Vemurafenib Limits Influenza A Virus Propagation by Targeting Multiple Signaling Pathways

Vemurafenib inhibits the replication of diabetogenic enteroviruses in intestinal epithelial and pancreatic beta cells

Enteroviruses, which infect via the gut, have been implicated in type 1 diabetes (T1D) development. Prolonged faecal shedding of enterovirus has been associated with islet autoimmunity. Additionally, enteroviral proteins and viral RNA have been detected in the pancreatic islets of individuals with recent-onset T1D, implicating their possible role in beta cell destruction. Despite this, no approved antiviral drugs currently exist that specifically target enterovirus infections for utilisation in disease interventions. Drug repurposing allows for the discovery of new clinical uses for existing drugs and can expedite drug discovery. Previously, the cancer drug Vemurafenib demonstrated unprecedented antiviral activity against several enteroviruses. In the present study, we assessed the efficacy of Vemurafenib and an analogue thereof in preventing infection or reducing the replication of enteroviruses associated with T1D. We tested Vemurafenib in intestinal epithelial cells (IECs) and insulin-producing beta cells. Additionally, we established a protocol for infecting human stem cell-derived islets (SC-islets) and used Vemurafenib and its analogue in this model. Our studies revealed that Vemurafenib exhibited strong antiviral properties in IECs and a beta cell line. The antiviral effect was also seen with the Vemurafenib analogue. SC-islets expressed the viral receptors CAR and DAF, with their highest expression in insulin- and glucagon-positive cells, respectively. SC-islets were successfully infected by CVBs and the antiviral activity of Vemurafenib and its analogue was confirmed in most SC-islet batches. In summary, our observations suggest that Vemurafenib and its analogue warrant further exploration as potential antiviral agents for the treatment of enterovirus-induced diseases, including T1D.

Functions of MAP3Ks in antiviral immunity

Immune signal transduction is crucial to the body's defense against viral infection. Recognition of pathogen-associated molecular patterns by pattern recognition receptors (PRRs) activates the transcription of interferon regulators and nuclear factor-κB (NF-κB); this promotes the release of interferons and inflammatory factors. Efficient regulation of type I interferon and NF-κB signaling by members of the mitogen-activated protein (MAP) kinase kinase kinase (MAP3K) family plays an important role in antiviral immunity. Elucidating the specific roles of MAP3K activation during viral infection is essential to develop effective antiviral therapies. In this review, we outline the specific regulatory mechanisms of MAP3Ks in antiviral immunity and discuss the feasibility of targeting MAP3Ks for the treatment of virus-induced diseases.

Vemurafenib Inhibits Acute and Chronic Enterovirus Infection by Affecting Cellular Kinase Phosphatidylinositol 4-Kinase Type IIIβ

Enteroviruses are one of the most abundant viruses causing mild to serious acute infections in humans and also contributing to chronic diseases like type 1 diabetes. Presently, there are no approved antiviral drugs against enteroviruses. Here, we studied the potency of vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, as an antiviral against enteroviruses. We showed that vemurafenib prevented enterovirus translation and replication at low micromolar dosage in an RAF/MEK/ERK-independent manner. Vemurafenib was effective against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect was related to a cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevented infection efficiently in acute cell models, eradicated infection in a chronic cell model, and lowered virus amounts in pancreas and heart in an acute mouse model. Altogether, instead of acting through the RAF/MEK/ERK pathway, vemurafenib affects the cellular PI4KB and, hence, enterovirus replication, opening new possibilities to evaluate further the potential of vemurafenib as a repurposed drug in clinical care. IMPORTANCE Despite the prevalence and medical threat of enteroviruses, presently, there are no antivirals against them. Here, we show that vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, prevents enterovirus translation and replication. Vemurafenib shows efficacy against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect acts through cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevents infection efficiently in acute cell models, eradicates infection in a chronic cell model, and lowers virus amounts in pancreas and heart in an acute mouse model. Our findings open new possibilities to develop drugs against enteroviruses and give hope for repurposing vemurafenib as an antiviral drug against enteroviruses.

