Inhibition of adenovirus infection by mifepristone

In vitro assessment of the anti-adenoviral activity of artemisinin and its derivatives

Adenoviral infections, particularly in children, remain a significant public health issue with no approved targeted treatments. Artemisinin and its derivatives, well-known for their use in malaria treatment, have shown antiviral activities in recent studies. However, their efficacy against human adenovirus (HAdV) remains unexplored. This study aimed to assess the activity of artemisinin and its derivatives against HAdV infection in vitro using cell lines and primary cells. Our data revealed that artemisinin exhibited dose-dependent anti-HAdV activity with no apparent cytotoxicity over a wide concentration range. Mechanistically, artemisinin did not affect viral attachment or entry into target cells, nor the viral genome entry into cell nucleus. Instead, it inhibited HAdV through suppression of viral DNA replication. Comparative analysis with its derivatives, artesunate and artemisone, showed distinct cytotoxicity and anti-adenoviral profiles, with artemisone showing superior efficacy and lower toxicity. Further validation using a primary airway epithelial cell model confirmed the anti-adenoviral activity of both artemisinin and artemisone against different virus strains. Together, our findings suggest that artemisinin and its derivatives may be promising candidates for anti-HAdV treatment.

Current antiviral agents against human adenoviruses associated with respiratory infections

Human adenoviruses (HAdVs) are important pathogens responsible for respiratory infections. In children and immunocompromised patients, respiratory infections can cause considerable morbidity and mortality. Currently, there are no approved effective and safe antiviral therapeutics for the clinical treatment of HAdV infections, even those that have undergone preclinical/clinical trials. However, many compounds and molecules with anti-HAdV activity have been explored, and some candidates are undergoing clinical development. Here, we reviewed the reported in vitro and in vivo efficacies, as well as the therapeutic potential of these antiviral compounds, providing an overview and a summary of the current status of anti-HAdV drug development.

Inhibition of adenovirus transport from the endosome to the cell nucleus by rotenone

Regardless of the clinical impact of human adenovirus (HAdV) infections in the healthy population and its high morbidity in immunosuppressed patients, a specific treatment is still not yet available. In this study, we screened the CM1407 COST Action's chemical library, comprising 1,233 natural products to identify compounds that restrict HAdV infection. Among them, we identified rotenolone, a compound that significantly inhibited HAdV infection. Next, we selected four isoflavonoid-type compounds (e.g., rotenone, deguelin, millettone, and tephrosin), namely rotenoids, structurally related to rotenolone in order to evaluate and characterized in vitro their antiviral activities against HAdV and human cytomegalovirus (HCMV). Their IC50 values for HAdV ranged from 0.0039 µM for rotenone to 0.07 µM for tephrosin, with selective indices ranging from 164.1 for rotenone to 2,429.3 for deguelin. In addition, the inhibition of HCMV replication ranged from 50% to 92.1% at twice the IC50 concentrations obtained in the plaque assay for each compound against HAdV. Our results indicated that the mechanisms of action of rotenolone, deguelin, and tephrosin involve the late stages of the HAdV replication cycle. However, the antiviral mechanism of action of rotenone appears to involve the alteration of the microtubular polymerization, which prevents HAdV particles from reaching the nuclear membrane of the cell. These isoflavonoid-type compounds exert high antiviral activity against HAdV at nanomolar concentrations, and can be considered strong hit candidates for the development of a new class of broad-spectrum antiviral drugs.

COVID-19 Knowledge Extractor (COKE): A Curated Repository of Drug-Target Associations Extracted from the CORD-19 Corpus of Scientific Publications on COVID-19

The COVID-19 pandemic has catalyzed a widespread effort to identify drug candidates and biological targets of relevance to SARS-COV-2 infection, which resulted in large numbers of publications on this subject. We have built the COVID-19 Knowledge Extractor (COKE), a web application to extract, curate, and annotate essential drug-target relationships from the research literature on COVID-19. SciBiteAI ontological tagging of the COVID Open Research Data set (CORD-19), a repository of COVID-19 scientific publications, was employed to identify drug-target relationships. Entity identifiers were resolved through lookup routines using UniProt and DrugBank. A custom algorithm was used to identify co-occurrences of the target protein and drug terms, and confidence scores were calculated for each entity pair. COKE processing of the current CORD-19 database identified about 3000 drug-protein pairs, including 29 unique proteins and 500 investigational, experimental, and approved drugs. Some of these drugs are presently undergoing clinical trials for COVID-19. The COKE repository and web application can serve as a useful resource for drug repurposing against SARS-CoV-2. COKE is freely available at https://coke.mml.unc.edu/, and the code is available at https://github.com/DnlRKorn/CoKE.

