Peramivir: A Review in Uncomplicated Influenza

Genetic characterization of influenza B virus and oseltamivir resistance in pediatric patients with acute respiratory infections: a cross-sectional study

Influenza virus neuraminidase inhibitors (NAIs) drug usage can result in NAI resistance, especially in children and individuals with weakened immune systems. The aim of the present study was to identify NAI-resistant variants of IBV and to introduce probable novel mutations, phylogenetic study, and its epitope mapping based on NA gene in patients from Shiraz, Iran. A cross-sectional study was conducted between 2017 and 2018 on symptomatic children. A real-time PCR was run for IBV screening. Then, making use of direct sequencing, amplified 1401 bases of NA gene and phylogenetic tree reconstructed. Epitopes were predicted using ABCpred server. From among a total of 235 specimens, 9.7% were identified with IBV infection. Of them, sequence of NA gene for 17 isolates were analyzed. Phylogenetic analysis showed that 15 isolates belonged to Yamagata clade 3 Wisconsin/01-like subclade and 2 were related to Victoria clade 1 Brisbane/60-like subclade (Vic-1A-2). NA gene sequence analysis showed a total of 52 substitutions in which 27 were for BVic and 37 were for BYam isolates and 19 were novel substitutions. Only one substitution (S198N) was found in NA active site and T49M, I120V, N198S, N219K, S295R, D320K N340D, E358K, D384G, and D463N were found as probable resistance variants to NAIs. Epitope mapping showed some major differences in our isolates NA gene. Present study was one of the rare comprehensive studies conducted in Shiraz/Iran on IBV resistant associated variants to NAIs. We reported 11.7% mutation in NA active site and some probable NAIs resistant mutations. Epitope mapping confirmed major changes in NA gene which needs broader studies to confirm.

Antiviral drug development by targeting RNA binding site, oligomerization and nuclear export of influenza nucleoprotein

The quasispecies of the influenza virus poses a significant challenge for developing effective therapies. Current antiviral drugs such as oseltamivir, zanamivir, peramivir and baloxavir marboxil along with seasonal vaccines have limitations due to viral variability caused by antigenic drift and shift as well as the development of drug resistance. Therefore, there is a clear need for novel antiviral agents targeting alternative mechanisms, either independently or in combination with existing modalities, to reduce the impact of influenza virus-related infections. The influenza nucleoprotein (NP) is a key component of the viral ribonucleoprotein complex. The multifaceted nature of the NP makes it an attractive target for antiviral intervention. Recent reports have identified inhibitors that specifically target this protein. Recognizing the importance of developing influenza treatments for potential pandemics, this review explores the structural and functional aspects of NP and highlights its potential as an emerging target for anti-influenza drugs. We discuss various strategies for targeting NP, including RNA binding, oligomerization, and nuclear export, and also consider the potential of NP-based vaccines. Overall, this review provides insights into recent developments and future perspectives on targeting influenza NP for antiviral therapies.

Treating influenza with neuraminidase inhibitors: an update of the literature

INTRODUCTION

Influenza affects individuals of all ages and poses a significant threat during pandemics, epidemics, and sporadic outbreaks. Neuraminidase inhibitors (NAIs) are currently the first choice in the treatment and prevention of influenza, but their use can be hindered by viral resistance.

AREAS COVERED

This review summarizes current NAIs pharmacological profiles, their current place in therapy, and the mechanisms of viral resistance and outlines possible new indications, ways of administration, and novel candidate NAIs compounds.

EXPERT OPINION

NAIs represent a versatile group of compounds with diverse administration methods and pharmacokinetics. While the prevalence of influenza virus resistance to NAIs remains low, there is heightened vigilance due to the pandemic potential of influenza. Several novel NAIs and derivatives are currently under assessment at various stages of development for the treatment and prevention of influenza.

