Antiviral activity of arbidol, a broad-spectrum drug for use against respiratory viruses, varies according to test conditions

Drug resistance and possible therapeutic options against influenza A virus infection over past years

Influenza A virus infection, commonly known as the flu, has persisted in the community for centuries. Although we have yearly vaccinations to prevent seasonal flu, there remains a dire need for antiviral drugs to treat active infections. The constantly evolving genome of the influenza A virus limits the number of effective antiviral therapeutic options. Over time, antiviral drugs become inefficient due to the development of resistance, as seen with adamantanes, which are now largely ineffective against most circulating strains of the virus. Neuraminidase inhibitors have long been the drug of choice, but due to selection pressure, strains are becoming resistant to this class of drugs. Baloxavir marboxil, a drug with a novel mode of action, can be used against strains resistant to other classes of drugs but is still not available in many countries. Deep research into nanoparticles has shown they are effective as antiviral drugs, opening a new avenue of research to use them as antiviral agents with novel modes of action. As this deadly virus, which has killed millions of people in the past, continues to develop resistance, there is an urgent need for new therapeutic agents with novel modes of action to halt active infections in patients. This review article covers the available therapeutic antiviral drug options with different modes of action, their effectiveness, and resistance to various strains of influenza A virus.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Antiviral options and therapeutics against influenza: history, latest developments and future prospects

Drugs and chemotherapeutics have helped to manage devastating impacts of infectious diseases since the concept of 'magic bullet'. The World Health Organization estimates about 650,000 deaths due to respiratory diseases linked to seasonal influenza each year. Pandemic influenza, on the other hand, is the most feared health disaster and probably would have greater and immediate impact on humanity than climate change. While countermeasures, biosecurity and vaccination remain the most effective preventive strategies against this highly infectious and communicable disease, antivirals are nonetheless essential to mitigate clinical manifestations following infection and to reduce devastating complications and mortality. Continuous emergence of the novel strains of rapidly evolving influenza viruses, some of which are intractable, require new approaches towards influenza chemotherapeutics including optimization of existing anti-infectives and search for novel therapies. Effective management of influenza infections depend on the safety and efficacy of selected anti-infective in-vitro studies and their clinical applications. The outcomes of therapies are also dependent on understanding diversity in patient groups, co-morbidities, co-infections and combination therapies. In this extensive review, we have discussed the challenges of influenza epidemics and pandemics and discoursed the options for anti-viral chemotherapies for effective management of influenza virus infections.

Arbidol increases the survival rate by mitigating inflammation in suckling mice infected with human coronavirus OC43 virus

Human coronavirus OC43 (HCoV-OC43) often causes common cold and is able to neuroinvasive, but it can also induce lower respiratory tract infections (LRTI) especially in children and the elderly adults with underlying diseases. HCoV-OC43 infections currently have no approved antiviral treatment. Arbidol (ARB) is a broad-spectrum antiviral and is an antiviral medication for the treatment of influenza used in Russia and China. Due to its multiple mechanisms of action, such as inhibition of viral fusion and entry, immunomodulation, and modulation of host cell signaling pathways, ARB has the potential to be an effective treatment option for viral infections. Therefore, the study aims to investigate the activities of ARB against HCoV-OC43 infections. Suckling mice were infected with HCoV-OC43 and treated with ARB (50, 25 and 12.5 mg/kg/d) by gavage once daily for 4 days. the survival rates and body weight were recorded, the viral titer was measured by real-time quantitative polymerase chain reaction, cytokine levels were measured by Bio-Plex assays. Histopathological changes of the lungs and brain were analyzed. Our results show ARB increased the survival rate, reduced viral copy numbers in the lung, mitigated pro-inflammatory cytokine production, and improved brain and lung histopathology significantly without any significant toxicity or side effects in vivo. Our results suggest ARB could be a promising approach for the prevention and treatment of HCoV-OC43 while further studies are needed to address these possibilities and the underlying mechanism.

Arbidol: The current demand, strategies, and antiviral mechanisms

BACKGROUND

High morbidity and mortality of influenza virus infection have made it become one of the most lethal diseases threatening public health; the lack of drugs with strong antiviral activity against virus strains exacerbates the problem.

METHODS

Two independent researchers searched relevant studies using Embase, PubMed, Web of Science, Google Scholar, and MEDLINE databases from its inception to December 2022.

RESULTS

Based on the different antiviral mechanisms, current antiviral strategies can be mainly classified into virus-targeting approaches such as neuraminidase inhibitors, matrix protein 2 ion channel inhibitors, polymerase acidic protein inhibitors and other host-targeting antivirals. However, highly viral gene mutation has underscored the necessity of novel antiviral drug development. Arbidol (ARB) is a Russian-made indole-derivative small molecule licensed in Russia and China for the prevention and treatment of influenza and other respiratory viral infections. ARB also has inhibitory effects on many other viruses such as severe acute respiratory syndrome coronavirus 2, Coxsackie virus, respiratory syncytial virus, Hantaan virus, herpes simplex virus, and hepatitis B and C viruses. ARB is a promising drug which can not only exert activity against virus at different steps of virus replication cycle, but also directly target on hosts before infection to prevent virus invasion.

CONCLUSION

ARB is a broad-spectrum antiviral drug that inhibits several viruses in vivo and in vitro, with high safety profile and low resistance; the antiviral mechanisms of ARB deserve to be further explored and more high-quality clinical studies are required to establish the efficacy and safety of ARB.

Development of an HiBiT-tagged reporter H3N2 influenza A virus and its utility as an antiviral screening platform

The balance of the segmented genome derived from naturally occurring influenza A viruses (IAVs) is delicate and vulnerable to foreign insertions, thus most reporter IAVs up to date are generated using the backbone of the laboratory-adapted strains. In this study, we constructed a reporter influenza A/H3N2 virus (A/NY-HiBiT) which was derived from a clinical isolate, by placing a minimized HiBiT tag to the N-terminus of the viral nuclear-export protein (NEP). Here, we show that this 11-amino acid HiBiT tag did not adversely impact the viral genome balance, and the recombinant A/NY-HiBiT virus maintains its relative stability. Moreover, the replication profile of the HiBiT-tagged virus can be measured by a simple Nano-Glo assay, providing a robust high-throughput screening (THS) platform. We used this platform to evaluate a collection of the pre-purified fractions which were derived from rare Chinese medicinal materials, and we identified three fractions, including wild Trametes robiniophila (50% methanol fraction), Ganoderma (water fraction), and wild Phellinus igniarius (ethyl acetate fraction), as potent anti-IAV actives. Our results demonstrate that this IAV reporter can be used as a powerful HTS platform for antiviral development.

Hemagglutinin Stability Determines Influenza A Virus Susceptibility to a Broad-Spectrum Fusion Inhibitor Arbidol

Understanding mechanisms of resistance to antiviral inhibitors can reveal nuanced features of targeted viral mechanisms and, in turn, lead to improved strategies for inhibitor design. Arbidol is a broad-spectrum antiviral that binds to and prevents the fusion-associated conformational changes in the trimeric influenza A virus (IAV) hemagglutinin (HA). The rate-limiting step during the HA-mediated membrane fusion is the release of the hydrophobic fusion peptides from a conserved pocket on HA. Here, we investigated how destabilizing or stabilizing mutations in or near the fusion peptide affect viral sensitivity to Arbidol. The degree of sensitivity was proportional to the extent of fusion-peptide stability on the prefusion HA: stabilized mutants were more sensitive, and destabilized ones were resistant to Arbidol. Single-virion membrane fusion experiments for representative wild-type (WT) and mutant viruses demonstrated that resistance is a direct consequence of fusion-peptide destabilization not requiring reduced Arbidol binding to HA. Our results support the model whereby the probability of individual HAs extending to engage the target membrane is determined by the composite of two critical forces: a "tug" on the fusion peptide by HA rearrangements near the Arbidol binding site and the key interactions stabilizing the fusion peptide in the prefusion pocket. Arbidol increases and destabilizing mutations decrease the free-energy cost for fusion-peptide release, accounting for the observed resistance. Our findings have broad implications for fusion inhibitor design, viral mechanisms of resistance, and our basic understanding of HA-mediated membrane fusion.

Understanding Immune Responses to Viruses-Do Underlying Th1/Th2 Cell Biases Predict Outcome?

