication in Primary and Established Cells via Differential Mechanisms of Action

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause significant economic loss worldwide and remains a serious threat to the pork industry. Currently, vaccination strategies provide limited protection against PRRSV infection, and consequently, new antiviral strategies are urgently required. Andrographolide (Andro) and its derivative potassium dehydrographolide succinate (PDS) have been used clinically in China and other Asian countries as therapies for inflammation-related diseases, including bacterial and viral infections, for decades. Here, we demonstrate that Andro and PDS exhibit robust activity against PRRSV replication in Marc-145 cells and primary porcine alveolar macrophages (PAMs). The two compounds exhibited broad-spectrum inhibitory activities in vitro against clinically circulating type 2 PRRSV GD-HD, XH-GD, and NADC30-like HNhx strains in China. The EC₅₀ values of Andro against three tested PRRSV strain infections in Marc-145 cells ranged from 11.7 to 15.3 μmol/L, with selectivity indexes ranging from 8.3 to 10.8, while the EC₅₀ values of PDS ranged from 57.1 to 85.4 μmol/L, with selectivity indexes ranging from 344 to 515. Mechanistically, the anti-PRRSV activity of the two compounds is closely associated with their potent suppression on NF-κB activation and enhanced oxidative stress induced by PRRSV infection. Further mechanistic investigations revealed that PDS, but not Andro, is able to directly interact with PRRSV particles. Taken together, our findings suggest that Andro and PDS are promising PRRSV inhibitors in vitro and deserves further in vivo studies in swine.

Transcriptome Analysis of Peripheral Blood Mononuclear Cells Reveals Distinct Immune Response in Asymptomatic and Re-Detectable Positive COVID-19 Patients

The existence of asymptomatic and re-detectable positive coronavirus disease 2019 (COVID-19) patients presents the disease control challenges of COVID-19. Most studies on immune responses in COVID-19 have focused on moderately or severely symptomatic patients; however, little is known about the immune response in asymptomatic and re-detectable positive (RP) patients. Here we performed a comprehensive analysis of the transcriptomic profiles of peripheral blood mononuclear cells (PBMCs) from 48 COVID-19 patients which included 8 asymptomatic, 13 symptomatic, 15 recovered and 12 RP patients. The weighted gene co-expression network analysis (WGCNA) identified six co-expression modules, of which the turquoise module was positively correlated with the asymptomatic, symptomatic, and recovered COVID-19 patients. The red module positively correlated with symptomatic patients only and the blue and brown modules positively correlated with the RP patients. The analysis by single sample gene set enrichment analysis (ssGSEA) revealed a lower level of IFN response and complement activation in the asymptomatic patients compared with the symptomatic, indicating a weaker immune response of the PBMCs in the asymptomatic patients. In addition, gene set enrichment analysis (GSEA) analysis showed the enrichment of TNFα/NF-κB and influenza infection in the RP patients compared with the recovered patients, indicating a hyper-inflammatory immune response in the PBMC of RP patients. Thus our findings could extend our understanding of host immune response during the progression of COVID-19 disease and assist clinical management and the immunotherapy development for COVID-19.

The neuropsychiatric manifestations of COVID-19: Interactions with psychiatric illness and pharmacological treatment

The recent outbreak of the corona virus disease (COVID-19) has had major global impact. The relationship between severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection and psychiatric diseases is of great concern, with an evident link between corona virus infections and various central and peripheral nervous system manifestations. Unmitigated neuro-inflammation has been noted to underlie not only the severe respiratory complications of the disease but is also present in a range of neuro-psychiatric illnesses. Several neurological and psychiatric disorders are characterized by immune-inflammatory states, while treatments for these disorders have distinct anti-inflammatory properties and effects. With inflammation being a common contributing factor in SARS-CoV-2, as well as psychiatric disorders, treatment of either condition may affect disease progression of the other or alter response to pharmacological treatment. In this review, we elucidate how viral infections could affect pre-existing psychiatric conditions and how pharmacological treatments of these conditions may affect overall progress and outcome in the treatment of SARS-CoV-2. We address whether any treatment-induced benefits and potential adverse effects may ultimately affect the overall treatment approach, considering the underlying dysregulated neuro-inflammatory processes and potential drug interactions. Finally, we suggest adjunctive treatment options for SARS-CoV-2-associated neuro-psychiatric symptoms.

San Wu Huangqin decoction regulates inflammation and immune dysfunction induced by influenza virus by regulating the NF-κB signaling pathway in H1N1-infected mice

ETHNOPHARMACOLOGICAL RELEVANCE

The San Wu Huangqin Decoction (SWHD), which is made from the dried root of Sophora flavescens Aiton (Kushen in Chinese), the dried root of Scutellaria baicalensis Georgi (Huangqin in Chinese), and the dried root tuber of Rehmannia glutinosa (Gaertn.) DC. (Dihuang in Chinese), is a traditional Chinese formula used to treat prolonged fever and inflammatory diseases in clinics and proven to inhibit influenza virus effectively in our previous study.

AIM OF THE STUDY

This work was performed to study the regulation of SWHD on inflammation and immune dysfunction induced by the influenza virus and the underlying mechanism in the treatment of SWHD.

METHODS

In this study, the influenza virus A/PR/8/34 (H1N1)-infected mouse model was used to investigate the regulation of SWHD on inflammation and immune dysfunction induced by H1N1. The pathological changes, the capacity of proliferation of T and B lymphocytes, the cytotoxicity of natural killer (NK) cells, and the levels of IL-6, TNF-α, IL-1β, IL-4, and IFN-γ in the serum, bronchoalveolar lavage fluid (BALF), and lung were analyzed. The effects of type 1 T helper cell (Th1) and type 2 T helper cell (Th2) immune responses were discussed indirectly. In addition, the expression levels of p-p65, p65, IKKα/β, p-IκBα, and IκBα in relation to the NF-κB pathway were measured using Western blot analysis, or immunohistochemical assay.

RESULTS

SWHD decreased the pathological changes in lung tissues, promoted the proliferation of T and B lymphocytes, enhanced NK cell activity, and accelerated the phagocytic function of macrophages in H1N1-infected mice. At the same time, SWHD decreased the levels of IL-6, TNF-α, IL-1β, IFN-γ, and increased the level of IL-4 in the serum, BALF, and lung of model mice. Moreover, the p-p65, p65, and IκBα protein expression levels were inhibited, whereas the p-IκBα protein expression levels were improved in the lungs of H1N1-infected mice.

CONCLUSIONS

SWHD can inhibit the replication of the H1N1 virus and reduced the excessive inflammation and immune dysfunction induced by the H1N1 virus in the body. This work provides rich experimental basis for further anti-inflammation research of SWHD and sets the foundation for the development of a viral inflammation drug of traditional Chinese medicine.