Modular Biomimetic Strategy Enables Discovery and SAR Exploration of Oxime Macrocycles as Influenza A Virus (H1N1) Inhibitors

Although vaccination remains the prevalent prophylactic means for controlling Influenza A virus (IAV) infections, novel structural antivirus small-molecule drugs with new mechanisms of action for treating IAV are highly desirable. Herein, we describe a modular biomimetic strategy to expeditiously achieve a new class of macrocycles featuring oxime, which might target the hemagglutinin (HA)-mediated IAV entry into the host cells. SAR analysis revealed that the size and linker of the macrocycles play an important role in improving potency. Particularly, as a 14-membered macrocyclic oxime, 37 exhibited potent inhibitory activity against IAV H1N1 with an EC50 value of 23 nM and low cytotoxicity, which alleviated cytopathic effects and protected cell survival obviously after H1N1 infection. Furthermore, 37 showed significant synergistic activity with neuraminidase inhibitor oseltamivir in vitro.

Design, synthesis and biological evaluation of sulfamethazine derivatives as potent neuraminidase inhibitors

Aim: The purpose of this study is to design and synthesize a new series of sulfamethazine derivatives as potent neuraminidase inhibitors. Materials & methods: A sulfamethazine lead compound, ZINC670537, was first identified by structure-based virtual screening technique, then some novel inhibitors X1-X10 based on ZINC670537 were designed and synthesized. Results: Compound X3 exerts the most good potency in inhibiting the wild-type H5N1 NA (IC50 = 6.74 μM) and the H274Y mutant NA (IC50 = 21.09 μM). 150-cavity occupation is very important in determining activities of these inhibitors. The sulfamethazine moiety also plays an important role. Conclusion: Compound X3 maybe regard as a good anti-influenza candidate to preform further study.

Retracted and republished from: "The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs"

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the Food and Drug Administration are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. These recommended antivirals are currently effective for major subtypes of IVs as the compounds target conserved domains in neuraminidase or polymerase acidic (PA) protein. However, this trend may gradually change due to the selection of antiviral drugs and the natural evolution of IVs. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Latest developments in early diagnosis and specific treatment of severe influenza infection

Influenza pandemics are unpredictable recurrent events with global health, economic, and social consequences. The objective of this review is to provide an update on the latest developments in early diagnosis and specific treatment of the disease and its complications, particularly with regard to respiratory organ failure. Despite advances in treatment, the rate of mortality in the intensive care unit remains approximately 30%. Therefore, early identification of potentially severe viral pneumonia is extremely important to optimize treatment in these patients. The pathogenesis of influenza virus infection depends on viral virulence and host response. Thus, in some patients, it is associated with an excessive systemic response mediated by an authentic cytokine storm. This process leads to severe primary pneumonia and acute respiratory distress syndrome. Initial prognostication in the emergency department based on comorbidities, vital signs, and biomarkers (e.g., procalcitonin, ferritin, human leukocyte antigen-DR, mid-regional proadrenomedullin, and lactate) is important. Identification of these biomarkers on admission may facilitate clinical decision-making to determine early admission to the hospital or the intensive care unit. These decisions are reached considering pathophysiological circumstances that are associated with a poor prognosis (e.g., bacterial co-infection, hyperinflammation, immune paralysis, severe endothelial damage, organ dysfunction, and septic shock). Moreover, early implementation is important to increase treatment efficacy. Based on a limited level of evidence, all current guidelines recommend using oseltamivir in this setting. The possibility of drug resistance should also be considered. Alternative options include other antiviral drugs and combination therapies with monoclonal antibodies. Importantly, it is not recommended to use corticosteroids in the initial treatment of these patients. Furthermore, the implementation of supportive measures for respiratory failure is essential. Current recommendations are limited, heterogeneous, and not regularly updated. Early intubation and mechanical ventilation is the basic treatment for patients with severe respiratory failure. Prone ventilation should be promptly performed in patients with acute respiratory distress syndrome, while early tracheostomy should be considered in case of planned prolonged mechanical ventilation. Clinical trials on antiviral treatment and respiratory support measures specifically for these patients, as well as specific recommendations for different at-risk populations, are necessary to improve outcomes.