Emerging and re-emerging viral diseases have increased in number and geographical extent during the last decades. Examples include the current COVID-19 pandemic and the recent epidemics of the Chikungunya, Ebola, and Zika viruses. Immune responses to viruses have been well-characterised within the innate and adaptive immunity pathways with the outcome following viral infection predominantly attributed to properties of the virus and circumstances of the infection. Perhaps the belief that the immune system is often considered as a reactive component of host defence, springing into action when a threat is detected, has contributed to a poorer understanding of the inherent differences in an individual's immune system in the absence of any pathology. In this review, we focus on how these host factors (age, ethnicity, underlying pathologies) may skew the T helper cell response, thereby influencing the outcome following viral infection but also whether we can use these inherent biases to predict patients at risk of a deviant response and apply strategies to avoid or overcome them.

Mosquito-Borne Flaviviruses and Current Therapeutic Advances

Mosquito-borne flavivirus infections affect approximately 400 million people worldwide each year and are global threats to public health. The common diseases caused by such flaviviruses include West Nile, yellow fever, dengue, Zika infection and Japanese encephalitis, which may result in severe symptoms and disorders of multiple organs or even fatal outcomes. Till now, no specific antiviral agents are commercially available for the treatment of the diseases. Numerous strategies have been adopted to develop novel and promising inhibitors against mosquito-borne flaviviruses, including drugs targeting the critical viral components or essential host factors during infection. Research advances in antiflaviviral therapy might optimize and widen the treatment options for flavivirus infection. This review summarizes the current developmental progresses and involved molecular mechanisms of antiviral agents against mosquito-borne flaviviruses.

Modeling the Structure-Activity Relationship of Arbidol Derivatives and Other SARS-CoV-2 Fusion Inhibitors Targeting the S2 Segment of the Spike Protein

Umifenovir (Arbidol) has been reported to exhibit some degree of efficacy in multiple clinical trials for the treatment of COVID-19 as a monotherapy. It has also demonstrated synergistic inhibition of SARS-CoV-2 with other direct-acting antivirals such as Remdesivir. A computational approach was used to identify the most favorable binding site to the SARS-CoV-2 Spike S2 segment and to perform virtual screening. Compounds selected from modeling were evaluated in a live SARS-CoV-2 infection assay. An Arbidol (ARB) derivative with substitutions at both the C-4 and C-6 positions was found to exhibit a modest improvement in activity and solubility properties in comparison to ARB. However, all of the derivatives were found to only be partial inhibitors, rather than full inhibitors in a virus-induced cytopathic effect-based assay. The binding mode is also corroborated by parallel modeling of a series of oleanolic acid trisaccharide saponin fusion inhibitors shown to bind to the S2 segment. Recently determined experimental structures of the Spike protein allowed atomic resolution modeling of fusion inhibitor binding as a function of pH, and the implications for the molecular mechanism of direct-acting fusion inhibitors targeting the S2 segment are discussed.

Efficacy and safety of arbidol (umifenovir) in patients with COVID-19: A systematic review and meta-analysis

OBJECTIVE

To provide the latest evidence for the efficacy and safety of arbidol (umifenovir) in COVID-19 treatment.

METHODS

A literature systematic search was carried out in PubMed, Cochrane Library, Embase, and medRxiv up to May 2021. The Cochrane risk of bias tool and Newcastle-Ottawa scale were used to assess the quality of included studies. Meta-analysis was performed using RevMan 5.3.

RESULTS

Sixteen studies were met the inclusion criteria. No significant difference was observed between arbidol and non-antiviral treatment groups neither for primary outcomes, including the negative rate of PCR (NR-PCR) on Day 7 (risk ratio [RR]: 0.94; 95% confidence interval (CI): 0.78-1.14) and Day 14 (RR: 1.10; 95% CI: 0.96-1.25), and PCR negative conversion time (PCR-NCT; mean difference [MD]: 0.74; 95% CI: -0.87 to 2.34), nor secondary outcomes (p > .05). However, arbidol was associated with higher adverse events (RR: 2.24; 95% CI: 1.06-4.73). Compared with lopinavir/ritonavir, arbidol showed better efficacy for primary outcomes (p < .05). Adding arbidol to lopinavir/ritonavir also led to better efficacy in terms of NR-PCR on Day 7 and PCR-NCT (p < .05). There was no significant difference between arbidol and chloroquine in primary outcomes (p > .05). No remarkable therapeutic effect was observed between arbidol and other agents (p > .05).

CONCLUSION

The present meta-analysis showed no significant benefit of using arbidol compared with non-antiviral treatment or other therapeutic agents against COVID-19 disease. High-quality studies are needed to establish the efficacy and safety of arbidol for COVID-19.

Indole alkaloids inhibit zika and chikungunya virus infection in different cell lines

BACKGROUND

In recent years, an increase in the occurrence of illnesses caused by two clinically- important arboviruses has been reported: Zika virus (ZIKV) and Chikungunya virus (CHIKV). There is no licensed antiviral treatment for either of the two abovementioned viruses. Bearing in mind that the antiviral effect of indole alkaloids has been reported for other arboviral models, the present study proposed to evaluate the antiviral in vitro and in silico effects of four indole alkaloids on infections by these two viruses in different cell lines.

METHODS

The antiviral effects of voacangine (VOAC), voacangine-7-hydroxyindolenine (VOAC-OH), rupicoline and 3-oxo voacangine (OXO-VOAC) were evaluated in Vero, U937 and A549 cells using different experimental strategies (Pre, Trans, Post and combined treatment). Viral infection was quantified by different methodologies, including infectious viral particles by plating, viral genome by RT-qPCR, and viral protein by cell ELISA. Moreover, molecular docking was used to evaluate the possible interactions between structural and nonstructural viral proteins and the compounds. The results obtained from the antiviral strategies for each experimental condition were compared in all cases with the untreated controls. Statistically significant differences were identified using a parametric Student's t-test. In all cases, p values below 0.05 (p < 0.05) were considered statistically significant.

RESULTS

In the pre-treatment strategy in Vero cells, VOAC and VOAC-OH inhibited both viral models and OXO-VOAC inhibited only ZIKV; in U937 cells infected with CHIKV/Col, only VOAC-OH inhibited infection, but none of the compounds had activity in A549 cells; in U937 cells and A549 cells infected with ZIKV/Col, the three compounds that were effective in Vero cells also had antiviral activity. In the trans-treatment strategy, only VOAC-OH was virucidal against ZIKV/Col. In the post-treatment strategy, only rupicoline was effective in the CHIKV/Col model in Vero and A549 cells, whereas VOAC and VOAC-OH inhibited ZIKV infection in all three cell lines. In the combined strategy, VOAC, VOAC-OH and rupicoline inhibited CHIKV/Col and ZIKV/Col, but only rupicoline improved the antiviral effect of ZIKV/Col-infected cultures with respect to the individual strategies. Molecular docking showed that all the compounds had favorable binding energies with the structural proteins E2 and NSP2 (CHIKV) and E and NS5 (ZIKV).

CONCLUSIONS

The present study demonstrates that indole alkaloids are promising antiviral drugs in the process of ZIKV and CHIKV infection; however, the mechanisms of action evaluated in this study would indicate that the effect is different in each viral model and, in turn, dependent on the cell line.

New Approaches and Repurposed Antiviral Drugs for the Treatment of the SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that causes coronavirus disease 2019 (COVID-19). The outbreak of this coronavirus was first identified in Wuhan (Hubei, China) in December 2019, and it was declared as pandemic by the World Health Organization (WHO) in March 2020. Today, several vaccines against SARS-CoV-2 have been approved, and some neutralizing monoclonal antibodies are being tested as therapeutic approaches for COVID-19 but, one of the key questions is whether both vaccines and monoclonal antibodies could be effective against infections by new SARS-CoV-2 variants. Nevertheless, there are currently more than 1000 ongoing clinical trials focusing on the use and effectiveness of antiviral drugs as a possible therapeutic treatment. Among the classes of antiviral drugs are included 3CL protein inhibitors, RNA synthesis inhibitors and other small molecule drugs which target the ability of SARS-COV-2 to interact with host cells. Considering the need to find specific treatment to prevent the emergent outbreak, the aim of this review is to explain how some repurposed antiviral drugs, indicated for the treatment of other viral infections, could be potential candidates for the treatment of COVID-19.