Taming the cytokine storm: repurposing montelukast for the attenuation and prophylaxis of severe COVID-19 symptoms

As a result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, a clinical complication can arise that is characterized by a hyperinflammatory cytokine profile, often termed a 'cytokine storm'. A protein complex (nuclear factor kappa-light-chain-enhancer of activated B cells; NF-κB) is intricately involved in regulating inflammation and the immune response following viral infections, with a reduction in cytokine production often observed following a decrease in NF-κB activity. An approved asthma drug, montelukast, has been found to modulate the activity of NF-κB, and result in a corresponding decrease in proinflammatory mediators. Herein, we hypothesize that repurposing montelukast to suppress NF-κB activation will result in an attenuation of proinflammatory mediators and a decrease in cytokine production, thereby leading to a reduction in symptom severity and to improved clinical outcomes in patients with Coronavirus 2019 (COVID-19).

MicroRNA-206 inhibits influenza A virus replication by targeting tankyrase 2

Due to the frequent mutations, influenza A virus (IAV) becomes resistant to anti-viral drugs targeting influenza viral proteins. There are increasing interests in anti-viral agents that target host cellular proteins required for virus replication. Tankyrase (TNKS) has poly (ADP-ribose) polymerase activity and is a negative regulator of many host proteins. The objectives of this study are to study the role of TNKS2 in IAV infection, identify the microRNAs targeting TNKS2, and to understand the mechanisms involved. We found that TNKS2 expression was elevated in human lung epithelial cells and mouse lungs during IAV infection. Knock-down of TNKS2 by RNA interference reduced viral replication. Using a computation approach and 3'-untranslation regions (3'-UTR) reporter assay, we identified miR-206 as the microRNA that targeted TNKS2. Overexpression of miR-206 reduced viral protein levels and virus production in cell culture. The effect of miR-206 on IAV replication was strain-independent. miR-206 activated JNK/c-Jun signalling, induced type I interferon expression and enhanced Stat signalling. Finally, the delivery of an adenovirus expressing miR-206 into the lung of mice challenged with IAV increased type I interferon response, suppressed viral load in the lungs and increased survival. Our results indicate that miR-206 has anti-influenza activity by targeting TNKS2 and subsequently activating the anti-viral state.

Consensus transcriptional regulatory networks of coronavirus-infected human cells

Establishing consensus around the transcriptional interface between coronavirus (CoV) infection and human cellular signaling pathways can catalyze the development of novel anti-CoV therapeutics. Here, we used publicly archived transcriptomic datasets to compute consensus regulatory signatures, or consensomes, that rank human genes based on their rates of differential expression in MERS-CoV (MERS), SARS-CoV-1 (SARS1) and SARS-CoV-2 (SARS2)-infected cells. Validating the CoV consensomes, we show that high confidence transcriptional targets (HCTs) of MERS, SARS1 and SARS2 infection intersect with HCTs of signaling pathway nodes with known roles in CoV infection. Among a series of novel use cases, we gather evidence for hypotheses that SARS2 infection efficiently represses E2F family HCTs encoding key drivers of DNA replication and the cell cycle; that progesterone receptor signaling antagonizes SARS2-induced inflammatory signaling in the airway epithelium; and that SARS2 HCTs are enriched for genes involved in epithelial to mesenchymal transition. The CoV infection consensomes and HCT intersection analyses are freely accessible through the Signaling Pathways Project knowledgebase, and as Cytoscape-style networks in the Network Data Exchange repository.

PA-X protein of H5N1 avian influenza virus inhibits NF-kappaB activity, a potential mechanism for PA-X counteracting the host innate immune responses

PA-X is a fusion protein of influenza virus which plays a crucial role in modulating influenza virus-induced host innate immune response and subsequent pathogenicity. However, the potential mechanism of PA-X regulation of the host innate immune response remains largely unknown. It is well known that NF-κB signal pathway is crucial for the immediate early step of immune responses activation, while the specific role of PA-X in NF-κB transcriptional activity is totally unknown. In this study, we initially showed that PA-X inhibits NF-κB transcription that stimulated by poly(I:C). We then further determined that the inhibitory effect on NF-κB activation mediated by PA-X was characterized by restricting NF-κB p65 nuclear translocation and nuclear NF-κB p65 activity but not by impeding the phosphorylation of NF-κB p65. Correspondingly, PA-X decreases the amount of NF-κB signaling pathway-associated genes, including TNF-α, Nos2, IL-6 and IL-2. Moreover, PA-X also suppresses both the mRNA and protein expression level of IFN-β, suggesting the direct contribution of PA-X to the inhibition of NF-κB-regulated IFN-β expression. Together, our study sheds light on the potential molecular mechanisms underlying the regulation of host NF-κB activity by PA-X and also identifies a novel functional role for PA-X in counteracting the host innate immune response. However, further exploration of the more elaborate mechanism of PA-X-mediated inhibition of NF-κB activity and the associated signaling pathway may help to elucidate its precise mechanism of evading and subverting the host immune response.

Single-Cell Sequencing of Peripheral Mononuclear Cells Reveals Distinct Immune Response Landscapes of COVID-19 and Influenza Patients

The coronavirus disease 2019 (COVID-19) pandemic poses a current world-wide public health threat. However, little is known about its hallmarks compared to other infectious diseases. Here, we report the single-cell transcriptional landscape of longitudinally collected peripheral blood mononuclear cells (PBMCs) in both COVID-19- and influenza A virus (IAV)-infected patients. We observed increase of plasma cells in both COVID-19 and IAV patients and XIAP associated factor 1 (XAF1)-, tumor necrosis factor (TNF)-, and FAS-induced T cell apoptosis in COVID-19 patients. Further analyses revealed distinct signaling pathways activated in COVID-19 (STAT1 and IRF3) versus IAV (STAT3 and NFκB) patients and substantial differences in the expression of key factors. These factors include relatively increase of interleukin (IL)6R and IL6ST expression in COVID-19 patients but similarly increased IL-6 concentrations compared to IAV patients, supporting the clinical observations of increased proinflammatory cytokines in COVID-19 patients. Thus, we provide the landscape of PBMCs and unveil distinct immune response pathways in COVID-19 and IAV patients.

Consensus transcriptional regulatory networks of coronavirus-infected human cells

Establishing consensus around the transcriptional interface between coronavirus (CoV) infection and human cellular signaling pathways can catalyze the development of novel anti-CoV therapeutics. Here, we used publicly archived transcriptomic datasets to compute consensus regulatory signatures, or consensomes, that rank human genes based on their rates of differential expression in MERS-CoV (MERS), SARS-CoV-1 (SARS1) and SARS-CoV-2 (SARS2)-infected cells. Validating the CoV consensomes, we show that high confidence transcriptional targets (HCTs) of CoV infection intersect with HCTs of signaling pathway nodes with known roles in CoV infection. Among a series of novel use cases, we gather evidence for hypotheses that SARS2 infection efficiently represses E2F family target genes encoding key drivers of DNA replication and the cell cycle; that progesterone receptor signaling antagonizes SARS2-induced inflammatory signaling in the airway epithelium; and that SARS2 HCTs are enriched for genes involved in epithelial to mesenchymal transition. The CoV infection consensomes and HCT intersection analyses are freely accessible through the Signaling Pathways Project knowledgebase, and as Cytoscape-style networks in the Network Data Exchange repository.