The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the FDA are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Notably, owing to the high variability of IVs, no drug exists that can effectively treat all types and subtypes of IVs. Moreover, the current trend of drug resistance is likely to continue as the viral genome is constantly mutating. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

[Respiratory viral infections : Under special consideration of severe acute respiratory syndrome coronavirus 2 and influenza viruses]

Respiratory viruses cause the highest number of morbidities and deaths annually among all infectious pathogens. This article discusses the current epidemiology, pathogenesis, risk factors, and drug treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza viruses, respiratory syncytial virus (RSV), and other respiratory viruses. The SARS-CoV‑2 and influenza are preventable with vaccines and a first vaccine against RSV is available since 08/2023. For infections with SARS-CoV‑2 and influenza, a stage-specific (antiviral) drug treatment is also recommended. Due to the high and commonly underestimated disease burden caused by RSV, it must be hoped that antiviral substances will be found in the future. In patients at risk, particular attention should be paid to an adequate vaccination status against respiratory pathogens and if there is clinical suspicion of a viral airway infection, the pathogen should be promptly identified and, if necessary, specific treatment should be carried out. Now that effective vaccinations and antiviral drugs are available, the challenge is to use them for all patients at risk and thus really prevent avoidable infections, severe courses and long-term sequelae.

Effectiveness of intravenous peramivir for the treatment of influenza A/H3N2 and influenza B/Victoria in hospitalized children

OBJECTIVE

To optimize the medication administered to children with influenza, we evaluated the effectiveness of peramivir in hospitalized children with influenza A/H3N2 and influenza B/Victoria.

METHODS

A retrospective study was conducted from October 2019 to March 2020 in children aged 29 days to 18 years with influenza A/H3N2 or B/Victoria. A total of 97 patients were enrolled and treated with intravenous infusion of peramivir.

RESULTS

The duration of influenza virus nucleic acid positivity in the influenza A/H3N2 group (3 days) was shorter than that in the influenza B/Victoria group (4 days) (P = 0.008). The remission time of fever symptoms in the influenza A/H3N2 group was 14 h, which was significantly shorter than that in the influenza B/Victoria group (26 h) (P = 0.042). In the 6-18 years age group, the median duration of virus nucleic acid positivity for children with influenza B/Victoria (4 days) was longer than that for children with influenza A/H3N2 (2 days) (P = 0.005). The incidence of adverse drug reactions (ADRs) with peramivir in the influenza A/H3N2 group and the influenza B/Victoria group was 2.04% (n = 1/49) and 4.17% (n = 2/48), respectively (P = 0.617).

CONCLUSIONS

A difference in the effectiveness of peramivir against different subtypes of influenza was observed. Compared to those infected with influenza B/Victoria, the children infected with influenza A/H3N2 experienced a significantly shorter duration of influenza virus nucleic acid positivity and remission time of fever symptoms.

Evolution of Influenza Viruses-Drug Resistance, Treatment Options, and Prospects

Viral evolution refers to the genetic changes that a virus accumulates during its lifetime which can arise from adaptations in response to environmental changes or the immune response of the host. Influenza A virus is one of the most rapidly evolving microorganisms. Its genetic instability may lead to large changes in its biological properties, including changes in virulence, adaptation to new hosts, and even the emergence of infectious diseases with a previously unknown clinical course. Genetic variability makes it difficult to implement effective prophylactic programs, such as vaccinations, and may be responsible for resistance to antiviral drugs. The aim of the review was to describe the consequences of the variability of influenza viruses, mutations, and recombination, which allow viruses to overcome species barriers, causing epidemics and pandemics. Another consequence of influenza virus evolution is the risk of the resistance to antiviral drugs. Thus far, one class of drugs, M2 protein inhibitors, has been excluded from use because of mutations in strains isolated in many regions of the world from humans and animals. Therefore, the effectiveness of anti-influenza drugs should be continuously monitored in reference centers representing particular regions of the world as a part of epidemiological surveillance.

Discovery of Novel Boron-Containing N-Substituted Oseltamivir Derivatives as Anti-Influenza A Virus Agents for Overcoming N1-H274Y Oseltamivir-Resistant