Discovery of SARS-CoV-2 antiviral synergy between remdesivir and approved drugs in human lung cells

SARS coronavirus 2 (SARS-CoV-2) has caused an ongoing global pandemic with significant mortality and morbidity. At this time, the only FDA-approved therapeutic for COVID-19 is remdesivir, a broad-spectrum antiviral nucleoside analog. Efficacy is only moderate, and improved treatment strategies are urgently needed. To accomplish this goal, we devised a strategy to identify compounds that act synergistically with remdesivir in preventing SARS-CoV-2 replication. We conducted combinatorial high-throughput screening in the presence of submaximal remdesivir concentrations, using a human lung epithelial cell line infected with a clinical isolate of SARS-CoV-2. This identified 20 approved drugs that act synergistically with remdesivir, many with favorable pharmacokinetic and safety profiles. Strongest effects were observed with established antivirals, Hepatitis C virus nonstructural protein 5A (HCV NS5A) inhibitors velpatasvir and elbasvir. Combination with their partner drugs sofosbuvir and grazoprevir further increased efficacy, increasing remdesivir's apparent potency > 25-fold. We report that HCV NS5A inhibitors act on the SARS-CoV-2 exonuclease proofreader, providing a possible explanation for the synergy observed with nucleoside analog remdesivir. FDA-approved Hepatitis C therapeutics Epclusa® (velpatasvir/sofosbuvir) and Zepatier® (elbasvir/grazoprevir) could be further optimized to achieve potency and pharmacokinetic properties that support clinical evaluation in combination with remdesivir.

FDA-Approved Inhibitors of RTK/Raf Signaling Potently Impair Multiple Steps of In Vitro and Ex Vivo Influenza A Virus Infections

Influenza virus (IV) infections pose a burden on global public health with significant morbidity and mortality. The limited range of currently licensed IV antiviral drugs is susceptible to the rapid rise of resistant viruses. In contrast, FDA-approved kinase inhibitors can be repurposed as fast-tracked host-targeted antivirals with a higher barrier of resistance. Extending our recent studies, we screened 21 FDA-approved small-molecule kinase inhibitors (SMKIs) and identified seven candidates as potent inhibitors of pandemic and seasonal IV infections. These SMKIs were further validated in a biologically and clinically relevant ex vivo model of human precision-cut lung slices. We identified steps of the virus infection cycle affected by these inhibitors (entry, replication, egress) and found that most SMKIs affected both entry and egress. Based on defined and overlapping targets of these inhibitors, the candidate SMKIs target receptor tyrosine kinase (RTK)-mediated activation of Raf/MEK/ERK pathways to limit influenza A virus infection. Our data and the established safety profiles of these SMKIs support further clinical investigations and repurposing of these SMKIs as host-targeted influenza therapeutics.

Vemurafenib Inhibits Enterovirus A71 Genome Replication and Virus Assembly

Enterovirus A71 (EV-A71) infection is a major cause of hand, foot, and mouth disease (HFMD), which may be occasionally associated with severe neurological complications. There is currently a lack of treatment options for EV-A71 infection. The Raf-MEK-ERK signaling pathway, in addition to its critical importance in the regulation of cell growth, differentiation, and survival, has been shown to be essential for virus replication. In this study, we investigated the anti-EV-A71 activity of vemurafenib, a clinically approved B-Raf inhibitor used in the treatment of late-stage melanoma. Vemurafenib exhibits potent anti-EV-A71 effect in cytopathic effect inhibition and viral load reduction assays, with half maximal effective concentration (EC50) at nanomolar concentrations. Mechanistically, vemurafenib interrupts both EV-A71 genome replication and assembly. These findings expand the list of potential antiviral candidates of anti-EV-A71 therapeutics.