The novel antiviral properties of brassicasterol against human adenovirus

Aim: To investigate whether brassicasterol has inhibitory effects against adenovirus (AdV). Materials & methods: The antiviral effects of brassicasterol against AdV 3 and 7 were tested in human airway epithelial cells. Brassicasterol cytotoxicity was assessed by WST-1 assay. AdV DNA was quantified by qPCR. Results: Brassicasterol inhibited AdV 3 and 7 infection of airway epithelial cells in a dose-dependent manner. Similarly, brassicasterol also inhibited AdV 3 and 7 production in infected cells. No apparent cytotoxicity of brassicasterol was detected. Further study showed that brassicasterol inhibited AdV DNA replication, but had no impact on viral entry of cells and viral genome import to nucleus. Conclusion: Brassicasterol exerts anti-AdV effects probably through the inhibition of viral DNA replication.

Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection

The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.

Antivirals that target the host IMPα/β1-virus interface

Although transport into the nucleus mediated by the importin (IMP) α/β1-heterodimer is central to viral infection, small molecule inhibitors of IMPα/β1-dependent nuclear import have only been described and shown to have antiviral activity in the last decade. Their robust antiviral activity is due to the strong reliance of many different viruses, including RNA viruses such as human immunodeficiency virus-1 (HIV-1), dengue (DENV), and Zika (ZIKV), on the IMPα/β1-virus interface. High-throughput compound screens have identified many agents that specifically target this interface. Of these, agents targeting IMPα/β1 directly include the FDA-approved macrocyclic lactone ivermectin, which has documented broad-spectrum activity against a whole range of viruses, including HIV-1, DENV1-4, ZIKV, West Nile virus (WNV), Venezuelan equine encephalitis virus, chikungunya, and most recently, SARS-CoV-2 (COVID-19). Ivermectin has thus far been tested in Phase III human clinical trials for DENV, while there are currently close to 80 trials in progress worldwide for SARS-CoV-2; preliminary results for randomised clinical trials (RCTs) as well as observational/retrospective studies are consistent with ivermectin affording clinical benefit. Agents that target the viral component of the IMPα/β1-virus interface include N-(4-hydroxyphenyl) retinamide (4-HPR), which specifically targets DENV/ZIKV/WNV non-structural protein 5 (NS5). 4-HPR has been shown to be a potent inhibitor of infection by DENV1-4, including in an antibody-dependent enhanced animal challenge model, as well as ZIKV, with Phase II clinical challenge trials planned. The results from rigorous RCTs will help determine the therapeutic potential of the IMPα/β1-virus interface as a target for antiviral development.

Heat Shock Protein 90 Chaperones E1A Early Protein of Adenovirus 5 and Is Essential for Replication of the Virus

Adenovirus infections tend to be mild, but they may pose a serious threat for young and immunocompromised individuals. The treatment is complicated because there are no approved safe and specific drugs for adenovirus infections. Here, we present evidence that 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG), an inhibitor of Hsp90 chaperone, decreases the rate of human adenovirus 5 (HAdV-5) replication in cell cultures by 95%. 17-AAG inhibited the transcription of early and late genes of HAdV-5, replication of viral DNA, and expression of viral proteins. 6 h after infection, Hsp90 inhibition results in a 6.3-fold reduction of the newly synthesized E1A protein level without a decrease in the E1A mRNA level. However, the Hsp90 inhibition does not increase the decay rate of the E1A protein that was constitutively expressed in the cell before exposure to the inhibitor. The co-immunoprecipitation proved that E1A protein interacted with Hsp90. Altogether, the presented results show, for the first time. that Hsp90 chaperones newly synthesized, but not mature, E1A protein. Because E1A serves as a transcriptional co-activator of adenovirus early genes, the anti-adenoviral activity of the Hsp90 inhibitor might be explained by the decreased E1A level.