Antiviral treatment selection for SARS-CoV-2 pneumonia

INTRODUCTION

Therapy of coronavirus disease 2019 (COVID-19) involves evolving algorithms that include drugs aimed at reducing disease progression by counteracting two different, but intertwined processes: (i) the damage caused by the virus (with antivirals); (ii) the damage caused by a dysregulated host response (with immunomodulatory agents).

AREAS COVERED

Herein, we discuss the available evidence on the efficacy and safety of antiviral agents employed over the past months for the treatment of COVID-19, and the reasons to be considered for antiviral selection.

EXPERT OPINION

The available evidence from randomized controlled trials (RCT) currently discourages the use of lopinavir/ritonavir, hydroxychloroquine, and interferons, which did not show improved efficacy compared to standard care or placebo. Regarding remdesivir, the current body of evidence may conditionally support its use in COVID-19 patients requiring oxygen supplementation but still not requiring invasive mechanical ventilation. Finally, neutralizing monoclonal antibodies have been proven efficacious in reducing the risk of severe disease development if administered early in the course of the disease to patients at risk of progression. The results of the ongoing RCT will certainly be crucial to further improve our understanding of the optimal place in therapy of antiviral agents for COVID-19.

Therapeutic Development in COVID-19

Since the outbreak of coronavirus disease 2019 (COVID-19) caused by the SARS-CoV-2, the disease has spread rapidly worldwide and developed into a global pandemic, causing a significant impact on the global health system and economic development. Scientists have been racing to find effective drugs and vaccines for the treatment and prevention of COVID-19. However, due to the diversity of clinical manifestations caused by COVID-19, no standard antiviral regimen beyond supportive therapy has been established. Ongoing clinical trials are underway to evaluate the efficacy of drugs that primarily act on the viral replication cycle or enhanced immunity of patients. This chapter will summarize the currently used antiviral and adjuvant therapies in clinical practice and provide a theoretical basis for the future treatment of COVID-19.

Coronavirus disease 2019 (COVID-19) in a Chinese renal transplant recipient: a case report

Since December 2019, a novel coronavirus that caused viral pneumonia broke out and became global pandemic. Coronavirus disease 2019 (COVID-19) is caused by the SARS-CoV-2 virus. Reports on the clinical manifestations in solid organ transplant (SOT) recipients are rare. We report the clinical features and treatment of a Chinese renal transplant recipient with COVID-19. A 46-year-old Chinese woman, who had a renal transplant in 2006 due to chronic glomerulonephritis, was admitted to Renmin Hospital of Wuhan University for fever, cough, and expectoration for more than 10 days and diarrhea for 3 days. At admission, her body temperature was 38.2 °C and pulse oxygen saturation was 96% under oxygen inhalation. There were decreased breath sounds bilaterally. Laboratory data revealed normal leucocyte count, a normal percentage of neutrophils, a normal percentage of lymphocytes, decreased lymphocyte count, elevated procalcitonin and C-reactive protein (CRP), and increased levels of urea, creatinine, and estimated glomerular filtration rate. COVID-19 was confirmed by nasopharyngeal swab and sputum which were positive for SARS-CoV-2 by real-time reverse transcription PCR (RT-PCR). Chest CT revealed multiple patchy and flake ground-glass shadows in bilateral lung fields, and strip shadows in bilateral lower lobes. Treatment included antiviral (umifenovir, hydroxychloroquine), antibacterial (moxifloxacin), and other support therapies. Her symptoms, laboratory data, and chest CT showed trends of gradual improvement, while nasopharyngeal swabs were always positive for SARS-CoV-2. She was finally discharged from hospital on her 70th day of hospitalization when 2 consecutive nasopharyngeal swabs were negative for SARS-CoV-2. This is a rare report on COVID-19 in a renal transplant recipient, which can help enhance the understanding and treatment of COVID-19 in renal transplant recipients.

Improving the Solubilization and Bioavailability of Arbidol Hydrochloride by the Preparation of Binary and Ternary β-Cyclodextrin Complexes with Poloxamer 188

In the current study, the effect of poloxamer 188 on the complexation efficiency and dissolution of arbidol hydrochloride (ADL), a broad-spectrum antiviral agent, with β-cyclodextrin (β-CD) was investigated. Phase solubility studies confirmed a stoichiometry of a 1:1 ratio for both ADL:β-CD and ADL/β-CD with a 1% poloxamer 188 system with an AL type of phase solubility curve. The stability constants (K1:1) calculated from the AL type diagram were 550 M-1 and 2134 M-1 for AD:β-CD and ADL/β-CD with 1% poloxamer 188, respectively. The binary ADL/β-CD and ternary ADL/β-CD with 1% poloxamer 188 complexes were prepared by kneading and a solvent evaporation method and were characterized by aqueous solubility, FTIR, PXRD, DSC and SEM in vitro studies. The solubility (13.1 fold) and release of ADL were markedly improved in kneaded ternary ADL/β-CD with 1% poloxamer 188 (KDB). The binding affinity of ADL and β-CD was confirmed by ¹H NMR and 2D ROSEY studies. The ternary complex (KDB) was further subjected for in vivo pharmacokinetic studies in rats and a significant improvement in the bioavailability (2.17 fold) was observed in comparison with pure ADL. Therefore, it can be concluded that the solubilization and bioavailability of ADL can be remarkably increased by ADL/β-CD complexation in the presence of a third component, poloxamer 188.

Antivirals Targeting the Surface Glycoproteins of Influenza Virus: Mechanisms of Action and Resistance

Hemagglutinin and neuraminidase, which constitute the glycoprotein spikes expressed on the surface of influenza A and B viruses, are the most exposed parts of the virus and play critical roles in the viral lifecycle. As such, they make prominent targets for the immune response and antiviral drugs. Neuraminidase inhibitors, particularly oseltamivir, constitute the most commonly used antivirals against influenza viruses, and they have proved their clinical utility against seasonal and emerging influenza viruses. However, the emergence of resistant strains remains a constant threat and consideration. Antivirals targeting the hemagglutinin protein are relatively new and have yet to gain global use but are proving to be effective additions to the antiviral repertoire, with a relatively high threshold for the emergence of resistance. Here we review antiviral drugs, both approved for clinical use and under investigation, that target the influenza virus hemagglutinin and neuraminidase proteins, focusing on their mechanisms of action and the emergence of resistance to them.

Comparison the Effect of Arbidol Plus Hydroxychloroquine vs Hydroxychloroquine Alone in Treatment of COVID-19 Disease: A Randomized Clinical Trial

Background and Aim:

The main challenging issue about coronavirus disease 2019 (COVID-19) is the production of safe and stable vaccines, which is a very long process. Due to the emergency situation, regular and extensive screening of available and traditional drugs, which are commonly used for the treatment of similar viral diseases, can be a reasonable option. The present study aimed to compare the administration of hydroxychloroquine (HCQ) plus arbidol to the use of HCQ alone in the treatment of COVID-19 infection.

Methods and Materials:

This single-blind randomized controlled trial was carried out on a total of 100 patients with COVID-19 referring to the infection ward of Imam Reza Hospital in Mashhad, Iran, in 2020. The patients were randomly assigned to two HCQ alone and HCQ plus arbidol groups.

Results:

According to the obtained results, hematological parameters, including white blood cell count, hemoglobin level, lymphocyte count, and platelet count, improved in patients with COVID-19 after the treatment with both HCQ plus arbidol and HCQ alone (P<0.005). The mean values of the reduction time of C-reactive protein (CRP) were 4.48±1.24 and 8.22±2.08 days in the arbidol and HCQ alone groups, respectively, indicating that CRP decreased faster in the arbidol group than that reported for the HCQ alone group (Z=0.-7.85; P<0.000). The mean scores of hospital stay were reported as 5.89±2.04 and 9.35±3.72 days in the arbidol and HCQ alone groups, respectively (Z=-4.31; P<0.005). All the patients in the arbidol group survived, while 6% of the subjects in the HCQ alone group died. In addition, the drug regimen was not changed for any patient, and no subject was transferred to the intensive care unit in the arbidol group.

Conclusion:

In summary, the administration of both arbidol and HCQ leads to the improvement of the hematological parameters. The present study introduced arbidol as an effective treatment for moderate to severe patients with COVID-19, which not only reduced the time of CRP normalization level but also decreased the hospitalization duration and mortality compared to those reported for HCQ.