Bioinformatics and System Biology Approach to Reveal the Interaction Network and the Therapeutic Implications for Non-Small Cell Lung Cancer Patients With COVID-19

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the leading cause of coronavirus disease-2019 (COVID-19), is an emerging global health crisis. Lung cancer patients are at a higher risk of COVID-19 infection. With the increasing number of non-small-cell lung cancer (NSCLC) patients with COVID-19, there is an urgent need of efficacious drugs for the treatment of COVID-19/NSCLC.

Methods: Based on a comprehensive bioinformatic and systemic biological analysis, this study investigated COVID-19/NSCLC interactional hub genes, detected common pathways and molecular biomarkers, and predicted potential agents for COVID-19 and NSCLC.

Results: A total of 122 COVID-19/NSCLC interactional genes and 21 interactional hub genes were identified. The enrichment analysis indicated that COVID-19 and NSCLC shared common signaling pathways, including cell cycle, viral carcinogenesis, and p53 signaling pathway. In total, 10 important transcription factors (TFs) and 44 microRNAs (miRNAs) participated in regulations of 21 interactional hub genes. In addition, 23 potential candidates were predicted for the treatment of COVID-19 and NSCLC.

Conclusion: This study increased our understanding of pathophysiology and screened potential drugs for COVID-19 and NSCLC.

Cellular Protein Phosphatase 2A Regulates Cell Survival Mechanisms in Influenza A Virus Infection

Influenza A viruses (IAVs) are respiratory pathogens that are able to hijack multiple cellular mechanisms to drive their replication. Consequently, several viral and cellular proteins undergo posttranslational modifications such as dynamic phosphorylation/dephosphorylation. In eukaryotic cells, dephosphorylation is mainly catalyzed by protein phosphatase 2A (PP2A). While the function of kinases in IAV infection is quite well studied, only little is known about the role of PP2A in IAV replication. Here, we show, by using knockdown and inhibition approaches of the catalytic subunit PP2Ac, that this phosphatase is important for efficient replication of several IAV subtypes. This could neither be attributed to alterations in the antiviral immune response nor to changes in transcription or translation of viral genes. Interestingly, decreased PP2Ac levels resulted in a significantly reduced cell viability after IAV infection. Comprehensive kinase activity profiling identified an enrichment of process networks related to apoptosis and indicated a synergistic action of hyper-activated PI3K/Akt, MAPK/JAK-STAT and NF-kB signaling pathways, collectively resulting in increased cell death. Taken together, while IAV seems to effectively tap leftover PP2A activity to ensure efficient viral replication, reduced PP2Ac levels fail to orchestrate cell survival mechanisms to protect infected cells from early cell death.

Evidence that two instead of one defective interfering RNA in influenza A virus-derived defective interfering particles (DIPs) does not enhance antiviral activity

Influenza A virus (IAV) infection constitutes a significant health threat. Defective interfering particles (DIPs) can arise during IAV infection and inhibit spread of wild type (WT) IAV. DIPs harbor defective RNA segments, termed DI RNAs, that usually contain internal deletions and interfere with replication of WT viral RNA segments. Here, we asked whether DIPs harboring two instead of one DI RNA exert increased antiviral activity. For this, we focused on DI RNAs derived from segments 1 and 3, which encode the polymerase subunits PB2 and PA, respectively. We demonstrate the successful production of DIPs harboring deletions in segments 1 and/or 3, using cell lines that co-express PB2 and PA. Further, we demonstrate that DIPs harboring two instead of one DI RNA do not exhibit increased ability to inhibit replication of a WT RNA segment. Similarly, the presence of two DI RNAs did not augment the induction of the interferon-stimulated gene MxA and the inhibition of IAV infection. Collectively, our findings suggest that the presence of multiple DI RNAs derived from genomic segments encoding polymerase subunits might not result in increased antiviral activity.