AML1 protein interacts with influenza A virus neuraminidase and upregulates IFN-β response in infected mammalian cells

Neuraminidase (NA) is an integral membrane protein of influenza A virus (IAV) and primarily aids in the release of progeny virions, following the intracellular viral replication cycle. In an attempt to discover new functions of NA, we conducted a classical yeast two-hybrid screen and found acute myeloid leukaemia marker 1 (AML1) as a novel interacting partner of IAV-NA. The interaction was further validated by co-immunoprecipitation in IAV-infected cells and in an in vitro coupled transcription/translation system. Interestingly, we found an increase in the expression of AML1 upon IAV infection in a dose-dependent manner. As expected, we also observed an increase in the IFN-β levels, the first line of defence against viral infections. Subsequently, when AML1 was downregulated using siRNA, the IFN-β levels were found to be remarkably reduced. Our study also shows that AML1 is induced upon IAV infection and results in the induction of IFN-β. Thus, AML1 is proposed to be an important player in IFN induction and has a role in an antiviral response against IAV infection. SIGNIFICANCE AND IMPACT OF THE STUDY: Influenza epidemics and pandemics are constant threats to human health. Development of antiviral therapeutics has focused on important and major IAV proteins as targets. However, the rate at which this virus mutates makes the task challenging. Thus, next-generation approaches aim at host cellular proteins that aid the virus in its replication. This study reports a new host-virus interaction, of acute myeloid leukaemia marker 1 (AML1) with influenza A neuraminidase (IAV-NA). We have found that this interaction has a direct effect on the upregulation of host IFN-β response. Further studies may lead to a greater understanding of this new innate defence pathway in infected cells.

C4b Binding Protein Acts as an Innate Immune Effector Against Influenza A Virus

C4b Binding Protein (C4BP) is a major fluid phase inhibitor of the classical and lectin pathways of the complement system. Complement inhibition is achieved by binding to and restricting the role of activated complement component C4b. C4BP functions as a co-factor for factor I in proteolytic inactivation of both soluble and cell surface-bound C4b, thus restricting the formation of the C3-convertase, C4b2a. C4BP also accelerates the natural decay/dissociation of the C3 convertase. This makes C4BP a prime target for exploitation by pathogens to escape complement attack, as seen in Streptococcus pyogenes or Flavivirus. Here, we examined whether C4BP can act on its own in a complement independent manner, against pathogens. C4BP bound H1N1 and H3N2 subtypes of Influenza A Virus (IAV) most likely via multiple sites in Complement Control Protein (CCP) 1-2, 4-5, and 7-8 domains of its α-chain. In addition, C4BP CCP1-2 bound H3N2 better than H1N1. C4BP bound three IAV envelope proteins: Haemagglutinin (~70 kDa), Neuraminidase (~55 kDa), and Matrix protein 1 (~25kDa). C4BP suppressed H1N1 subtype infection into the lung epithelial cell line, A549, while it promoted infection by H3N2 subtype. C4BP restricted viral entry for H1N1 but had the opposite effect on H3N2, as evident from experiments using pseudo-typed viral particles. C4BP downregulated mRNA levels of pro-inflammatory IFN-α, IL-12, and NFκB in the case of H1N1, while it promoted a pro-inflammatory immune response by upregulating IFN- α, TNF-α, RANTES, and IL-6 in the case of H3N2. We conclude that C4BP differentially modulates the efficacy of IAV entry, and hence, replication in a target cell in a strain-dependent manner, and acts as an entry inhibitor for H1N1. Thus, CCP containing complement proteins such as factor H and C4BP may have additional defense roles against IAV that do not rely on the regulation of complement activation.

Microarray Gene Expression Dataset Re-analysis Reveals Variability in Influenza Infection and Vaccination

Influenza, a communicable disease, affects thousands of people worldwide. Young children, elderly, immunocompromised individuals and pregnant women are at higher risk for being infected by the influenza virus. Our study aims to highlight differentially expressed genes in influenza disease compared to influenza vaccination, including variability due to age and sex. To accomplish our goals, we conducted a meta-analysis using publicly available microarray expression data. Our inclusion criteria included subjects with influenza, subjects who received the influenza vaccine and healthy controls. We curated 18 microarray datasets for a total of 3,481 samples (1,277 controls, 297 influenza infection, 1,907 influenza vaccination). We pre-processed the raw microarray expression data in R using packages available to pre-process Affymetrix and Illumina microarray platforms. We used a Box-Cox power transformation of the data prior to our down-stream analysis to identify differentially expressed genes. Statistical analyses were based on linear mixed effects model with all study factors and successive likelihood ratio tests (LRT) to identify differentially-expressed genes. We filtered LRT results by disease (Bonferroni adjusted p < 0.05) and used a two-tailed 10% quantile cutoff to identify biologically significant genes. Furthermore, we assessed age and sex effects on the disease genes by filtering for genes with a statistically significant (Bonferroni adjusted p < 0.05) interaction between disease and age, and disease and sex. We identified 4,889 statistically significant genes when we filtered the LRT results by disease factor, and gene enrichment analysis (gene ontology and pathways) included innate immune response, viral process, defense response to virus, Hematopoietic cell lineage and NF-kappa B signaling pathway. Our quantile filtered gene lists comprised of 978 genes each associated with influenza infection and vaccination. We also identified 907 and 48 genes with statistically significant (Bonferroni adjusted p < 0.05) disease-age and disease-sex interactions, respectively. Our meta-analysis approach highlights key gene signatures and their associated pathways for both influenza infection and vaccination. We also were able to identify genes with an age and sex effect. This gives potential for improving current vaccines and exploring genes that are expressed equally across ages when considering universal vaccinations for influenza.