[Umifenovir and coronavirus infections: a review of research results and clinical practice]

Coronaviruses are known to cause acute respiratory infections. Antiviral therapy, including for COVID-19, is based on clinical practice, experimental data and trial results. The purpose of this review is to: provide and systematize actual preclinical data, clinical trials results and clinical practice for antiviral agent umifenovir (Arbidol). Databases Scopus, Web of Science, RSCI and medRxiv were used for publication searching from 2004. A meta-analysis of clinical trials results was performed. Umifenovir is antiviral agent, it belongs to fusion inhibitors, interacts with SARS-CoV-2 spike protein. Umifenovir the impede the trimerization of spike glycoprotein and inhibit host cell adhesion, at the level of the coronaviruses S-protein of interaction with ACE2 receptor. Preclinical studies in vitro and on animals show umifenovir activity against a number of coronaviruses, including SARS-CoV, MERS-CoV, SARS-CoV-2, and others. Umifenovir, in combination with other antiviral drugs, symptomatic or traditional medicine, was used in China to treat patients with COVID-19, resulting in reduced mortality, virus elimination, the frequency of more severe course and complications in middle severity. However, antiviral therapy for the treatment of severe patients, with ARDS, did not lead to improved outcomes. In comparative clinical studies, umifenovir showed similar effectiveness with other antiviral drugs, and lower frequency of adverse reactions. Therapy with umifenovir, led to an increase percentage of patients with negative results of PCR tests on days 714 (I2=69.8%, RR 0.48, 95% CI 0.190.76; p=0.001). The efficacy and safety of antivirals against SARS-CoV-2 still requires clinical investigation. Moderate forms of COVID-19 could be effectively treated by antivirals, but severe forms of COVID-19, characterized by pulmonary immunopathology, require different approaches to treatment.

Repurposing Approved Drugs for Guiding COVID-19 Prophylaxis: A Systematic Review

The SARS-CoV-2 outbreak originally appeared in China in December 2019 and became a global pandemic in March 2020. This infectious disease has directly affected public health and the world economy. Several palliative therapeutic treatments and prophylaxis strategies have been used to control the progress of this viral infection, including pre-(PrEP) and post-exposure prophylaxis. On the other hand, research groups around the world are still studying novel drug prophylaxis and treatment using repurposing approaches, as well as vaccination options, which are in different pre-clinical and clinical testing phases. This systematic review evaluated 1,228 articles from the PubMed and Scopus indexing databases, following the Kitchenham bibliographic searching protocol, with the aim to list drug candidates, potentially approved to be used as new options for SARS-CoV-2 prophylaxis clinical trials and medical protocols. In searching protocol, we used the following keywords: "Covid-19 or SARS-CoV-2" or "Coronavirus or 2019 nCoV," "prophylaxis," "prophylactic," "pre-exposure," "COVID-19 or SARS-CoV-2 Chemoprophylaxis," "repurposed," "strategies," "clinical," "trials," "anti-SARS-CoV-2," "anti-covid-19," "Antiviral," "Therapy prevention in vitro," in cells "and" human testing. After all protocol steps, we selected 60 articles that included: 15 studies with clinical data, 22 studies that used in vitro experiments, seven studies using animal models, and 18 studies performed with in silico experiments. Additionally, we included more 22 compounds between FDA approved drugs and drug-like like molecules, which were tested in large-scale screenings, as well as those repurposed approved drugs with new mechanism of actions. The drugs selected in this review can assist clinical studies and medical guidelines on the rational repurposing of known antiviral drugs for COVID-19 prophylaxis.

Derivatization and combination therapy of current COVID-19 therapeutic agents: a review of mechanistic pathways, adverse effects, and binding sites

Current treatment of patients with coronavirus 2019 (COVID-19) involves repurposed drugs that inhibit viral infection by either binding to their respective targets or via modulating cellular signal transduction. However, there is still a great deal of efficacy enhancement through combination therapy and derivatization. Combination therapy should involve agents with significant activity and different mechanisms of action. The structural map of the interaction between a drug and its target protein will help guide drug discovery for devising safe and effective ways to treat COVID-19. Herein, we report numerous synthetic designs based on enhanced affinity to the viral carbohydrate-rich protein spikes and protein-binding sites of COVID-19.

Pharmacokinetics/Pharmacodynamics of Antiviral Agents Used to Treat SARS-CoV-2 and Their Potential Interaction with Drugs and Other Supportive Measures: A Comprehensive Review by the PK/PD of Anti-Infectives Study Group of the European Society of Antimicrobial Agents

There is an urgent need to identify optimal antiviral therapies for COVID-19 caused by SARS-CoV-2. We have conducted a rapid and comprehensive review of relevant pharmacological evidence, focusing on (1) the pharmacokinetics (PK) of potential antiviral therapies; (2) coronavirus-specific pharmacodynamics (PD); (3) PK and PD interactions between proposed combination therapies; (4) pharmacology of major supportive therapies; and (5) anticipated drug-drug interactions (DDIs). We found promising in vitro evidence for remdesivir, (hydroxy)chloroquine and favipiravir against SARS-CoV-2; potential clinical benefit in SARS-CoV-2 with remdesivir, the combination of lopinavir/ritonavir (LPV/r) plus ribavirin; and strong evidence for LPV/r plus ribavirin against Middle East Respiratory Syndrome (MERS) for post-exposure prophylaxis in healthcare workers. Despite these emerging data, robust controlled clinical trials assessing patient-centred outcomes remain imperative and clinical data have already reduced expectations with regard to some drugs. Any therapy should be used with caution in the light of potential drug interactions and the uncertainty of optimal doses for treating mild versus serious infections.

Current Approaches to COVID-19: Therapy and Prevention

The coronavirus disease-2019 (COVID-19) pandemic has affected millions of people worldwide. As our understanding of the disease is evolving, our approach to the patient management is also changing swiftly. Available new evidence is helping us take radical decisions in COVID-19 management. We searched for inclusion of the published literature on treatment of COVID-19 from around the globe. All relevant evidences available till the time of submission of this article were briefly discussed. Once advised as blanket therapy for all patients, recent reports of hydroxychloroquine with or without azithromycin indicated no potential benefit and use of such combination may increase the risk of arrhythmias. Clinical evidence with newer antivirals such as remdesivir and favipiravir is promising that can hasten the patient recovery and reduce the mortality. With steroids, evidence is much clear in that it should be used in low dose and for short period not extending beyond 7 days in moderate to severe hospitalized patients. Low-molecular-weight heparin should be initiated in all hospitalized COVID-19 patients and dose should be based on the coagulation profile and risk of thromboembolism. Immunomodulatory drugs such tocilizumab may be considered for severe and critically ill patients to improve the outcomes. Though ulinastatin can be a potential alternative immunomodulator, there is lack of clinical evidence on its usage in COVID-19. Convalescent plasma therapy can be potentially lifesaving in critically ill patients. However, there is need to generate further evidence with various such therapies. Though availability of a potent vaccine is awaited, current treatment of COVID-19 is based on available therapies, which is guided by the evidence. In this review, we discuss the potential treatments available around the globe with current evidence on each of such treatments. How to cite this article: Dixit SB, Zirpe KG, Kulkarni AP, Chaudhry D, Govil D, Mehta Y, et al. Current Approaches to COVID-19: Therapy and Prevention. Indian J Crit Care Med 2020;24(9):838-846.

Systematic and Statistical Review of Coronavirus Disease 19 Treatment Trials

The following systematic review and meta-analysis compile the current data regarding human controlled COVID-19 treatment trials. An electronic search of the literature compiled studies pertaining to human controlled treatment trials with COVID-19. Medications assessed included lopinavir/ritonavir, arbidol, hydroxychloroquine, tocilizumab, favipiravir, heparin, and dexamethasone. Statistical analyses were performed for common viral clearance endpoints whenever possible. Lopinavir/ritonavir showed no significant effect on viral clearance for COVID-19 cases (OR 0.95 [95% CI 0.50-1.83]). Hydroxychloroquine also showed no significant effect on COVID-19 viral clearance rates (OR 2.16 [95% CI 0.80-5.84]). Arbidol showed no 7-day (OR 1.63 [95% CI 0.76-3.50]) or 14-day viral (OR 5.37 [95% CI 0.35-83.30]) clearance difference compared to lopinavir/ritonavir. Review of literature showed no significant clinical improvement with lopinavir/ritonavir, arbidol, hydroxychloroquine, or remdesivir. Tocilizumab showed mixed results regarding survival. Favipiravir showed quicker symptom improvement compared to lopinavir/ritonavir and arbidol. Heparin and dexamethasone showed improvement with severe COVID-19 cases requiring supplemental oxygenation. Current medications do not show significant effect on COVID-19 viral clearance rates. Tocilizumab showed mixed results regarding survival. Favipiravir shows favorable results compared to other tested medications. Heparin and dexamethasone show benefit especially for severe COVID-19 cases.