To address drug resistance to influenza virus neuraminidase inhibitors (NAIs), a series of novel boron-containing N-substituted oseltamivir derivatives were designed and synthesized to target the 150-cavity of neuraminidase (NA). In NA inhibitory assays, it was found that most of the new compounds exhibited moderate inhibitory potency against the wild-type NAs. Among them, compound 2c bearing 4-(3-boronic acid benzyloxy)benzyl group displayed weaker or slightly improved activities against group-1 NAs (H1N1, H5N1, H5N8 and H5N1-H274Y) compared to that of oseltamivir carboxylate (OSC). Encouragingly, 2c showed 4.6 times greater activity than OSC toward H5N1-H274Y NA. Moreover, 2c exerted equivalent or more potent antiviral activities than OSC against H1N1, H5N1 and H5N8. Additionally, 2c demonstrated low cytotoxicity in vitro and no acute toxicity at the dose of 1000 mg/kg in mice. Molecular docking of 2c was employed to provide a possible explanation for the improved anti-H274Y NA activity, which may be due to the formation of key additional hydrogen bonds with surrounding amino acid residues, such as Arg152, Gln136 and Val149. Taken together, 2c appeared to be a promising lead compound for further optimization.

In Silico Studies Reveal Peramivir and Zanamivir as an Optimal Drug Treatment Even If H7N9 Avian Type Influenza Virus Acquires Further Resistance

An epidemic of avian type H7N9 influenza virus, which took place in China in 2013, was enhanced by a naturally occurring R294K mutation resistant against Oseltamivir at the catalytic site of the neuraminidase. To cope with such drug-resistant neuraminidase mutations, we applied the molecular docking technique to evaluate the fitness of the available drugs such as Oseltamivir, Zanamivir, Peramivir, Laninamivir, L-Arginine and Benserazide hydrochloride concerning the N9 enzyme with single (R294K, R119K, R372K), double (R119_294K, R119_372K, R294_372K) and triple (R119_294_372K) mutations in the pocket. We found that the drugs Peramivir and Zanamivir score best amongst the studied compounds, demonstrating their high binding potential towards the pockets with the considered mutations. Despite the fact that mutations changed the shape of the pocket and reduced the binding strength for all drugs, Peramivir was the only drug that formed interactions with the key residues at positions 119, 294 and 372 in the pocket of the triple N9 mutant, while Zanamivir demonstrated the lowest RMSD value (0.7 Å) with respect to the reference structure.

Iterative Optimization and Structure-Activity Relationship Studies of Oseltamivir Amino Derivatives as Potent and Selective Neuraminidase Inhibitors via Targeting 150-Cavity

With our continuous endeavors in seeking neuraminidase (NA) inhibitors, we reported herein three series of novel oseltamivir amino derivatives with the goal of exploring the druggable chemical space inside the 150-cavity of influenza virus NAs. Among them, around half of the compounds in series C were demonstrated to be better inhibitors against both wild-type and oseltamivir-resistant group-1 NAs than oseltamivir carboxylate (OSC). Notably, compounds 12d, 12e, 15e, and 15i showed more potent or equipotent antiviral activity against H1N1, H5N1, and H5N8 viruses compared to OSC in cellular assays. Furthermore, compounds 12e and 15e exhibited high metabolic stability in human liver microsomes (HLMs) and low inhibitory effect on main cytochrome P450 (CYP) enzymes, as well as low acute/subacute toxicity and certain antiviral efficacy in vivo. Also, pharmacokinetic (PK) and molecular docking studies were performed. Overall, 12e and 15e possess great potential to serve as anti-influenza candidates and are worthy of further investigation.

Antiviral Drugs in Influenza

Flu is a serious health, medical, and economic problem, but no therapy is yet available that has satisfactory results and reduces the occurrence of these problems. Nearly 20 years after the registration of the previous therapy, baloxavir marboxil, a drug with a new mechanism of action, recently appeared on the market. This is a promising step in the fight against the influenza virus. This article presents the possibilities of using all available antiviral drugs specific for influenza A and B. We compare all currently recommended anti-influenza medications, considering their mechanisms of action, administration, indications, target groups, effectiveness, and safety profiles. We demonstrate that baloxavir marboxil presents a similar safety and efficacy profile to those of drugs already used in the treatment of influenza. Further research on combination therapy is highly recommended and may have promising results.