Investigating the Cellular Transcriptomic Response Induced by the Makona Variant of Ebola Virus in Differentiated THP-1 Cells

Recent studies have shown that transcriptomic analysis of blood samples taken from patients with acute Ebola virus disease (EVD) during the 2013–2016 West African outbreak was suggestive that a severe inflammatory response took place in acutely ill patients. The significant knowledge gained from studying the Makona variant, a cause of the largest known EVD outbreak, may be applicable to other species of ebolavirus, and other variants of the Ebola virus (EBOV) species. To investigate the ability of Makona to initiate an inflammatory response in human macrophages and characterise the host response in a similar manner to previously characterised EBOV variants, the human monocytic cell line THP-1 was differentiated into macrophage-like cells and infected with Makona. RNA-Seq and quantitative proteomics were used to identify and quantify host mRNA and protein abundance during infection. Data from infection with Reston virus (RESTV) were used as comparators to investigate changes that may be specific to, or enhanced in, Makona infection in relation to a less pathogenic species of ebolavirus.. This study found demonstrable induction of the inflammatory response, and increase in the activation state of THP-1 macrophages infected with Makona. NFκB and inflammation-associated transcripts displayed significant changes in abundance, reflective of what was observed in human patients during the 2013–2016 EBOV outbreak in West Africa, and demonstrated that transcriptomic changes found in Makona-infected cells were similar to that observed in Reston virus infection and that have been described in previous studies of other variants of EBOV.

A dual controllability analysis of influenza virus-host protein-protein interaction networks for antiviral drug target discovery

BACKGROUND

Host factors of influenza virus replication are often found in key topological positions within protein-protein interaction networks. This work explores how protein states can be manipulated through controllability analysis: the determination of the minimum manipulation needed to drive the cell system to any desired state. Here, we complete a two-part controllability analysis of two protein networks: a host network representing the healthy cell state and an influenza A virus-host network representing the infected cell state. In this context, controllability analyses aim to identify key regulating host factors of the infected cell's progression. This knowledge can be utilized in further biological analysis to understand disease dynamics and isolate proteins for study as drug target candidates.

RESULTS

Both topological and controllability analyses provide evidence of wide-reaching network effects stemming from the addition of viral-host protein interactions. Virus interacting and driver host proteins are significant both topologically and in controllability, therefore playing important roles in cell behavior during infection. Functional analysis finds overlap of results with previous siRNA studies of host factors involved in influenza replication, NF-kB pathway and infection relevance, and roles as interferon regulating genes. 24 proteins are identified as holding regulatory roles specific to the infected cell by measures of topology, controllability, and functional role. These proteins are recommended for further study as potential antiviral drug targets.

CONCLUSIONS

Seasonal outbreaks of influenza A virus are a major cause of illness and death around the world each year with a constant threat of pandemic infection. This research aims to increase the efficiency of antiviral drug target discovery using existing protein-protein interaction data and network analysis methods. These results are beneficial to future studies of influenza virus, both experimental and computational, and provide evidence that the combination of topology and controllability analyses may be valuable for future efforts in drug target discovery.

Sodium ferulate protects against influenza virus infection by activation of the TLR7/9-MyD88-IRF7 signaling pathway and inhibition of the NF-κB signaling pathway

Influenza A virus (IAV) is highly contagious and causes considerable mortality worldwide. TLR3, 7, 8 and 9 recognize viral nucleic acids and rapidly trigger different signaling cascades that contribute to the production of interferons (IFNs) to antiviral defense. Therefore, a host immune response induced by the activation of these receptors can be used as a new antiviral strategy. In this study, the protective effect of sodium ferulate (SF) is investigated on mice infected with influenza virus A/FM/1/47(H1N1). SF improved survival and mitigated weight loss in infected mice. SF inhibited influenza virus replication by activating TLR7 and TLR9, which resulted in the promotion of IRF7 translocation into the nucleus and the production of typeⅠIFNs. Moreover, SF inhibited the NF-κB pathway by preventing p65 translocation from the cytoplasm to the nucleus. These findings demonstrate that SF plays a critical role in protection against IAV infection by activation of the TLR7/9-MyD88-IRF7 signaling pathway and inhibition of the NF-κB signaling pathway.

Repurposing host-based therapeutics to control coronavirus and influenza virus

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Drug repositioning is a cost- and time-efficient approach for new indications.

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Targeting host machineries, used by viruses, could develop broad-spectrum antivirals.

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Repurposing existing drugs could efficiently identify antiviral agents.

The development of highly effective antiviral agents has been a major objective in virology and pharmaceutics. Drug repositioning has emerged as a cost-effective and time-efficient alternative approach to traditional drug discovery and development. This new shift focuses on the repurposing of clinically approved drugs and promising preclinical drug candidates for the therapeutic development of host-based antiviral agents to control diseases caused by coronavirus and influenza virus. Host-based antiviral agents target host cellular machineries essential for viral infections or innate immune responses to interfere with viral pathogenesis. This review discusses current knowledge, prospective applications and challenges in the repurposing of clinically approved and preclinically studied drugs for newly indicated antiviral therapeutics.

miR-193b represses influenza A virus infection by inhibiting Wnt/β-catenin signalling

Due to an increasing emergence of new and drug‐resistant strains of the influenza A virus (IAV), developing novel measures to combat influenza is necessary. We have previously shown that inhibiting Wnt/β‐catenin pathway reduces IAV infection. In this study, we aimed to identify antiviral human microRNAs (miRNAs) that target the Wnt/β‐catenin signalling pathway. Using a miRNA expression library, we identified 85 miRNAs that up‐regulated and 20 miRNAs that down‐regulated the Wnt/β‐catenin signalling pathway. Fifteen miRNAs were validated to up‐regulate and five miRNAs to down‐regulate the pathway. Overexpression of four selected miRNAs (miR‐193b, miR‐548f‐1, miR‐1‐1, and miR‐509‐1) that down‐regulated the Wnt/β‐catenin signalling pathway reduced viral mRNA, protein levels in A/PR/8/34‐infected HEK293 cells, and progeny virus production. Overexpression of miR‐193b in lung epithelial A549 cells also resulted in decreases of A/PR/8/34 infection. Furthermore, miR‐193b inhibited the replication of various strains, including H1N1 (A/PR/8/34, A/WSN/33, A/Oklahoma/3052/09) and H3N2 (A/Oklahoma/309/2006), as determined by a viral reporter luciferase assay. Further studies revealed that β‐catenin was a target of miR‐193b, and β‐catenin rescued miR‐193b‐mediated suppression of IAV infection. miR‐193b induced G0/G1 cell cycle arrest and delayed vRNP nuclear import. Finally, adenovirus‐mediated gene transfer of miR‐193b to the lung reduced viral load in mice challenged by a sublethal dose of A/PR/8/34. Collectively, our findings suggest that miR‐193b represses IAV infection by inhibiting Wnt/β‐catenin signalling.