Pharmacotherapics Advice in Guidelines for COVID-19

Since December 2019 to May 2020, coronavirus disease 2019 (COVID-19) has infected over 6 million people worldwide. Due to its sudden and rapid outbreak, effective treatment for COVID-19 is scarce. Based on national clinical trials of novel treatments, China, Italy, Germany, and other countries and organizations have published multiple guidelines for COVID-19 and advised many medicines, such as chloroquine and tocilizumab. In this paper, we summarize the pharmacotherapy for COVID-19 according to those guidelines, highlight updates of the pharmacotherapy guidelines, and review the efficacy and safety of the indicated anti-COVID-19 drugs.

Potential of Arbidol for Post-exposure Prophylaxis of COVID-19 Transmission: A Preliminary Report of a Retrospective Cohort Study

The efficient transmission of severe acute respiratory syndrome-2 coronavirus (SARS-CoV-2) from patients to health care workers or family members has been a worrisome and prominent feature of the ongoing outbreak. On the basis of clinical practice and in-vitro studies, we postulated that post-exposure prophylaxis (PEP) using Arbidol is associated with decreased infection among individuals exposed to confirmed cases of COVID-19 infection. We conducted a retrospective cohort study on family members and health care workers who were exposed to patients confirmed to have SARS-CoV-2 infection by real-time RT-PCR and chest computed tomography (CT) from January 1 to January 16, 2020. The last follow-up date was Feb. 26, 2020. The emergence of fever and/or respiratory symptoms after exposure to the primary case was collected. The correlations between post-exposure prophylaxis and infection in household contacts and health care workers were respectively analyzed. A total of 66 members in 27 families and 124 health care workers had evidence of close exposure to patients with confirmed COVID-19. The Cox regression based on the data of the family members and health care workers with Arbidol or not showed that Arbidol PEP was a protective factor against the development of COVID-19 (HR 0.025, 95% CI 0.003–0.209, P=0.0006 for family members and HR 0.056, 95% CI 0.005–0.662, P=0.0221 for health care workers). Our findings suggest Arbidol could reduce the infection risk of the novel coronavirus in hospital and family settings. This treatment should be promoted for PEP use and should be the subject of further investigation.

Efficacy and Safety of Lopinavir/Ritonavir or Arbidol in Adult Patients with Mild/Moderate COVID-19: An Exploratory Randomized Controlled Trial

Background

Antiviral therapies against the novel coronavirus SARS-CoV-2, which has caused a global pandemic of respiratory illness called COVID-19, are still lacking.

Methods

Our study (ClinicalTrials.gov: NCT04252885, named ELACOI), was an exploratory randomized (2:2:1) controlled trial assessing the efficacy and safety of lopinavir/ritonavir (LPV/r) or arbidol monotherapy for treating patients with mild/moderate COVID-19.

Findings

This study successfully enrolled 86 patients with mild/moderate COVID-19, with 34 randomly assigned to receive LPV/r, 35 to arbidol, and 17 with no antiviral medication as control. Baseline characteristics of the three groups were comparable. The primary endpoint, the rate of positive-to-negative conversion of SARS-CoV-2 nucleic acid, was similar between groups (all p > 0.05). There were no differences between groups in the secondary endpoints, the rates of antipyresis, cough alleviation, or improvement of chest computed tomography (CT) at days 7 or 14 (all p > 0.05). At day 7, 8 (23.5%) patients in the LPV/r group, 3 (8.6%) in the arbidol group, and 2 (11.8%) in the control group showed a deterioration in clinical status from moderate to severe/critical (p = 0.206). Overall, 12 (35.3%) patients in the LPV/r group and 5 (14.3%) in the arbidol group experienced adverse events during the follow-up period. No apparent adverse event occurred in the control group.

Conclusions

LPV/r or arbidol monotherapy present little benefit for improving the clinical outcome of patients hospitalized with mild/moderate COVID-19 over supportive care.

Funding

This study was supported by project 2018ZX10302103-002, 2017ZX10202102-003-004, and Infectious Disease Specialty of Guangzhou High-level Clinical Key Specialty (2019-2021).

Effective therapies against COVID-19 are urgently needed

Lopinavir/ritonavir and arbidol were tested in patients with mild/moderate COVID-19

Neither treatment shows significant advantage over supportive care

The coronavirus SARS-CoV-2 is causing the current COVID-19 pandemic, which has affected over 1 million people worldwide. As the scientific community researches new treatments against the disease, drugs that have already been approved for other viruses are also being tested. Here, clinicians from Guangzhou Medical University tested lopinavir/ritonavir and arbidol, which are currently used against HIV-1 and influenza, respectively, in patients with mild or moderate COVID-19. The authors show that neither drug improves the recovery compared to standard care, suggesting that treatment with either drug may not be beneficial against COVID-19 and other therapies may be a more effective choice.

Antioxidant Potential of Antiviral Drug Umifenovir

Free radical reactions play an important role in biological functions of living systems. The balance between oxidants and antioxidants is necessary for the normal homeostasis of cells and organisms. Experimental works demonstrate the role of oxidative stress that is caused by influenza virus as well as the toxic effects of some antiviral drugs. Therefore, antiviral drugs should be characterized by its pro- and antioxidant activity, because it can affect its therapeutic efficiency. The aim of the study was to quantify the antioxidant capacity and propose the mechanism of the antioxidant effect of the antiviral drug Umifenovir (Arbidol®). The kinetic chemiluminescence with the 2,2'-azobis (2-amidinopropane) dihydrochloride + luminol system was used to quantify the antioxidant capacity of Umifenovir relative to the standard compound Trolox. With computer simulation, the reaction scheme and rate constants were proposed. The antioxidant capacity of 0.9 μM Umifenovir (maximum concentration of Umifenovir in blood after oral administration of 200 mg) was as high as 1.65 ± 0.18 μM of Trolox. Thus, the total antioxidant capacity of Umifenovir is comparable to the antioxidant capacity of Trolox. Unlike Trolox, Umifenovir reacts with free radicals in two stages. For Trolox, the free radical scavenging rate constant was k = 2000 nM-1 min.-1, for Umifenovir k1 = 300 nM-1min.-1, k2 = 4 nM-1min.-1. Slower kinetics of Umifenovir provides the prolonged antioxidant effect when compared to Trolox. This phenomenon can make a serious contribution to the compensation of oxidative stress that is caused by a viral disease and the therapeutic effect of the drug.

Clinical efficacy of umifenovir in influenza and ARVI (study ARBITR)

AIM

The aim of the study is to obtain additional data on safety and therapeutic efficacy of the antiviral drug Arbidol (umifenovir) in patients with a diagnosis of influenza and common cold.

MATERIALS AND METHODS

Double-blind, randomized, placebo-controlled clinical study investigating efficacy and safety of Arbidol (umifenovir) in Treatment and Prophylaxis of Influenza and Common Cold (ARBITR) IV phase started in November 2011 and completed in April 2016 on the basis of 15 research centers in various regions of the Russian Federation. A total of 359 patients, aged 18 to 65 years with influenza or acute respiratory tract infection, of no more than 36 hours' duration were enrolled in the study. Patients were randomized into two groups: a group of patients (therapy group) treated by Arbidol (umifenovir) at a dosage of 800 mg/day (2 capsules) for 5 days (n=181), and a group of patients receiving placebo 4 times a day for 5 days (n=178). The primary outcome measures of the study were the duration of clinical illness among patients with common cold and influenza/ARVI, the duration and severity of the main symptoms. Number of clinical complications associated with influenza and common cold was assessed as a secondary outcome. Safety was assessed by analyzing number of adverse events that are probably or definitely related to Arbidol, assessing vital signs, examining the physical condition of patients and general clinical laboratory parameters.