COVID-19 Knowledge Extractor (COKE): A Tool and a Web Portal to Extract Drug - Target Protein Associations from the CORD-19 Corpus of Scientific Publications on COVID-19

Objective: The COVID-19 pandemic has catalyzed a widespread effort to identify drug candidates and biological targets of relevance to SARS-COV-2 infection, which resulted in large numbers of publications on this subject. We have built the COVID-19 Knowledge Extractor (COKE), a web application to extract, curate, and annotate essential drug-target relationships from the research literature on COVID-19 to assist drug repurposing efforts. Materials and Methods: SciBiteAI ontological tagging of the COVID Open Research Dataset (CORD-19), a repository of COVID-19 scientific publications, was employed to identify drug-target relationships. Entity identifiers were resolved through lookup routines using UniProt and DrugBank. A custom algorithm was used to identify co-occurrences of protein and drug terms, and confidence scores were calculated for each entity pair. Results: COKE processing of the current CORD-19 database identified about 3,000 drug-protein pairs, including 29 unique proteins and 500 investigational, experimental, and approved drugs. Some of these drugs are presently undergoing clinical trials for COVID-19. Discussion: The rapidly evolving situation concerning the COVID-19 pandemic has resulted in a dramatic growth of publications on this subject in a short period. These circumstances call for methods that can condense the literature into the key concepts and relationships necessary for insights into SARS-CoV-2 drug repurposing. Conclusion: The COKE repository and web application deliver key drug - target protein relationships to researchers studying SARS-CoV-2. COKE portal may provide comprehensive and critical information on studies concerning drug repurposing against COVID-19. COKE is freely available at https://coke.mml.unc.edu/ and the code is available at https://github.com/DnlRKorn/CoKE.

Recent Advances in Novel Antiviral Therapies against Human Adenovirus

Human adenovirus (HAdV) is a very common pathogen that typically causes minor disease in most patients. However, the virus can cause significant morbidity and mortality in certain populations, including young children, the elderly, and those with compromised immune systems. Currently, there are no approved therapeutics to treat HAdV infections, and the standard treatment relies on drugs approved to combat other viral infections. Such treatments often show inconsistent efficacy, and therefore, more effective antiviral therapies are necessary. In this review, we discuss recent developments in the search for new chemical and biological anti-HAdV therapeutics, including drugs that are currently undergoing preclinical/clinical testing, and small molecule screens for the identification of novel compounds that abrogate HAdV replication and disease.

Adenovirus infection and disease in recipients of hematopoietic cell transplantation

PURPOSE OF REVIEW

To provide an update on risk factors associated with adenovirus (ADV) infection in patients after hematopoietic cell transplant (HCT) and on options for ADV monitoring and treatment in the setting of HCT.

RECENT FINDINGS

Among patients undergoing HCT, ADV infection continues to be more common amongst those receiving a T-cell-depleted or graft other than from a matched-related donor. Among children undergoing HCT, reactivation in the gastrointestinal tract appears to be the most common source, and the virus is detectable by quantitative PCR in the stool before it is detectable in the blood. Thus, screening for the virus in the stool of these children may allow for preemptive therapy to reduce mortality. Brincidofovir, although still not approved by any regulatory agency, remains a potential agent for preemptive therapy and for salvage in cases not responding to cidofovir. Rapidly generated off-the-shelf virus-specific T cells may facilitate adoptive cell therapy in populations with a special need and previously not eligible for adoptive cell therapy, such as cord blood recipients.

SUMMARY

ADV infection continues to adversely affect survival in HCT recipients. Screening stool in children and preemptive therapy may reduce mortality. Brincidofovir and adoptive T-cell therapy remain potential options for treatment.

Identification of human adenovirus replication inhibitors from a library of small molecules targeting cellular epigenetic regulators

Human adenovirus (HAdV) can cause severe disease in certain at-risk populations such as newborns, young children, the elderly and individuals with a compromised immune system. Unfortunately, no FDA-approved antiviraldrug is currently available for the treatment of HAdV infections. Within the nucleus of infected cells, the HAdV genome associates with histones and forms a chromatin-like structure during early infection, and viral gene expression appears to be regulated by cellular epigenetic processes. Thus, one potential therapeutic strategy to combat HAdV disease may be to target the cellular proteins involved in modifying the viral nucleoprotein structure and facilitating HAdV gene expression and replication. We have screened a panel of small molecules that modulate the activity of epigenetic regulatory proteins for compounds affecting HAdV gene expression. Several of the compounds, specifically chaetocin, gemcitabine and lestaurtinib, reduced HAdV recovery by 100- to 1000-fold, while showing limited effects on cell health, suggesting that these compounds may indeed be promising as anti-HAdV therapeutics.