Impact of the R292K Mutation on Influenza A (H7N9) Virus Resistance towards Peramivir: A Molecular Dynamics Perspective

In March 2013, a novel avian influenza A (H7N9) virus emerged in China. By March 2021, it had infected more than 1500 people, raising concerns regarding its epidemic potential. Similar to the highly pathogenic H5N1 virus, the H7N9 virus causes severe pneumonia and acute respiratory distress syndrome in most patients. Moreover, genetic analysis showed that this avian H7N9 virus carries human adaptation markers in the hemagglutinin and polymerase basic 2 (PB2) genes associated with cross-species transmissibility. Clinical studies showed that a single mutation, neuraminidase (NA) R292K (N2 numbering), induces resistance to peramivir in the highly pathogenic H7N9 influenza A viruses. Therefore, to evaluate the risk for human public health and understand the possible source of drug resistance, we assessed the impact of the NA-R292K mutation on avian H7N9 virus resistance towards peramivir using various molecular dynamics approaches. We observed that the single point mutation led to a distorted peramivir orientation in the enzyme active site which, in turn, perturbed the inhibitor's binding. The R292K mutation induced a decrease in the interaction among neighboring amino acid residues when compared to its wild-type counterpart, as shown by the high degree of fluctuations in the radius of gyration. MM/GBSA calculations revealed that the mutation caused a decrease in the drug binding affinity by 17.28 kcal/mol when compared to the that for the wild-type enzyme. The mutation caused a distortion of hydrogen bond-mediated interactions with peramivir and increased the accessibility of water molecules around the K292 mutated residue.

2021-2022 AMMI Canada guidance on the use of antiviral drugs for influenza in the COVID-19 pandemic setting in Canada

We provide an update to the Association of Medical Microbiology and Infectious Disease Canada seasonal influenza foundation guideline on the use of antiviral drugs for influenza for the upcoming 2021-2022 influenza season in Canada. Peramivir and baloxavir marboxil were licensed in Canada in 2017 and 2020, respectively, but neither is currently marketed. Thus, this guidance continues to focus on further optimizing the use of oseltamivir and zanamivir. Important issues for this year include the implications of co-circulation of severe acute respiratory syndrome coronavirus 2 and influenza viruses; the role of diagnostic testing in relation to impact on patient management; and dosing and administration recommendations for neuraminidase inhibitors for various at-risk age groups.

Discovery of New Ginsenol-Like Compounds with High Antiviral Activity

A number of framework amides with a ginsenol backbone have been synthesized using the Ritter reaction. We named the acetamide as Ginsamide. A method was developed for the synthesis of the corresponding amine and thioacetamide. The new compounds revealed a high activity against H1N1 influenza, which was confirmed using an animal model. Biological experiments were performed to determine the mechanism of action of the new agents, a ginsamide-resistant strain of influenza virus was obtained, and the pathogenicity of the resistant strain and the control strain was studied. It was shown that the emergence of resistance to Ginsamide was accompanied by a reduction in the pathogenicity of the influenza virus.

Identification of C5-NH2 Modified Oseltamivir Derivatives as Novel Influenza Neuraminidase Inhibitors with Highly Improved Antiviral Activities and Favorable Druggability

Our previous efforts have proved that modifications targeting the 150-cavity of influenza neuraminidase can achieve more potent and more selective inhibitors. In this work, four subseries of C5-NH₂ modified oseltamivir derivatives were designed and synthesized to explore every region inside the 150-cavity. Among them, compound 23d was exceptionally potent against the whole panel of Group-1 NAs with IC₅₀ values ranging from 0.26 to 0.73 nM, being 15-53 times better than oseltamivir carboxylate (OSC) and 7-11 times better than zanamivir. In cellular assays, 23d showed more potent or equipotent antiviral activities against corresponding virus strains compared to OSC with no cytotoxicity. Furthermore, 23d exhibited high metabolic stability in human liver microsomes (HLM) and low inhibitory effect on main cytochrome P450 enzymes. Notably, 23d displayed favorable druggability in vivo and potent antiviral efficacy in the embryonated egg model and mice model. Overall, 23d appears to be a promising candidate for the treatment of influenza virus infection.