RESULTS

In the group treated by umifenovir, the number of full recover patients on the 4th day from the disease onset were significantly differed from the number of such cases in the placebo group. The number of cases of complete recovery after 96 hours was 98 patients (54.1%) and 77 (43.3%), p&lt;0.05, and after 108 hours - 117 (64.6%) and 98 (55.1%), p&lt;0.05. Duration of intoxication was reduced with umifenovir compared to placebo, amounted to 77.76 and 88.91 hours, respectively, p=0.013. The duration of all intoxication syndrome symptoms was also lower in the group receiving umifenovir. Thus, in the therapy group and placebo group, these parameters were respectively: fever duration - 67.96 and 75.32 hours (p=0.037), muscle pain - 52.23 and 59.08 hours (p=0.023), headache - 52.78 and 63.28 hours (p=0.013), weakness - 76.90 and 88.89 hours (p=0.008). The incidence of complications in the umifenovir group was 3.8%, in the placebo group 5.62%. Cases of acute tracheobronchitis was an increase in the placebo group (p&lt;0.02). Umifenovir and placebo were well tolerated. A total of 42 cases of adverse events were registered in 11 patients in the treatment group and in 18 patients in the placebo group, which were not associated with umifenovir or placebo.

CONCLUSION

The results of this study indicate umifenovir safety and confirm its effectiveness to the treatment of influenza and other acute respiratory viral infections in adult patients. It was found that effect of umifenovir in the treatment of influenza in adults is most pronounced in the acute stage of the disease and appears in the reduction of time to resolution of all symptoms of the disease, reducing the severity of symptoms of the disease.

Current and Novel Approaches in Influenza Management

Influenza is a disease that poses a significant health burden worldwide. Vaccination is the best way to prevent influenza virus infections. However, conventional vaccines are only effective for a short period of time due to the propensity of influenza viruses to undergo antigenic drift and antigenic shift. The efficacy of these vaccines is uncertain from year-to-year due to potential mismatch between the circulating viruses and vaccine strains, and mutations arising due to egg adaptation. Subsequently, the inability to store these vaccines long-term and vaccine shortages are challenges that need to be overcome. Conventional vaccines also have variable efficacies for certain populations, including the young, old, and immunocompromised. This warrants for diverse efficacious vaccine developmental approaches, involving both active and passive immunization. As opposed to active immunization platforms (requiring the use of whole or portions of pathogens as vaccines), the rapidly developing passive immunization involves administration of either pathogen-specific or broadly acting antibodies against a kind or class of pathogens as a treatment to corresponding acute infection. Several antibodies with broadly acting capacities have been discovered that may serve as means to suppress influenza viral infection and allow the process of natural immunity to engage opsonized pathogens whilst boosting immune system by antibody-dependent mechanisms that bridge the innate and adaptive arms. By that; passive immunotherapeutics approach assumes a robust tool that could aid control of influenza viruses. In this review, we comment on some improvements in influenza management and promising vaccine development platforms with an emphasis on the protective capacity of passive immunotherapeutics especially when coupled with the use of antivirals in the management of influenza infection.

The broad-spectrum antiviral drug arbidol inhibits foot-and-mouth disease virus genome replication

Arbidol (ARB, also known as umifenovir) is used clinically in several countries as an anti-influenza virus drug. ARB inhibits multiple enveloped viruses in vitro and the primary mode of action is inhibition of virus entry and/or fusion of viral membranes with intracellular endosomal membranes. ARB is also an effective inhibitor of non-enveloped poliovirus types 1 and 3. In the current report, we evaluate the antiviral potential of ARB against another picornavirus, foot-and-mouth disease virus (FMDV), a member of the genus Aphthovirus and an important veterinary pathogen. ARB inhibits the replication of FMDV RNA sub-genomic replicons. ARB inhibition of FMDV RNA replication is not a result of generalized inhibition of cellular uptake of cargo, such as transfected DNA, and ARB can be added to cells up to 3 h post-transfection of FMDV RNA replicons and still inhibit FMDV replication. ARB prevents the recovery of FMDV replication upon withdrawal of the replication inhibitor guanidine hydrochloride (GuHCl). Although restoration of FMDV replication is known to require de novo protein synthesis upon GuHCl removal, ARB does not suppress cellular translation or FMDV internal ribosome entry site (IRES)-driven translation. ARB also inhibits infection with the related Aphthovirus, equine rhinitis A virus (ERAV). Collectively, the data demonstrate that ARB can inhibit some non-enveloped picornaviruses. The data are consistent with inhibition of picornavirus genome replication, possibly via the disruption of intracellular membranes on which replication complexes are located.

In silico structural elucidation of RNA-dependent RNA polymerase towards the identification of potential Crimean-Congo Hemorrhagic Fever Virus inhibitors

The Crimean-Congo Hemorrhagic Fever virus (CCHFV) is a segmented negative single-stranded RNA virus (-ssRNA) which causes severe hemorrhagic fever in humans with a mortality rate of ~50%. To date, no vaccine has been approved. Treatment is limited to supportive care with few investigational drugs in practice. Previous studies have identified viral RNA dependent RNA Polymerase (RdRp) as a potential drug target due to its significant role in viral replication and transcription. Since no crystal structure is available yet, we report the structural elucidation of CCHFV-RdRp by in-depth homology modeling. Even with low sequence identity, the generated model suggests a similar overall structure as previously reported RdRps. More specifically, the model suggests the presence of structural/functional conserved RdRp motifs for polymerase function, the configuration of uniform spatial arrangement of core RdRp sub-domains, and predicted positively charged entry/exit tunnels, as seen in sNSV polymerases. Extensive pharmacophore modeling based on per-residue energy contribution with investigational drugs allowed the concise mapping of pharmacophoric features and identified potential hits. The combination of pharmacophoric features with interaction energy analysis revealed functionally important residues in the conserved motifs together with in silico predicted common inhibitory binding modes with highly potent reference compounds.

The Antiviral Drug Arbidol Inhibits Zika Virus

There are many emerging and re-emerging globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Arbidol (ARB, umifenovir), used clinically for decades in several countries as an anti-influenza virus drug, inhibits many other viruses. In the current study, we show that ARB inhibits six different isolates of Zika virus (ZIKV), including African and Asian lineage viruses in multiple cell lines and primary human vaginal and cervical epithelial cells. ARB protects against ZIKV-induced cytopathic effects. Time of addition studies indicate that ARB is most effective at suppressing ZIKV when added to cells prior to infection. Moreover, ARB inhibits pseudoviruses expressing the ZIKV Envelope glycoprotein. Thus, ARB, a broadly acting anti-viral agent with a well-established safety profile, inhibits ZIKV, likely by blocking viral entry.

Antiviral activity of arbidol hydrochloride against herpes simplex virus I in vitro and in vivo

Herpes simplex virus type 1 (HSV-1) causes significant human diseases ranging from skin lesions to encephalitis, especially in neonates and immunocompromised hosts. The discovery of novel anti-HSV-1 drugs with low toxicity is required for public health. Arbidol hydrochloride (ARB) is an indole derivative molecule with broad-spectrum antiviral activity. In this study, the antiviral effects of ARB against HSV-1 infection were evaluated in vitro and in vivo. The results showed that ARB presents significant inhibitory effect on HSV-1 plaque formation and generation of progeny virus, with EC50 values (50% effective concentration) of 5.39 µg/mL (10.49 µM) and 2.26 µg/mL (4.40 µM), respectively. Moreover, time-of-addition and time-of-removal assays further suggested that ARB has viral inhibitory effects when added up to 12 h post-infection (p.i.), which could be further corroborated by determining the expression of viral immediate-early (ICP4, ICP22 and ICP27), early (ICP8 and UL42) and late (gB, gD, gH, VP1/2 and VP16) genes by real-time quantitative PCR as well as the expression of viral protein ICP4 and ICP8 at 6 h and 12 h p.i. Results of the in vivo study showed that ARB could reduce guinea pig skin lesions caused by HSV-1 infection. Conclusively, this report offers new perspectives in the search for therapeutic measures in the treatment of HSV-1 infection.

[Pharmacoepidemiological study of the course of influenza and other acute respiratory viral infections in risk groups]

AIM

To identify risk factors (RFs) for the development of bacterial complications and the prolonged course of influenza and other acute respiratory viral infections (ARVIs) among inpatients treated in Russian healthcare facilities in the post-pandemic period; to determine the clinical presentation of the disease (flu-like syndrome) in risk-group people and to evaluate the efficacy of antiviral therapy with arbidol (umifenovir).