Management of Adenoviral Keratoconjunctivitis: Challenges and Solutions

Human adenovirus (HAdV) is the most common cause of infectious conjunctivitis, accounting for up to 75% of all conjunctivitis cases and affecting people of all ages and demographics. In addition to ocular complications, it can cause systemic infections in the form of gastroenteritis, respiratory disease, and dissemination in immunocompromised individuals. HAdV causes lytic infection of the mucoepithelial cells of the conjunctiva and cornea, as well as latent infection of lymphoid and adenoid cells. Epidemic keratoconjunctivitis (EKC) is the most severe ocular manifestation of HAdV infection, in which the presence of subepithelial infiltrates (SEIs) in the cornea is a hallmark feature of corneal involvement. SEIs have the tendency to recur and may lead to long-term visual disability. HAdV persistence and dissemination are linked to sporadic outbreaks of adenoviral keratoconjunctivitis. There is no FDA-approved antiviral for treating adenoviral keratoconjunctivitis, and as such, solutions should be proffered to handle the challenges associated with viral persistence and dissemination. Several treatment modalities have been investigated, both systemically and locally, to not only mitigate symptoms but reduce the course of the infection and prevent the risk of long-term complications. These options include systemic and topical antivirals, in-office povidone-iodine irrigation (PVI), immunoglobulin-based therapy, anti-inflammatory therapy, and immunotherapy. More recently, combination PVI/dexamethasone ophthalmic formulations have shown favorable outcomes and were well tolerated in clinical trials for the treatment of EKC. Possible, future treatment considerations include sialic acid analogs, cold atmospheric plasma, N-chlorotaurine, and benzalkonium chloride. Continued investigation and evaluation of treatment are warranted to reduce the economic burden and potential long-term visual debilitation in affected patients. This review will focus on how persistence and dissemination of HAdV pose a significant challenge to the management of adenoviral keratoconjunctivitis. Furthermore, current and future trends in prophylactic and therapeutic modalities for adenoviral keratoconjunctivitis will be discussed.

Repurposing approved drugs on the pathway to novel therapies

The time and cost of developing new drugs have led many groups to limit their search for therapeutics to compounds that have previously been approved for human use. Many "repurposed" drugs, such as derivatives of thalidomide, antibiotics, and antivirals have had clinical success in treatment areas well beyond their original approved use. These include applications in treating antibiotic-resistant organisms, viruses, cancers and to prevent burn scarring. The major theoretical justification for reusing approved drugs is that they have known modes of action and controllable side effects. Coadministering antibiotics with inhibitors of bacterial toxins or enzymes that mediate multidrug resistance can greatly enhance their activity. Drugs that control host cell pathways, including inflammation, tumor necrosis factor, interferons, and autophagy, can reduce the "cytokine storm" response to injury, control infection, and aid in cancer therapy. An active compound, even if previously approved for human use, will be a poor clinical candidate if it lacks specificity for the new target, has poor solubility or can cause serious side effects. Synergistic combinations can reduce the dosages of the individual components to lower reactivity. Preclinical analysis should take into account that severely ill patients with comorbidities will be more sensitive to side effects than healthy trial subjects. Once an active, approved drug has been identified, collaboration with medicinal chemists can aid in finding derivatives with better physicochemical properties, specificity, and efficacy, to provide novel therapies for cancers, emerging and rare diseases.

Structure-Activity Relationship Studies on Diversified Salicylamide Derivatives as Potent Inhibitors of Human Adenovirus Infection

The effective treatment of adenovirus (HAdV) infections in immunocompromised patients still poses great challenges. Herein, we reported our continued efforts to optimize a series of salicylamide derivatives as potent inhibitors of HAdV infection. Of these, nine compounds (11, 13, 14, 17, 20, 58, 60, 62, and 70) showed significantly improved anti-HAdV activities with nanomolar to submicromolar IC₅₀ values and high selectivity indexes (SI > 100), indicating better safety windows, compared to those of the lead compound niclosamide. Our mechanistic assays suggest that compounds 13, 62, and 70 exert their activities in the HAdV entry pathway, while compounds 14 and 60 likely target the HAdV DNA replication, and 11, 17, 20, and 58 inhibit later steps after DNA replication. Given the broad anti-viral activity profile of niclosamide, these derivatives may also offer therapeutic potential for other viral infections.