Phosphorylation of JIP4 at S730 Presents Antiviral Properties against Influenza A Virus Infection

Influenza A virus (IAV) is the causative agent of flu disease that results in annual epidemics and occasional pandemics. IAV alters several signaling pathways of the cellular host response in order to promote its replication. Therefore, some of these pathways can serve as targets for novel antiviral agents. Here, we show that c-Jun NH2-terminal kinase (JNK)-interacting protein 4 (JIP4) is dynamically phosphorylated in IAV infection. The lack of JIP4 resulted in higher virus titers, with significant differences in viral protein and mRNA accumulation as early as within the first replication cycle. In accordance, decreased IAV titers and protein accumulation were observed during the overexpression of JIP4. Strikingly, the antiviral function of JIP4 does not originate from modulation of JNK or p38 mitogen-activated protein kinase (MAPK) pathways or from altered expression of interferons or interferon-stimulated genes but rather originates from a direct reduction of viral polymerase activity. Furthermore, the interference of JIP4 with IAV replication seems to be linked to the phosphorylation of the serine at position 730 that is sufficient to impede the viral polymerase. Collectively, we provide evidence that JIP4, a host protein modulated in IAV infection, exhibits antiviral properties that are dynamically controlled by its phosphorylation at S730. IMPORTANCE Influenza A virus (IAV) infection is a world health concern, and current treatment options encounter high rates of resistance. Our group investigates host pathways modified in IAV infection as promising new targets. The host protein JIP4 is dynamically phosphorylated in IAV infection. JIP4 absence resulted in higher virus titers and viral protein and mRNA accumulation within the first replication cycle. Accordingly, decreased IAV titers and protein accumulation were observed during JIP4 overexpression. Strikingly, the antiviral function of JIP4 does not originate from modulation of JNK or p38 MAPK pathways or from altered expression of interferons or interferon-stimulated genes but rather originates from a reduction in viral polymerase activity. The interference of JIP4 with IAV replication is linked to the phosphorylation of serine 730. We provide evidence that JIP4, a host protein modulated in IAV infection, exhibits antiviral properties that are dynamically controlled by its phosphorylation at S730.

Immunizations in immunocompromised patients: a guide for dermatologists

The increasingly frequent use of immunomodulatory agents in dermatology requires the observance of specific recommendations for immunization. These recommendations are developed and regularly updated by the German Standing Committee on Vaccination (STIKO), an independent advisory group at the Robert Koch Institute. Dermatological patients on immunosuppressive treatment should ideally receive all vaccinations included in the standard immunization schedule. Additionally, it is recommended that they also undergo vaccination against the seasonal flu, pneumococci, and herpes zoster (inactivated herpes zoster subunit vaccine for patients ≥ 50 years). Additional immunizations against Haemophilus influenzae type B, hepatitis B and meningococci may be indicated depending on individual comorbidities and exposure risk. Limitations of use, specific contraindications and intervals to be observed between vaccination and immunosuppression depend on the immunosuppressive agent used and its dosing. Only under certain conditions may live-attenuated vaccines be administered in patients on immunosuppressive therapy. Given its strong suppressive effect on the humoral immune response, no vaccines - except for flu shots - should be given within six months after rituximab therapy. This CME article presents current recommendations on immunization in immunocompromised individuals, with a special focus on dermatological patients. Its goal is to enable readers to provide competent counseling and to initiate necessary immunizations in this vulnerable patient group.

Regulation of Host Immune Responses against Influenza A Virus Infection by Mitogen-Activated Protein Kinases (MAPKs)

Influenza is a major respiratory viral disease caused by infections from the influenza A virus (IAV) that persists across various seasonal outbreaks globally each year. Host immune response is a key factor determining disease severity of influenza infection, presenting an attractive target for the development of novel therapies for treatments. Among the multiple signal transduction pathways regulating the host immune activation and function in response to IAV infections, the mitogen-activated protein kinase (MAPK) pathways are important signalling axes, downstream of various pattern recognition receptors (PRRs), activated by IAVs that regulate various cellular processes in immune cells of both innate and adaptive immunity. Moreover, aberrant MAPK activation underpins overexuberant production of inflammatory mediators, promoting the development of the “cytokine storm”, a characteristic of severe respiratory viral diseases. Therefore, elucidation of the regulatory roles of MAPK in immune responses against IAVs is not only essential for understanding the pathogenesis of severe influenza, but also critical for developing MAPK-dependent therapies for treatment of respiratory viral diseases. In this review, we will summarise the current understanding of MAPK functions in both innate and adaptive immune response against IAVs and discuss their contributions towards the cytokine storm caused by highly pathogenic influenza viruses.