MATERIAL AND METHODS

The investigators retrospectively analyzed randomly selected medical records of inpatients with influenza and other ARVI in 88 hospitals from 50 regions of the Russian Federation: those of 3532 and 1755 patients in the 2010-2011 and 2014-2015 seasons, respectively, by applying parametric and nonparametric statistical methods.

RESULTS

The built database of patients with influenza-like syndrome contained data from the histories of 2072 men and 2537 women, of whom there were 317 (12.49%) pregnant women; gender evidence was not given in the medical records for 678 patients. 382 (7.2%) were vaccinated against influenza. 1528 (28.9%) people were admitted to hospital with various complications. Information on laboratory tests was available in 1691 (31.98%) patients; of these, 1291 (76.4%) were detected to have influenza and other respiratory viruses. Influenza viruses were found in 1026 (60.7%) examinees; influenza A viruses in 712 (42.1%) people while pandemic strain of swine influenza A/H1N1 and A/H3N2 viruses was detected in 487 (28.8%) and 107 (6.3%) patients, respectively; influenza A subtype was indicated in 118 (7%) persons with laboratory-confirmed influenza virus. Influenza B viruses were found in 314 (18.6%) examinees. Other types of respiratory viruses were detected in 265 (15.7%) patients. The body mass index exceeded 30 kg/m2 in 227 (4.3%) patients. Single-factor analysis of variance revealed factors influencing the course of flu-like syndrome and identified risk groups: children younger than 2 years old and adults over 65, pregnant women, and people with chronic somatic diseases and obesity. The high-risk groups exhibited a more severe course of flu-like syndrome than did the patients outside the risk groups. The incidence of complications was higher, especially in the under 2-year-year-old children and in patients with endocrine, metabolic, or respiratory diseases, with a large proportion of complications being pneumonia. The efficacy of antiviral therapy was higher in the elderly, patients with chronic diseases, and pregnant women than in patients not at risk. In patients treated with umifenovir (provided that it was administered in the first 48 hours after disease onset), the duration of fever and frequency of complications proved to be lower than those in patients who did not receive antiviral therapy.

CONCLUSION

The FRs for influenza and ARVI complications are patient's age (children under 3 years of age and adults older than 65 years), the presence of chronic somatic diseases, and pregnancy. Patients with endocrine, eating, metabolic (including obesity), circulatory, and respiratory disorders are at high risk for influenza and ARVI complications. Umifenovir therapy substantially reduces the duration of fever and risk of complications, especially in patients with laboratory-confirmed influenza infection.

Inhibition of the infectivity and inflammatory response of influenza virus by Arbidol hydrochloride in vitro and in vivo (mice and ferret)

Influenza virus infections are the main contagious respiratory disease with high levels of morbidity and mortality worldwide. Antiviral drugs are indispensable for the prophylaxis and treatment of influenza and other respiratory viral infections. In this study, the Arbidol hydrochloride (ARB), which has been licensed in Russia and China, is used to investigate its anti-viral and anti-inflammatory efficacy in vitro and in vivo. The antiviral results in vitro showed that ARB had a better inhibition on Influenza virus A/PR/8/34 (H1N1), A/Guangdong/GIRD07/09 (H1N1), A/Aichi/2/68 (H3N2), A/HK/Y280/97 (H9N2) with IC₅₀ ranging from 4.4 to 12.1μM. The further mechanisms study demonstrated that ARB is able to inhibit hemagglutinin-mediated hemolysis at concentration of 3.91-15.63μg/mL. The anti-inflammatory efficacy in vitro indicated that IL-6, IP-10, MCP-1, RANTES and TNF-α levels were diminished by ARB at concentrations of 22.6 and 18.8μM. The in vivo results in mice model displayed that the survival rates of mice administered 25mg/mL and 45mg/mL ARB were 40% and 50% respectively. And also, ARB can inhibit the decrease of body weight at 45mg/mL and inhibit the increase of mice lung index at 25mg/mL and 45mg/mL comparing to virus group. In ferret model, the ARB-treated ferrets showed a fever that peaked at 2 dpi and gradually decreased beginning at 3 dpi while relatively high temperatures were observed until 4 dpi in the virus group. The ARB-treated group scored 0-1 in the activity level at 2 dpi and 3 dpi at all time points. The transcription levels of cytokines in the respiratory tract of ferrets were detected at 3 dpi. Several proinflammatory cytokines induced by influenza (IL-10, TNF-α, IL-8 and IL-6) were down-regulated by post-treatment with ARB. The histopathological results of ferret lung displayed that ARB can alleviate the influenza virus induced lung lesions. Our results clarified the activity of ARB in both suppressing virus propagation and modulating the expression of inflammatory cytokines in vitro and in vivo, it can be as an effective drug to treat the influenza virus infection.

Effect of solvent type and concentration on size and morphology of arbidol microparticles obtained by supercritical antisolvent precipitation

The capability of arbidol microparticle preparation by supercritical antisolvent (SAS) precipitation was demonstrated. A nonmonotonic dependence of the average particle size on the concentration was found, while the position of the minimum is dependent on the type of solvent used. It is possible to prepare Arbidol particles of various morphology and size from several microns to several hundred microns depending on the conditions.

Structural basis of influenza virus fusion inhibition by the antiviral drug Arbidol

The broad-spectrum antiviral drug Arbidol shows efficacy against influenza viruses by targeting the hemagglutinin (HA) fusion machinery. However, the structural basis of the mechanism underlying fusion inhibition by Arbidol has remained obscure, thereby hindering its further development as a specific and optimized influenza therapeutic. We determined crystal structures of Arbidol in complex with influenza virus HA from pandemic 1968 H3N2 and recent 2013 H7N9 viruses. Arbidol binds in a hydrophobic cavity in the HA trimer stem at the interface between two protomers. This cavity is distal to the conserved epitope targeted by broadly neutralizing stem antibodies and is ∼16 Å from the fusion peptide. Arbidol primarily makes hydrophobic interactions with the binding site but also induces some conformational rearrangements to form a network of inter- and intraprotomer salt bridges. By functioning as molecular glue, Arbidol stabilizes the prefusion conformation of HA that inhibits the large conformational rearrangements associated with membrane fusion in the low pH of the endosome. This unique binding mode compared with the small-molecule inhibitors of other class I fusion proteins enhances our understanding of how small molecules can function as fusion inhibitors and guides the development of broad-spectrum therapeutics against influenza virus.

The delivery of arbidol by salt engineering: synthesis, physicochemical properties and pharmacokinetics

The aim of the present study was to evaluate the feasibility of using the methanesulfonic salt of arbidol in order to improve its aqueous solubility and thus oral bioavailability. Arbidol mesylate (AM) was synthesized and then characterized using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), and its apparent solubility and octanol-water partition coefficient were also studied. The results of NMR, IR, PXRD, SEM and DSC tests confirmed the salt formation. The apparent solubility of AM in water was 32-fold higher than that of the commercial product. A superior pH-dependent profile and an improved dissolution rate of AM were obtained in a variety of solutions with different pH values. In addition, AM exhibited a relatively higher peak plasma concentration (1460 versus 1297 ng/mL) and an increased AUC_0-t (2475 versus 1277 ng/mL × h) when comparing with the commercial product, indicating the improved bioavailability of the drug. This study suggests that AM may be able to improve the therapeutic efficacy of arbidol, which rendering it to be a promising candidate for further development.

The Location of the Protonated and Unprotonated Forms of Arbidol in the Membrane: A Molecular Dynamics Study

Abstract

Arbidol is a potent broad-spectrum antiviral molecule for the treatment and prophylaxis of many viral infections. Viruses that can be inhibited by arbidol include enveloped and non-enveloped viruses, RNA and DNA viruses, as well as pH-independent and pH-dependent ones. These differences in viral types highlight the broad spectrum of Arb antiviral activity and, therefore, it must affect a common viral critical step. Arbidol incorporates rapidly into biological membranes, and some of its antiviral effects might be related to its capacity to interact with and locate into the membrane. However, no information is available of the molecular basis of its antiviral mechanism/s. We have aimed to locate the protonated (Arp) and unprotonated (Arb) forms of arbidol in a model membrane system. Both Arb and Arp locate in between the hydrocarbon acyl chains of the phospholipids but its specific location and molecular interactions differ from each other. Whereas both Arb and Arp average location in the membrane palisade is a similar one, Arb tends to be perpendicular to the membrane surface, whereas Arp tends to be parallel to it. Furthermore, Arp, in contrast to Arb, seems to interact stronger with POPG than with POPC, implying the existence of a specific interaction between Arp, the protonated from, with negatively charged phospholipids. This data would suggest that the active molecule of arbidol in the membrane is the protonated one, i.e., the positively charged molecule. The broad antiviral activity of arbidol would be defined by the perturbation it exerts on membrane structure and therefore membrane functioning.