The Anti-Viral and Anti-Inflammatory Properties of Edible Bird's Nest in Influenza and Coronavirus Infections: From Pre-Clinical to Potential Clinical Application

Edible bird's nest (BN) is a Chinese traditional medicine with innumerable health benefits, including anti-viral, anti-inflammatory, neuroprotective, and immunomodulatory effects. A small number of studies have reported the anti-viral effects of EBN against influenza infections using in vitro and in vivo models, highlighting the importance of sialic acid and thymol derivatives in their therapeutic effects. At present, studies have reported that EBN suppresses the replicated virus from exiting the host cells, reduces the viral replication, endosomal trafficking of the virus, intracellular viral autophagy process, secretion of pro-inflammatory cytokines, reorient the actin cytoskeleton of the infected cells, and increase the lysosomal degradation of viral materials. In other models of disease, EBN attenuates oxidative stress-induced cellular apoptosis, enhances proliferation and activation of B-cells and their antibody secretion. Given the sum of its therapeutic actions, EBN appears to be a candidate that is worth further exploring for its protective effects against diseases transmitted through air droplets. At present, anti-viral drugs are employed as the first-line defense against respiratory viral infections, unless vaccines are available for the specific pathogens. In patients with severe symptoms due to exacerbated cytokine secretion, anti-inflammatory agents are applied. Treatment efficacy varies across the patients, and in times of a pandemic like COVID-19, many of the drugs are still at the experimental stage. In this review, we present a comprehensive overview of anti-viral and anti-inflammatory effects of EBN, chemical constituents from various EBN preparation techniques, and drugs currently used to treat influenza and novel coronavirus infections. We also aim to review the pathogenesis of influenza A and coronavirus, and the potential of EBN in their clinical application. We also describe the current literature in human consumption of EBN, known allergenic or contaminant presence, and the focus of future direction on how these can be addressed to further improve EBN for potential clinical application.

Development of General Methods for Detection of Virus by Engineering Fluorescent Silver Nanoclusters

Viruses have caused significant damage to the world. Effective detection is required to relieve the impact of viral infections. A biomolecule can be used as a template such as deoxyribonucleic acid (DNA), peptide, or protein, for the growth of silver nanoclusters (AgNCs) and for recognizing a virus. Both the AgNCs and the recognition elements are tunable, which is promising for the analysis of new viruses. Considering that a new virus such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) urgently requires a facile sensing strategy, various virus detection strategies based on AgNCs including fluorescence enhancement, color change, quenching, and recovery are summarized. Particular emphasis is placed on the molecular analysis of viruses using DNA stabilized AgNCs (DNA-AgNCs), which detect the virus's genetic material. The more widespread applications of AgNCs for general virus detection are also discussed. Further development of these technologies may address the challenge for facile detection of SARS-CoV-2.

Medicinal chemistry strategies for discovering antivirals effective against drug-resistant viruses

During the last forty years we have witnessed impressive advances in the field of antiviral drug discovery culminating with the introduction of therapies able to stop human immunodeficiency virus (HIV) replication, or cure hepatitis C virus infections in people suffering from liver disease. However, there are important viral diseases without effective treatments, and the emergence of drug resistance threatens the efficacy of successful therapies used today. In this review, we discuss strategies to discover antiviral compounds specifically designed to combat drug resistance. Currently, efforts in this field are focused on targeted proteins (e.g. multi-target drug design strategies), but also on drug conformation (either improving drug positioning in the binding pocket or introducing conformational constraints), in the introduction or exploitation of new binding sites, or in strengthening interaction forces through the introduction of multiple hydrogen bonds, covalent binding, halogen bonds, additional van der Waals forces or multivalent binding. Among the new developments, proteolysis targeting chimeras (PROTACs) have emerged as a valid approach taking advantage of intracellular mechanisms involving protein degradation by the ubiquitin-proteasome system. Finally, several molecules targeting host factors (e.g. human dihydroorotate dehydrogenase and DEAD-box polypeptide 3) have been identified as broad-spectrum antiviral compounds. Implementation of herein described medicinal chemistry strategies are expected to contribute to the discovery of new drugs effective against current and future threats due to emerging and re-emerging viral pandemics.