Host-Directed Antiviral Therapy

Antiviral drugs have traditionally been developed by directly targeting essential viral components. However, this strategy often fails due to the rapid generation of drug-resistant viruses. Recent genome-wide approaches, such as those employing small interfering RNA (siRNA) or clustered regularly interspaced short palindromic repeats (CRISPR) or those using small molecule chemical inhibitors targeting the cellular "kinome," have been used successfully to identify cellular factors that can support virus replication. Since some of these cellular factors are critical for virus replication, but are dispensable for the host, they can serve as novel targets for antiviral drug development. In addition, potentiation of immune responses, regulation of cytokine storms, and modulation of epigenetic changes upon virus infections are also feasible approaches to control infections. Because it is less likely that viruses will mutate to replace missing cellular functions, the chance of generating drug-resistant mutants with host-targeted inhibitor approaches is minimized. However, drug resistance against some host-directed agents can, in fact, occur under certain circumstances, such as long-term selection pressure of a host-directed antiviral agent that can allow the virus the opportunity to adapt to use an alternate host factor or to alter its affinity toward the target that confers resistance. This review describes novel approaches for antiviral drug development with a focus on host-directed therapies and the potential mechanisms that may account for the acquisition of antiviral drug resistance against host-directed agents.

Influenza virus entry via the GM3 ganglioside-mediated platelet-derived growth factor receptor β signalling pathway

The possible resistance of influenza virus against existing antiviral drugs calls for new therapeutic concepts. One appealing strategy is to inhibit virus entry, in particular at the stage of internalization. This requires a better understanding of virus-host interactions during the entry process, including the role of receptor tyrosine kinases (RTKs). To search for cellular targets, we evaluated a panel of 276 protein kinase inhibitors in a multicycle antiviral assay in Madin-Darby canine kidney cells. The RTK inhibitor Ki8751 displayed robust anti-influenza A and B virus activity and was selected for mechanistic investigations. Ki8751 efficiently disrupted the endocytic process of influenza virus in different cell lines carrying platelet-derived growth factor receptor β (PDGFRβ), an RTK that is known to act at GM3 ganglioside-positive lipid rafts. The more efficient virus entry in CHO-K1 cells compared to the wild-type ancestor (CHO-wt) cells indicated a positive effect of GM3, which is abundant in CHO-K1 but not in CHO-wt cells. Entering virus localized to GM3-positive lipid rafts and the PDGFRβ-containing endosomal compartment. PDGFRβ/GM3-dependent virus internalization involved PDGFRβ phosphorylation, which was potently inhibited by Ki8751, and desialylation of activated PDGFRβ by the viral neuraminidase. Virus uptake coincided with strong activation of the Raf/MEK/Erk cascade, but not of PI3K/Akt or phospholipase C-γ. We conclude that influenza virus efficiently hijacks the GM3-enhanced PDGFRβ signalling pathway for cell penetration, providing an opportunity for host cell-targeting antiviral intervention.

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.

Metabolic conversion of CI-1040 turns a cellular MEK-inhibitor into an antibacterial compound