(+)‑pinoresinol‑O‑β‑D‑glucopyranoside from Eucommia ulmoides Oliver and its anti‑inflammatory and antiviral effects against influenza A (H1N1) virus infection

Eucommia ulmoides Oliver (Du-Zhong) is an ancient Chinese herbal remedy used for the treatment of various diseases. To date, the effects of its constituent lignans on influenza viruses remain to be elucidated. In the present study, a lignan glycoside was isolated and purified from Eucommia ulmoides Oliver. Its structures were identified via extensive spectroscopic analysis, and its antiviral and anti‑inflammatory activities, specifically against influenza viruses, were determined via a cytopathic effect (CPE) assay, plaque‑reduction assays, a progeny virus yield reduction assay, reverse transcription‑quantitative polymerase chain reaction analysis and a Luminex assay. Additionally, western blot analysis was performed to investigate the underlying mechanisms of its effects against influenza viruses. The chemical and spectroscopic methods determined the structure of lignan glycoside to be (+)‑pinoresinol‑O‑β‑D‑glucopyranoside. The CPE assay showed that (+)‑pinoresinol‑O‑β‑D‑glucopyranoside exerted inhibitory activities with 50% inhibition concentration values of 408.81±5.24 and 176.24±4.41 µg/ml against the influenza A/PR/8/34 (H1N1) and A/Guangzhou/GIRD07/09 (H1N1) strains, respectively. Its antiviral properties were confirmed by plaque reduction and progeny virus yield reduction assays. Additional mechanistic analyses indicated that the anti‑H1N1 virus‑induced effects of (+)‑pinoresinol‑O-β‑D-glucopyranoside were likely due to inactivation of the nuclear factor‑κB, p38 mitogen‑activated protein kinase and AKT signaling pathways. Furthermore, (+)‑pinoresinol‑O‑β‑D‑glucopyranoside exhibited pronounced inhibitory effects on the expression of influenza H1N1 virus‑induced pro‑inflammatory mediators, including tumor necrosis factor‑α, interleukin (IL)‑6, IL‑8 and monocyte chemoattractant protein 1. The data obtained suggest that (+)‑pinoresinol‑O‑β‑D-glucopyranoside may be a candidate drug for treating influenza H1N1 virus infection.

Houttuynia cordata polysaccharides ameliorate pneumonia severity and intestinal injury in mice with influenza virus infection

ETHNOPHARMACOLOGICAL RELEVANCE

Hottuynia cordata is an important traditional Chinese medicine for the treatment of respiratory diseases including bacterial and viral infections. Polysaccharides isolated from Houttuynia cordata (HCP), as its main ingredients, have been demonstrated to ameliorate the LPS-induced acute lung injury in mice. The study aimed to determine the protective effects of HCP on multiple organ injury in influenza A virus (IAV) H1N1 infected mice and its primary mechanisms in anti-inflammation and immune regulation.

MATERIALS AND METHODS

Mice were inoculated with IAV H1N1 and then treated with 20 or 40 mg/kg/d of HCP for survival test and acute lung-gut injury test.

RESULTS

The treatment with HCP resulted in an increase in the survival rate of H1N1 infected mice and the protection from lung and intestine injury, accompanied with the reduced virus replication. HCP markedly decreased the concentration of pulmonary proinflammatory cytokines/chemokines and the number of intestinal goblet cells, and strengthened the intestinal physical and immune barrier, according to the increase of sIgA and tight junction protein (ZO-1) in intestine. At the same time, the inhibition of inflammation in lung and gut was related to the suppressing of the expression of TLR4 and p-NFκB p65 in lung.

CONCLUSIONS

These results indicated that HCP ameliorated lung and intestine injury induced by IAV attack. The mechanisms were associated with inhibition of inflammation, protection of intestinal barrier and regulation of mucosal immunity, which may be related to the regulation of gut-lung axis. As an alternative medicine, HCP may have clinical potential to treat IAV infection in human beings.

N-myc downstream-regulated gene 1 facilitates influenza A virus replication by suppressing canonical NF-κB signaling

The highly pathogenic avian influenza (HPAI) A/H5N1 virus hijacks host cellular machinery to complete its life cycle; identification of the host factors involved in viral replication may facilitate antiviral drug development. Here, we first characterize a metastasis suppressor, N-myc downstream-regulated gene 1 (NDRG1), and showed that it plays a crucial role in H5N1 viral replication. We found that H5N1 infection upregulated NDRG1 mRNA and protein expression. Overexpression of NDRG1 released approximately 4-fold more virions compared to the control group, whereas knockdown of NDRG1 resulted in a drop in viral RNA and protein production. Further investigation revealed that NDRG1 facilitated HPAI A/H5N1 viral replication by suppressing the canonical NF-κB signaling pathway. Furthermore, our results also showed that the NDRG1 mRNA level was mainly stimulated by M1 and PB1 viral proteins. Overall, our results suggest that NDRG1 plays a positive role in HPAI replication by suppressing the canonical NF-κB signaling pathway.

Targeting intracellular signaling as an antiviral strategy: aerosolized LASAG for the treatment of influenza in hospitalized patients

Influenza has been a long-running health problem and novel antiviral drugs are urgently needed. In pre-clinical studies, we demonstrated broad antiviral activity of D, L-lysine-acetylsalicylate glycine (LASAG) against influenza virus (IV) in cell culture and protection against lethal challenge in mice. LASAG is a compound with a new antiviral mode of action. It inhibits the NF-κB signal transduction module that is essential for IV replication. Our goal was to determine whether aerosolized LASAG would also show a therapeutic benefit in hospitalized patients suffering from severe influenza. The primary endpoint was time to alleviation of clinical influenza symptoms. The primary analysis was based on the modified intention-to-treat (MITT) population. This included all patients with confirmed influenza virus infection who received at least one treatment. The per protocol (PP) analysis set included all subjects from the MITT population who underwent at least 13 inhalations. In the MITT group, 48 (41.7%) participants (29 LASAG; 19 placebo) had severe influenza. The mean time to symptom alleviation was 56.2 h in the placebo group and 43.0 h in the LASAG group. The PP set consisted of 41 patients (24 LASAG; 17 placebo). The mean time to symptom alleviation in the LASAG group (38.3 h; P = 0.0365) was lower than that in the placebo group (56.2 h). In conclusion, LASAG improved the time to alleviation of influenza symptoms in hospitalized patients. The present phase II proof-of-concept (PoC) study demonstrates that targeting an intra-cellular signaling pathway using aerosolized LASAG improves the time to symptom alleviation compared to standard treatment.

Influenza A viruses alter the stability and antiviral contribution of host E3-ubiquitin ligase Mdm2 during the time-course of infection

The interplay between influenza A viruses (IAV) and the p53 pathway has been reported in several studies, highlighting the antiviral contribution of p53. Here, we investigated the impact of IAV on the E3-ubiquitin ligase Mdm2, a major regulator of p53, and observed that IAV targets Mdm2, notably via its non-structural protein (NS1), therefore altering Mdm2 stability, p53/Mdm2 interaction and regulatory loop during the time-course of infection. This study also highlights a new antiviral facet of Mdm2 possibly increasing the list of its many p53-independent functions. Altogether, our work contributes to better understand the mechanisms underlining the complex interactions between IAV and the p53 pathway, for which both NS1 and Mdm2 arise as key players.