Influenza Viruses: Harnessing the Crucial Role of the M2 Ion-Channel and Neuraminidase toward Inhibitor Design

As a member of the Orthomyxoviridae family of viruses, influenza viruses (IVs) are known causative agents of respiratory infection in vertebrates. They remain a major global threat responsible for the most virulent diseases and global pandemics in humans. The virulence of IVs and the consequential high morbidity and mortality of IV infections are primarily attributed to the high mutation rates in the IVs' genome coupled with the numerous genomic segments, which give rise to antiviral resistant and vaccine evading strains. Current therapeutic options include vaccines and small molecule inhibitors, which therapeutically target various catalytic processes in IVs. However, the periodic emergence of new IV strains necessitates the continuous development of novel anti-influenza therapeutic options. The crux of this review highlights the recent studies on the biology of influenza viruses, focusing on the structure, function, and mechanism of action of the M2 channel and neuraminidase as therapeutic targets. We further provide an update on the development of new M2 channel and neuraminidase inhibitors as an alternative to existing anti-influenza therapy. We conclude by highlighting therapeutic strategies that could be explored further towards the design of novel anti-influenza inhibitors with the ability to inhibit resistant strains.

2020-2021 AMMI Canada guidance on the use of antiviral drugs for influenza in the setting of co-circulation of seasonal influenza and SARS-CoV-2 viruses in Canada

We provide an update to the Association of Medical Microbiology and Infectious Disease Canada foundation guidance for the upcoming 2020-2021 influenza season in Canada. Important issues for this year include the implications of co-circulation of SARS-CoV-2, the role of diagnostic testing, and a restatement of dosing and administration recommendations for neuraminidase inhibitors in various age groups and underlying health conditions. Although peramivir and baloxivir are now licensed in Canada, neither is currently marketed, so this guidance focuses on further optimizing the use of oseltamivir and zanamivir.

Pharmacokinetic behavior of peramivir in the plasma and lungs of rats after trans-nasal aerosol inhalation and intravenous injection

Peramivir, a neuraminidase inhibitor, was approved globally and is indicated for the treatment of uncomplicated influenza in adults and children. However, the only approved intravenous formulation of peramivir limits its clinical application due to the need for the specialized dosing techniques and increases the risk of contracting influenza virus infection among healthcare professionals when dosing within a short distance to the patient. The purpose of this study was to investigate the pharmacokinetic profile of peramivir in plasma and the lung of rats and to compare the profiles following administration through trans-nasal aerosol inhalation (0.0888, 0.1776, and 0.3552 mg/kg) and intravenous injection (30 mg/kg). The plasma concentration reached the C_max within 1.0 h (upon inhalation) and decreased at a t_1/2 of 6.71 and 10.9 h after inhalation and injection, respectively. The absolute bioavailability of peramivir after inhalation was 78.2 %. Overall, the pharmacokinetic exposure of peramivir in the lungs was higher than that in the plasma after aerosol inhalation. After inhalation, the C_max of peramivir in the lung was achieved within 1.0 h, and the elimination of the drug was slower than in the case of intravenous injection with t_1/2 values 1.81 h for injection and 5.72, 53.5, and 32.1 h for low, middle, and high doses administered through inhalation. The C_max and AUC_0-t values for peramivir in the lungs increased linearly with the increased inhalation dose. The results elucidate the pharmacokinetic process of peramivir after trans-nasal aerosol inhalation to rats and provide useful information for further rational application of this drug formulation.

Redox control in the pathophysiology of influenza virus infection

Triggered in response to external and internal ligands in cells and animals, redox homeostasis is transmitted via signal molecules involved in defense redox mechanisms through networks of cell proliferation, differentiation, intracellular detoxification, bacterial infection, and immune reactions. Cellular oxidation is not necessarily harmful per se, but its effects depend on the balance between the peroxidation and antioxidation cascades, which can vary according to the stimulus and serve to maintain oxygen homeostasis. The reactive oxygen species (ROS) that are generated during influenza virus (IV) infection have critical effects on both the virus and host cells. In this review, we outline the link between viral infection and redox control using IV infection as an example. We discuss the current state of knowledge on the molecular relationship between cellular oxidation mediated by ROS accumulation and the diversity of IV infection. We also summarize the potential anti-IV agents available currently that act by targeting redox biology/pathophysiology.