Development of a novel screening platform for the identification of small molecule inhibitors of human adenovirus

Human adenovirus (HAdV) can cause severe disease and death in both immunocompromised and immunocompetent patients. The current standards of treatment are often ineffective, and no approved antiviral therapy against HAdV exists. We report here the design and validation of a fluorescence-based high-content screening platform for the identification of novel anti-HAdV compounds. The screen was conducted using a wildtype-like virus containing the red fluorescent protein (RFP) gene under the regulation of the HAdV major late promoter. Thus, RFP expression allows monitoring of viral late gene expression (a surrogate marker for virus replication), and compounds affecting virus growth can be easily discovered by quantifying RFP intensity. We used our platform to screen ~1200 FDA-approved small molecules, and identified several cardiotonic steroids, corticosteroids and chemotherapeutic agents as anti-HAdV compounds. Our screening platform provides the stringency necessary to detect compounds with varying degrees of antiviral activity, and facilitates drug discovery/repurposing to combat HAdV infections.

Drug development against human adenoviruses and its advancement by Syrian hamster models

The symptoms of human adenovirus infections are generally mild and self-limiting. However, these infections have been gaining importance in recent years because of a growing number of immunocompromised patients. Solid organ and hematopoietic stem cell transplant patients are subjected to severe immunosuppressive regimes and cannot efficaciously eliminate virus infections. In these patients, adenovirus infections can develop into deadly multi-organ disseminated disease. Presently, in the absence of approved therapies, physicians rely on drugs developed for other purposes to treat adenovirus infections. As there is a need for anti-adenoviral therapies, researchers have been developing new agents and repurposing existing ones to treat adenovirus infections. There are several small molecule drugs that are being tested for their efficacy against human adenoviruses; some of these have reached clinical trials, while others are still in the preclinical phase. Besides these compounds, research on immunotherapy against adenoviral infection has made significant progress, promising another modality for treatment. The availability of an animal model confirmed the activity of some drugs already in clinical use while proving that others are inactive. This led to the identification of several lead compounds that await further development. In the present article, we review the current status of anti-adenoviral therapies and their advancement by in vivo studies in the Syrian hamster model.

Viral Appropriation: Laying Claim to Host Nuclear Transport Machinery

Protein nuclear transport is an integral process to many cellular pathways and often plays a critical role during viral infection. To overcome the barrier presented by the nuclear membrane and gain access to the nucleus, virally encoded proteins have evolved ways to appropriate components of the nuclear transport machinery. By binding karyopherins, or the nuclear pore complex, viral proteins influence their own transport as well as the transport of key cellular regulatory proteins. This review covers how viral proteins can interact with different components of the nuclear import machinery and how this influences viral replicative cycles. We also highlight the effects that viral perturbation of nuclear transport has on the infected host and how we can exploit viruses as tools to study novel mechanisms of protein nuclear import. Finally, we discuss the possibility that drugs targeting these transport pathways could be repurposed for treating viral infections.

Repositioning salicylanilide anthelmintic drugs to treat adenovirus infections

The repositioning of drugs already approved by regulatory agencies for other indications is an emerging alternative for the development of new antimicrobial therapies. The repositioning process involves lower risks and costs than the de novo development of novel antimicrobial drugs. Currently, infections by adenovirus show a steady increment with a high clinical impact in immunosuppressed and immunocompetent patients. The lack of a safe and efficacious drug to treat these infections supports the search for new antiviral drugs. Here we evaluated the anti-adenovirus activity of niclosanide, oxyclozanide, and rafoxanide, three salicylanilide anthelmintic drugs. Also, we carried out the cytotoxicity evaluation and partial characterization of the mechanism of action of these drugs. The salicylanilide anthelmintic drugs showed significant anti-adenovirus activity at low micromolar concentrations with little cytotoxicity. Moreover, our mechanistic assays suggest differences in the way the drugs exert anti-adenovirus activity. Niclosamide and rafoxanide target transport of the HAdV particle from the endosome to the nuclear envelope, whilst oxyclozanide specifically targets adenovirus immediately early gene E1A transcription. Data suggests that the studied salicylanilide anthelmintic drugs could be suitable for further clinical evaluation for the development of new antiviral drugs to treat infections by adenovirus in immunosuppressed patients and in immunocompetent individuals with community-acquired pneumonia.