MERS-CoV 4b protein interferes with the NF-κB-dependent innate immune response during infection

Middle East respiratory syndrome coronavirus (MERS-CoV) is a novel human coronavirus that emerged in 2012, causing severe pneumonia and acute respiratory distress syndrome (ARDS), with a case fatality rate of ~36%. When expressed in isolation, CoV accessory proteins have been shown to interfere with innate antiviral signaling pathways. However, there is limited information on the specific contribution of MERS-CoV accessory protein 4b to the repression of the innate antiviral response in the context of infection. We found that MERS-CoV 4b was required to prevent a robust NF-κB dependent response during infection. In wild-type virus infected cells, 4b localized to the nucleus, while NF-κB was retained in the cytoplasm. In contrast, in the absence of 4b or in the presence of cytoplasmic 4b mutants lacking a nuclear localization signal (NLS), NF-κB was translocated to the nucleus leading to the expression of pro-inflammatory cytokines. This indicates that NF-κB repression required the nuclear import of 4b mediated by a specific NLS. Interestingly, we also found that both in isolation and during infection, 4b interacted with α-karyopherin proteins in an NLS-dependent manner. In particular, 4b had a strong preference for binding karyopherin-α4 (KPNA4), which is known to translocate the NF-κB protein complex into the nucleus. Binding of 4b to KPNA4 during infection inhibited its interaction with NF-κB-p65 subunit. Thereby we propose a model where 4b outcompetes NF-κB for KPNA4 binding and translocation into the nucleus as a mechanism of interference with the NF-κB-mediated innate immune response.

Pharmacodynamics, Pharmacokinetics, and Antiviral Activity of BAY 81-8781, a Novel NF-κB Inhibiting Anti-influenza Drug

Influenza is a respiratory disease that causes annual epidemics. Antiviral treatment options targeting the virus exist, but their efficiency is limited and influenza virus strains easily develop resistance. Thus, new treatment strategies are urgently needed. In the present study, we investigated the anti-influenza virus properties of D,L-lysine acetylsalicylate ⋅ glycine (BAY 81-8781; LASAG) that is approved as Aspirin i.v. for intravenous application. Instead of targeting the virus directly BAY 81-8781 inhibits the activation of the NF-κB pathway, which is required for efficient influenza virus propagation. Using highly pathogenic avian influenza virus strains we could demonstrate that BAY 81-8781 was able to control influenza virus infection in vitro. In the mouse infection model, inhalation of BAY 81-8781 resulted in reduced lung virus titers and protection of mice from lethal infection. Pharmacological studies demonstrated that the oral route of administration was not suitable to reach the sufficient concentrations of BAY 81-8781 for a successful antiviral effect in the lung. BAY 81-8781 treatment of mice infected with influenza virus started as late as 48 h after infection was still effective in protecting 50% of the animals from death. In summary, the data represent a successful proof of the novel innovative antiviral concept of targeting a host cell signaling pathway that is required for viral propagation instead of viral structures.

Pterodontic Acid Isolated from Laggera pterodonta Inhibits Viral Replication and Inflammation Induced by Influenza A Virus

Laggera pterodonta (DC.) Benth. is a traditional Chinese medicine. The previous study revealed that the crude extracts of this herb could inhibit influenza virus infection, but its anti-influenza components and underlying mechanism of action remain unknown. Column chromatography was performed to isolate components from the plant. Activity against influenza virus of the compound was determined by CPE inhibition assay. Neuraminidase (NA) inhibition was measured by chemiluminescence assay. The anti-virus and anti-inflammation effects were determined using dual-luciferase reporter assay, immunofluorescence, quantitative real-time PCR and luminex assay. Pterodontic acid was isolated from L. pterodonta, which showed selective anti-viral activities to H1 subtype of human influenza A virus. Meanwhile, the NA activity was not obviously inhibited by the compound. Further experiments exhibited that the compound can suppress the activation of NF-κB signal pathway and export of viral RNP complexes from the nucleus. In addition, it can significantly attenuate expression of the pro-inflammatory molecules IL-6, MIP-1β, MCP-1, and IP-10 induced by human influenza A virus (H1N1) and similarly downregulate expression of cytokines and chemokines induced by avian influenza A virus (H9N2). This study showed that in vitro antiviral activity of pterodontic acid is most probably associated with inhibiting the replication of influenza A virus by blocking nuclear export of viral RNP complexes, and attenuating the inflammatory response by inhibiting activation of the NF-κB pathway. Pterodontic acid might be a potential antiviral agent against influenza A virus.

Association between oral health and upper respiratory tract infection among children

BACKGROUND

The oral cavity is a potential reservoir for respiratory pathogens. This longitudinal study investigated the association between upper respiratory tract infection (URI) and oral health among children.

METHODS

A total of 288 children aged 4 years were recruited. Their dental caries and oral hygiene status were clinically determined, using the dmft (decayed, missing and filled teeth) index and the Silness-Löe plaque index. Questionnaires were completed by parents to collect information on the child's socio-demographic background and URI episodes and symptoms in the following 12 months. Standard or zero-inflated negative binomial regressions were used to analyse the association between URI and both oral health indicators (dmft and plaque score).

RESULTS

Some 138 (47.9%) children had URI in 12 months, including 63 (21.9%) and 75 (26.0%) children with 1-2 episodes and ≥3 episodes, respectively. The reported URI episodes fell into two peaks, coinciding with the two influenza peaks in Hong Kong. Significantly a higher dmft was found among children without URI compared with children who had ≥3 URI episodes (1.32 vs. 0.49; P = 0.043). The number of URI episodes was inversely associated with dmft (IRR = 0.851; 95% CI: 0.766-0.945; P = 0.003). There was no significant association between the plaque score and URI (P > 0.05).

CONCLUSIONS

The children's caries experience was associated with reduced episodes of URI. Whether this inverse association is attributed to the immune response induced by dental caries is yet to be investigated.

Broad-Range Antiviral Activity of Hydrogen Sulfide Against Highly Pathogenic RNA Viruses

Hydrogen sulfide is an important endogenous mediator that has been the focus of intense investigation in the past few years, leading to the discovery of its role in vasoactive, cytoprotective and anti-inflammatory responses. Recently, we made a critical observation that H₂S also has a protective role in paramyxovirus infection by modulating inflammatory responses and viral replication. In this study we tested the antiviral and anti-inflammatory activity of the H₂S slow-releasing donor GYY4137 on enveloped RNA viruses from Ortho-, Filo-, Flavi- and Bunyavirus families, for which there is no FDA-approved vaccine or therapeutic available, with the exception of influenza. We found that GYY4137 significantly reduced replication of all tested viruses. In a model of influenza infection, GYY4137 treatment was associated with decreased expression of viral proteins and mRNA, suggesting inhibition of an early step of replication. The antiviral activity coincided with the decrease of viral-induced pro-inflammatory mediators and viral-induced nuclear translocation of transcription factors from Nuclear Factor (NF)-kB and Interferon Regulatory Factor families. In conclusion, increasing cellular H₂S is associated with significant antiviral activity against a broad range of emerging enveloped RNA viruses, and should be further explored as potential therapeutic approach in relevant preclinical models of viral infections.