A Meta-Analysis Comparing the Efficacy and Safety of Peramivir with Other Neuraminidase Inhibitors for Influenza Treatment

Background and Objectives: This meta-analysis compared the efficacy and safety of peramivir compared to other neuraminidase inhibitors (NAIs). Materials and Methods: Data from PubMed, Embase, and Cochrane databases and ClinicalTrials.gov were searched until January 2019. Randomized controlled trials (RCTs) and observational studies (OSs) comparing peramivir with other NAIs for treating influenza were included. The Grading of Recommendations, Assessments, Development, and Evaluations (GRADE) system was used to judge the overall certainty of evidence; the result was moderate. The primary outcome was time to alleviation of symptoms. Twelve articles involving 2681 patients were included in this meta-analysis. We used a random-effect model to pool the effect size, which is expressed as the difference in means (MD), risk ratio (RR), and 95% confidence interval (CI). Results: Overall, peramivir was superior to other NAIs (MD = −11.214 hours, 95% CI: −19.119 to −3.310). The incidence of adverse events (RR = 1.023, 95% CI: 0.717 to 1.460) and serious adverse events (RR = 1.068, 95% CI: 0.702 to 1.625) in the peramivir group was similar to those in the oseltamivir group. In addition, peramivir had higher efficacy than each NAI alone. Conclusion: In conclusion, the efficacy of peramivir might be higher than that of other NAIs, and this agent is tolerated as well as other NAIs.

Curative efficacy and safety of peramivir in the treatment of children suspected with influenza

The data from a total of 200 children with suspected influenza virus infection were assessed at the febrile clinic of Women and Children’s hospital in Ganzhou of Jiangxi province from January 2018 to March 2019, and the patients were belonged to two groups (peramivir treatment group and oseltamivir treatment group). At the same time, 100 patients without special treatment were evaluated as the control group. We observed the patients’ fever relief time, pharyngeal pain relief time, nasal congestion relief time, runny nose symptoms relief time, days of hospitalization, days of medication, cost of medication, and adverse reactions in the three groups. We analyzed and compared the efficacy and adverse reactions of peramivir and oseltamivir in the treatment of children suspected with influenza. The recovery of body temperature, relief of cough, days of medication, and hospitalization period in the peramivir group were significantly shorter compared to the oseltamivir and control groups. The mean times to alleviation of fever in the three groups were 18.28 ± 17.74 h (peramivir group), 48.20 ± 34.28 h (oseltamivir group), and 72.56 ± 25.78 h (control group). The mean times to alleviation of cough in the three groups were 49.77 ± 27.58 h (peramivir group), 68.53 ± 32.54 h (oseltamivir group), and 59.38 ± 31.26 (control group). The cost of the peramivir group was significantly higher than that of the oseltamivir and control groups. The incidence of drug reactions in the peramivir group was significantly lower than that in the oseltamivir group. The rate of antibiotic usage in the peramivir group was significantly lower than that in the oseltamivir and control groups. Peramivir can significantly alleviate symptoms and reduce the use of antibiotics in children with suspected influenza. Peramivir has demonstrated good efficacy, high safety, and good compliance in treating children with suspected influenza infection.

Temperature Sensitive Mutations in Influenza A Viral Ribonucleoprotein Complex Responsible for the Attenuation of the Live Attenuated Influenza Vaccine

Live attenuated influenza vaccines (LAIV) have prevented morbidity and mortality associated with influenza viral infections for many years and represent the best therapeutic option to protect against influenza viral infections in humans. However, the development of LAIV has traditionally relied on empirical methods, such as the adaptation of viruses to replicate at low temperatures. These approaches require an extensive investment of time and resources before identifying potential vaccine candidates that can be safely implemented as LAIV to protect humans. In addition, the mechanism of attenuation of these vaccines is poorly understood in some cases. Importantly, LAIV are more efficacious than inactivated vaccines because their ability to mount efficient innate and adaptive humoral and cellular immune responses. Therefore, the design of potential LAIV based on known properties of viral proteins appears to be a highly appropriate option for the treatment of influenza viral infections. For that, the viral RNA synthesis machinery has been a research focus to identify key amino acid substitutions that can lead to viral attenuation and their use in safe, immunogenic, and protective LAIV. In this review, we discuss the potential to manipulate the influenza viral RNA-dependent RNA polymerase (RdRp) complex to generate attenuated forms of the virus that can be used as LAIV for the treatment of influenza viral infections, one of the current and most effective prophylactic options for the control of influenza in humans.