Influenza virus (IV) infections cause severe respiratory illnesses that can be complicated by bacterial super-infections. Previously, we identified the cellular Raf-MEK-ERK cascade as a promising antiviral target. Inhibitors of MEK, such as CI-1040, showed potent antiviral activity. However, it remained unclear if this inhibitor and its active form, ATR-002, might sensitize host cells to either IV or secondary bacterial infections. To address these questions, we studied the anti-pathogen activity of ATR-002 in comparison to CI-1040, particularly, its impact on Staphylococcus aureus (S. aureus), which is a major cause of IV super-infections. We analysed IV and S. aureus titres in vitro during super-infection in the presence and absence of the drugs and characterized the direct impact of ATR-002 on bacterial growth and phenotypic changes. Importantly, neither CI-1040 nor ATR-002 treatment led to increased bacterial titres during super-infection, indicating that the drug does not sensitize cells for bacterial infection. In contrast, we rather observed reduced bacterial titres in presence of ATR-002. Surprisingly, ATR-002 also led to reduced bacterial growth in suspension cultures, reduced stress- and antibiotic tolerance without resistance induction. Our data identified for the first time that a particular MEK-inhibitor metabolite exhibits direct antibacterial activity, which is likely due to interference with the bacterial PknB kinase/Stp phosphatase signalling system.

Role of MAPK/MNK1 signaling in virus replication

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Viruses are known to exploit cellular signaling pathways.

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MAPK is a major cell signaling pathway activated by diverse group of viruses.

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MNK1 regulates both cap-dependent and IRES-mediated mRNA translation.

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This review discuss the role of MAPK, particularly the role of MNK1 in virus replication.

Viruses are obligate intracellular parasites; they heavily depend on the host cell machinery to effectively replicate and produce new progeny virus particles. Following viral infection, diverse cell signaling pathways are initiated by the cells, with the major goal of establishing an antiviral state. However, viruses have been shown to exploit cellular signaling pathways for their own effective replication. Genome-wide siRNA screens have also identified numerous host factors that either support (proviral) or inhibit (antiviral) virus replication. Some of the host factors might be dispensable for the host but may be critical for virus replication; therefore such cellular factors may serve as targets for development of antiviral therapeutics. Mitogen activated protein kinase (MAPK) is a major cell signaling pathway that is known to be activated by diverse group of viruses. MAPK interacting kinase 1 (MNK1) has been shown to regulate both cap-dependent and internal ribosomal entry sites (IRES)-mediated mRNA translation. In this review we have discuss the role of MAPK in virus replication, particularly the role of MNK1 in replication and translation of viral genome.

An active component containing pterodontic acid and pterodondiol isolated from Laggera pterodonta inhibits influenza A virus infection through the TLR7/MyD88/TRAF6/NF‑κB signaling pathway

The influenza virus is a pathogen that can cause pandemic and epidemic outbreaks, and therefore represents a severe threat to human health. Antiviral drugs have an important role in the prevention and treatment of influenza, although the increasing emergence of drug resistance has given rise to a requirement for the development of novel antiviral drugs. In the present study, an active component (C8) isolated from Laggera pterodonta was evaluated. The nuclear magnetic resonance spectroscopy and mass spectrometry analysis results revealed that two eudesmane‑type sesquiterpene compounds were identified in C8; pterodontic acid and pterodondiol. C8 was demonstrated to have a broad‑spectrum effect against different influenza viruses, including human and avian influenza viruses, with a half maximal inhibitory concentration value of 19.9‑91.4 µg/ml. The antiviral mechanisms of C8 were further clarified. Western blot analysis verified that C8 inhibited Toll‑like receptor 7, myeloid differentiation primary response protein 88 and tumor necrosis factor (TNF) receptor associated factor 6 expression, in addition to p65 phosphorylation, at a concentration of 100 or 150 µg/ml. An indirect immunofluorescence assay demonstrated that C8 may inhibit p65/NF‑κB nuclear translocation. Additionally, C8 prevented an increase in cytokine mRNA expression, including interleukin (IL)‑1β, IL‑6, IL‑8 and C‑C motif chemokine 2 (MCP‑1). Furthermore, the Bio‑Plex assay results indicated that the protein expression of IL‑6, IL‑8, TNF‑α, C‑X‑C motif chemokine 10, MCP‑1 and C‑C motif chemokine 5 was inhibited. These findings suggest that C8 has the potential to be developed into an anti‑inflammatory drug for the prevention and treatment of influenza A virus infection.