Carbon Monoxide Inhibits Porcine Reproductive and Respiratory Syndrome Virus Replication by the Cyclic GMP/Protein Kinase G and NF-κB Signaling Pathway

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the pork industry worldwide each year. Our previous research demonstrated that heme oxygenase-1 (HO-1) can suppress PRRSV replication via an unknown molecular mechanism. In this study, inhibition of PRRSV replication was demonstrated to be mediated by carbon monoxide (CO), a downstream metabolite of HO-1. Using several approaches, we demonstrate that CO significantly inhibited PRRSV replication in both a PRRSV permissive cell line, MARC-145, and the predominant cell type targeted during in vivo PRRSV infection, porcine alveolar macrophages (PAMs). Our results showed that CO inhibited intercellular spread of PRRSV; however, it did not affect PRRSV entry into host cells. Furthermore, CO was found to suppress PRRSV replication via the activation of the cyclic GMP/protein kinase G (cGMP/PKG) signaling pathway. CO significantly inhibits PRRSV-induced NF-κB activation, a required step for PRRSV replication. Moreover, CO significantly reduced PRRSV-induced proinflammatory cytokine mRNA levels. In conclusion, the present study demonstrates that CO exerts its anti-PRRSV effect by activating the cellular cGMP/PKG signaling pathway and by negatively regulating cellular NF-κB signaling. These findings not only provide new insights into the molecular mechanism of HO-1 inhibition of PRRSV replication but also suggest potential new control measures for future PRRSV outbreaks.

IMPORTANCE

PRRSV causes great economic losses each year to the swine industry worldwide. Carbon monoxide (CO), a metabolite of HO-1, has been shown to have antimicrobial and antiviral activities in infected cells. Our previous research demonstrated that HO-1 can suppress PRRSV replication. Here we show that endogenous CO produced through HO-1 catalysis mediates the antiviral effect of HO-1. CO inhibits PRRSV replication by activating the cellular cGMP/PKG signaling pathway and by negatively regulating cellular NF-κB signaling. These findings not only provide new insights into the molecular mechanism of HO-1 inhibition of PRRSV replication but also suggest potential new control measures for future PRRSV outbreaks.

Distinct immune responses of juvenile and adult oysters (Crassostrea gigas) to viral and bacterial infections

Since 2008, massive mortality events of Pacific oysters (Crassostrea gigas) have been reported worldwide and these disease events are often associated with Ostreid herpesvirus type 1 (OsHV-1). Epidemiological field studies have also reported oyster age and other pathogens of the Vibrio genus are contributing factors to this syndrome. We undertook a controlled laboratory experiment to simultaneously investigate survival and immunological response of juvenile and adult C. gigas at different time-points post-infection with OsHV-1, Vibrio tasmaniensis LGP32 and V. aestuarianus. Our data corroborates epidemiological studies that juveniles are more susceptible to OsHV-1, whereas adults are more susceptible to Vibrio. We measured the expression of 102 immune-genes by high-throughput RT-qPCR, which revealed oysters have different transcriptional responses to OsHV-1 and Vibrio. The transcriptional response in the early stages of OsHV-1 infection involved genes related to apoptosis and the interferon-pathway. Transcriptional response to Vibrio infection involved antimicrobial peptides, heat shock proteins and galectins. Interestingly, oysters in the later stages of OsHV-1 infection had a transcriptional response that resembled an antibacterial response, which is suggestive of the oyster’s microbiome causing secondary infections (dysbiosis-driven pathology). This study provides molecular evidence that oysters can mount distinct immune response to viral and bacterial pathogens and these responses differ depending on the age of the host.

Comparing the functions of equine and canine influenza H3N8 virus PA-X proteins: Suppression of reporter gene expression and modulation of global host gene expression

The influenza PA-X protein is translated from the PA open reading frame from frameshifting and suppresses cellular gene expression due to its ribonuclease activity. We further defined the functional roles of PA-X by comparing PA-X proteins from two related viruses - equine influenza (EIV) and canine influenza (CIV) H3N8 - that differ in a C-terminal truncation and internal mutations. In vitro reporter gene assays revealed that both proteins were able to suppress gene expression. Interestingly, EIV PA-X demonstrated ~50% greater activity compared to CIV PA-X, and we identified the mutations that caused this difference. We used RNA-seq to evaluate the effects of PA-X on host gene expression after transfection into cultured cells. There were no significant differences in this property between EIV and CIV PA-X proteins, but expression of either resulted in the up-regulation of genes when compared to controls, most notably immunity-related proteins, trafficking proteins, and transcription factors.

Identification of miRNomes reveals ssc-miR-30d-R_1 as a potential therapeutic target for PRRS viral infection

Porcine reproductive and respiratory syndrome virus (PRRSV) is known to cause reproductive disorders, such as abortion, in pregnant sows as well as immunosuppressive respiratory complications, leading to severe respiratory tract infections in young pigs. In this study, an in-depth analysis of the miRNomes in mock- and virus-infected pig lungs was carried out. We found that highly expressed ssc-miR-30d-R_1 was decreased in infected lungs, and reduced levels were significantly correlated with infection by PRRSV. Moreover, ssc-miR-30d-R_1 was shown to target Toll-like receptor 4 (TLR4) and to suppress the production of immune cytokines through inhibition of the TLR4/MyD88/NF-κB pathway. ssc-miR-30d-R_1 significantly reduced viral infections and pathological changes in pig lungs in vivo. Our current study reveals the miRNomes of PRRSV-infected pig lungs and indicates that ssc-miR-30d-R_1 is potential therapeutic agent for controlling PRRSV infection.