Graphical Abstract

Electronic supplementary material

The online version of this article (doi:10.1007/s00232-016-9876-3) contains supplementary material, which is available to authorized users.

Virus susceptibility and clinical effectiveness of anti-influenza drugs during the 2010-2011 influenza season in Russia

BACKGROUND

Antiviral drugs are critical adjuncts to influenza vaccination. This study determined the in vitro susceptibilities of influenza A and B viruses isolated in the 2010-2011 season in Russia to the neuraminidase inhibitor oseltamivir and the hemagglutinin fusion inhibitor umifenovir and clinical efficacy of this antiviral drugs in this season.

METHODS

The antiviral potency of these drugs against A(H1N1)pdm09 virus in mice was assessed. Importantly, the clinical effectiveness of oseltamivir and umifenovir was evaluated in a retrospective study conducted in 26 regions of Russia.

RESULTS

All tested viruses (n=36) were susceptible to oseltamivir and umifenovir in vitro. Oseltamivir (10mg/kg/day) and umifenovir (60 mg/kg/day) significantly increased the survival of mice challenged with A/California/04/2009 (H1N1)pdm09 virus (p<0.05). Influenza infection was laboratory-confirmed in 442 patients among 1462 patients hospitalized with acute respiratory infections. The treatment of influenza-infected patients within 48h of symptom onset with oseltamivir and umifenovir was associated with a significant decrease in the duration of illness (2-3 days) and symptoms (p<0.001). Pneumonia was observed in none of the patients treated with oseltamivir and in 0.3% of the patients treated with umifenovir, compared to 23.7% of patients who did not receive antiviral therapy (p<0.001).

CONCLUSIONS

This study provided experimental and clinical evidence of the efficacy of oseltamivir and umifenovir against influenza viruses, representatives of which have continued to circulate in post-pandemic seasons.

Entry inhibitors: New advances in HCV treatment

Hepatitis C virus (HCV) infection affects approximately 3% of the world's population and causes chronic liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. Although current antiviral therapy comprising direct-acting antivirals (DAAs) can achieve a quite satisfying sustained virological response (SVR) rate, it is still limited by viral resistance, long treatment duration, combined adverse reactions, and high costs. Moreover, the currently marketed antivirals fail to prevent graft reinfections in HCV patients who receive liver transplantations, probably due to the cell-to-cell transmission of the virus, which is also one of the main reasons behind treatment failure. HCV entry is a highly orchestrated process involving initial attachment and binding, post-binding interactions with host cell factors, internalization, and fusion between the virion and the host cell membrane. Together, these processes provide multiple novel and promising targets for antiviral therapy. Most entry inhibitors target host cell components with high genetic barriers and eliminate viral infection from the very beginning of the viral life cycle. In future, the addition of entry inhibitors to a combination of treatment regimens might optimize and widen the prevention and treatment of HCV infection. This review summarizes the molecular mechanisms and prospects of the current preclinical and clinical development of antiviral agents targeting HCV entry.

The Synthetic Antiviral Drug Arbidol Inhibits Globally Prevalent Pathogenic Viruses

Arbidol (ARB) is a synthetic antiviral originally developed to combat influenza viruses. ARB is currently used clinically in several countries but not in North America. We have previously shown that ARB inhibits in vitro hepatitis C virus (HCV) by blocking HCV entry and replication. In this report, we expand the list of viruses that are inhibited by ARB and demonstrate that ARB suppresses in vitro infection of mammalian cells with Ebola virus (EBOV), Tacaribe arenavirus, and human herpesvirus 8 (HHV-8). We also confirm suppression of hepatitis B virus and poliovirus by ARB. ARB inhibited EBOV Zaire Kikwit infection when added before or at the same time as virus infection and was less effective when added 24 h after EBOV infection. Experiments with recombinant vesicular stomatitis virus (VSV) expressing the EBOV Zaire glycoprotein showed that infection was inhibited by ARB at early stages, most likely at the level of viral entry into host cells. ARB inhibited HHV-8 replication to a similar degree as cidofovir. Our data broaden the spectrum of antiviral efficacy of ARB to include globally prevalent viruses that cause significant morbidity and mortality.

IMPORTANCE

There are many globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Some of these viruses, such as Ebola virus or members of the arenavirus family, rapidly cause severe hemorrhagic diseases that can be fatal. Other viruses, such as hepatitis B virus or human herpesvirus 8 (HHV-8), establish persistent infections that cause chronic illnesses, including cancer. Thus, finding an affordable, effective, and safe drug that blocks many viruses remains an unmet medical need. The antiviral drug arbidol (ARB), already in clinical use in several countries as an anti-influenza treatment, has been previously shown to suppress the growth of many viruses. In this report, we expand the list of viruses that are blocked by ARB in a laboratory setting to include Ebola virus, Tacaribe arenavirus, and HHV-8, and we propose ARB as a broad-spectrum antiviral drug that may be useful against hemorrhagic viruses.

Aureonitol, a Fungi-Derived Tetrahydrofuran, Inhibits Influenza Replication by Targeting Its Surface Glycoprotein Hemagglutinin

The influenza virus causes acute respiratory infections, leading to high morbidity and mortality in groups of patients at higher risk. Antiviral drugs represent the first line of defense against influenza, both for seasonal infections and pandemic outbreaks. Two main classes of drugs against influenza are in clinical use: M2-channel blockers and neuraminidase inhibitors. Nevertheless, because influenza strains that are resistant to these antivirals have been described, the search for novel compounds with different mechanisms of action is necessary. Here, we investigated the anti-influenza activity of a fungi-derived natural product, aureonitol. This compound inhibited influenza A and B virus replication. This compound was more effective against influenza A(H3N2), with an EC₅₀ of 100 nM. Aureonitol cytoxicity was also very low, with a CC₅₀ value of 1426 μM. Aureonitol inhibited influenza hemagglutination and, consequently, significantly impaired virus adsorption. Molecular modeling studies revealed that aureonitol docked in the sialic acid binding site of hemagglutinin, forming hydrogen bonds with highly conserved residues. Altogether, our results indicate that the chemical structure of aureonitol is promising for future anti-influenza drug design.

[Clinical efficacy of arbidol (umifenovir) in the therapy of influenza in adults: preliminary results of the multicenter double-blind randomized placebo-controlled study ARBITR]

AIM

To evaluate the efficacy and safety of Arbidol (umifenovir) in adult patients with influenza.

SUBJECTS AND METHODS

The analysis of the preliminary results of the multicenter double-blind randomized placebo-controlled post-marketing study ARBITR was performed. A total of 293 adults aged 18 to 65 years with influenza or acute respiratory tract infection of no more than 36 hours' duration were enrolled in the study. Individuals were randomized into 2 treatment groups: oral umifenovir 200 mg four times daily for 5 days or placebo four times daily for 5 days. The efficacy endpoints were time to resolution of all symptoms, severity of symptoms and illness, durations of virus shedding.

RESULTS

The efficacy of umifenovir was evaluated in the group of 119 (40.6%) patients with influenza: 45 patients with laboratory-confirmed influenza and 74 patients whom diagnosis of influenza was made based on clinical and epidemiological data. Umifenovir had influence on the time to resolution of all symptoms. All symptoms were resolved within the first 60 hours after therapy initiation in 23.8% patients with laboratory-confirmed influenza in the umifenovir group and it was 5.7 times greater compared to placebo group (4.2%) (p < 0.05). Severity of illness, catarrhal symptoms and intoxication was reduced with umifenovir compared to placebo, reducing of severity was most evidently observed within the first 2-3 days following the therapy initiation. Umifenovir had a significant effect on viral shedding. The proportion of patients still shedding influenza virus on day 4 was significantly reduced in the umifenovir group compared to placebo (25 vs 53%, respectively; p < 0.05).

CONCLUSION

It was found that the effect of umifenovir in the treatment of influenza in adults is most pronounced in the acute stage of the disease and appears in the reduction of time to resolution of all symptoms of the disease, reducing the severity of symptoms of the disease and durations of virus shedding.