Chemical Genomics Identifies the PERK-Mediated Unfolded Protein Stress Response as a Cellular Target for Influenza Virus Inhibition

Influenza A viruses generate annual epidemics and occasional pandemics of respiratory disease with important consequences for human health and the economy. Therefore, a large effort has been devoted to the development of new anti-influenza virus drugs directed to viral targets, as well as to the identification of cellular targets amenable to anti-influenza virus therapy. Here we have addressed the identification of such potential cellular targets by screening collections of drugs approved for human use. We reasoned that screening with a green fluorescent protein-based recombinant replicon system would identify cellular targets involved in virus transcription/replication and/or gene expression and hence address an early stage of virus infection. By using such a strategy, we identified Montelukast (MK) as an inhibitor of virus multiplication. MK inhibited virus gene expression but did not alter viral RNA synthesis in vitro or viral RNA accumulation in vivo. The low selectivity index of MK prevented its use as an antiviral, but it was sufficient to identify a new cellular pathway suitable for anti-influenza virus intervention. By deep sequencing of RNA isolated from mock- and virus-infected human cells, treated with MK or left untreated, we showed that it stimulates the PERK-mediated unfolded protein stress response. The phosphorylation of PERK was partly inhibited in virus-infected cells but stimulated in MK-treated cells. Accordingly, pharmacological inhibition of PERK phosphorylation led to increased viral gene expression, while inhibition of PERK phosphatase reduced viral protein synthesis. These results suggest the PERK-mediated unfolded protein response as a potential cellular target to modulate influenza virus infection.

Influenza A viruses are responsible for annual epidemics and occasional pandemics with important consequences for human health and the economy. The unfolded protein response is a defense mechanism fired by cells when the demand of protein synthesis and folding is excessive, for instance, during an acute virus infection. In this report, we show that influenza virus downregulates the unfolded protein response mediated by the PERK sensor, while Montelukast, a drug used to treat asthma in humans, specifically stimulated this response and downregulated viral protein synthesis and multiplication. Accordingly, we show that PERK phosphorylation was reduced in virus-infected cells and increased in cells treated with Montelukast. Hence, our studies suggest that modulation of the PERK-mediated unfolded protein response is a target for influenza virus inhibition.

Influenza A Virus and Influenza B Virus Can Induce Apoptosis via Intrinsic or Extrinsic Pathways and Also via NF-κB in a Time and Dose Dependent Manner

Influenza viruses are able to cause annual epidemics and pandemics due to their mutation rates and reassortment capabilities leading to antigenic shifts and drifts. To identify host response to influenza A and B viruses on A549 and MDCK II cells at low and high MOIs, expressions of MxA and caspases 3, 8, and 9 and BAD, TNFα, and IκBα genes were measured in the cells supernatants. H1N1 and H3N2 prefer to initially enhance the intrinsic pathway, determined by higher caspase 9 activity in MDCK II cells compared to caspase 8 activity and vice versa in A549 cells at different MOIs, while INF B prefers extrinsic pathway in A549 cells according to significant low or undetectable caspase 9 activity and high activity of caspase 8 but also can induce intrinsic pathway in MDCK II cells as determined by significant low or undetectable activity of caspase 8 and high caspase 9 activity at different MOIs; the considerable MxA expression was found in influenza A and B viruses infected A549 and MDCK II cells at low MOIs. In conclusion, influenza A and B viruses induced extrinsic and intrinsic apoptosis in parallel, and the induction was associated with viral infection in a dose dependent manner.

Anti-inflammatory effect of thalidomide on H1N1 influenza virus-induced pulmonary injury in mice

The purpose of this study is to investigate the anti-inflammatory effect of thalidomide (Thd) on H1N1-induced acute lung injury in mice. BALB/C mice were infected intranasally with influenza A virus (H1N1) and then treated with Thd at a dose of 100 or 200 mg/kg/day for 7 days. Weight loss and survival of mice were monitored for 14 days after virus challenge, and the serum and lung tissues were collected at 4 days for histological and biochemical analysis. The results showed that Thd significantly improved the survival rate, reduced the infiltration of inflammatory cells and cytokine (e.g., IL-6, TNF-α) and chemokine (e.g., RANTES, IP-10) levels, and inhibited activated p-NFκB p65 in infected mice. These findings suggested that Thd may attenuate H1N1-induced pulmonary injury and thus may find use in the treatment of viral diseases.

Broad-spectrum antiviral agents

Development of highly effective, broad-spectrum antiviral agents is the major objective shared by the fields of virology and pharmaceutics. Antiviral drug development has focused on targeting viral entry and replication, as well as modulating cellular defense system. High throughput screening of molecules, genetic engineering of peptides, and functional screening of agents have identified promising candidates for development of optimal broad-spectrum antiviral agents to intervene in viral infection and control viral epidemics. This review discusses current knowledge, prospective applications, opportunities, and challenges in the development of broad-spectrum antiviral agents.

Distinct kinetics and pathways of apoptosis in influenza A and B virus infection

Annual influenza epidemics are associated with high incidence and mortality rates, and are an important cause of work absenteeism and productivity losses. For successful replication, influenza viruses have evolved as to counteract and/or take a part on host defense mechanisms. Manipulation of apoptosis is one of such mechanisms that have been subject of attention, particularly in relation to influenza type A viruses over the past years. However, this knowledge has not been extended to include influenza type B viruses. In this study, MDCK-SIAT1 cells were infected with influenza A and B strains and the kinetics and pathways of apoptosis post infection were studied, through LDH measurements, Hoechst dye staining, caspase activity assays and protein expression analysis. The resulting data points to a difference in induction of apoptosis profiles between influenza A and B strains. While influenza A strain induced apoptosis later in the course of infection and mainly by the intrinsic pathway, influenza B strain induced apoptosis early in infection by both intrinsic and extrinsic pathways. Also, data revealed the IκB/NF-κB pathway as the major contributor for the observed differences. The study of the virus-host interactions, particularly those that could have an impact on viral replication, are essential in both influenza A and B viruses, as they will allow the identification of viral/host targets common to both influenza types, which could affect viral replication. This information may prove useful for vaccine and antiviral research.

The roles of endoplasmic reticulum overload response induced by HCV and NS4B protein in human hepatocyte viability and virus replication

Hepatitis C virus (HCV) replication is associated with endoplasmic reticulum (ER) and its infection triggers ER stress. In response to ER stress, ER overload response (EOR) can be activated, which involves the release of Ca²⁺ from ER, production of reactive oxygen species (ROS) and activation of nuclear factor κB (NF-κB). We have previously reported that HCV NS4B expression activates NF-κB via EOR-Ca²⁺-ROS pathway. Here, we showed that NS4B expression and HCV infection activated cancer-related NF-κB signaling pathway and induced the expression of cancer-related NF-κB target genes via EOR-Ca²⁺-ROS pathway. Moreover, we found that HCV-activated EOR-Ca²⁺-ROS pathway had profound effects on host cell viability and HCV replication. HCV infection induced human hepatocyte death by EOR-Ca²⁺-ROS pathway, whereas activation of EOR-Ca²⁺-ROS-NF-κB pathway increased the cell viability. Meanwhile, EOR-Ca²⁺-ROS-NF-κB pathway inhibited acute HCV replication, which could alleviate the detrimental effect of HCV on cell viability and enhance chronic HCV infection. Together, our findings provide new insights into the functions of EOR-Ca²⁺-ROS-NF-κB pathway in natural HCV replication and pathogenesis.