Current and future antiviral therapy of severe seasonal and avian influenza

Hussein S, Abdalhabib EK, Nabi SU. The critical impacts of cytokine storms in respiratory disorders

Cytokine storm (CS) refers to the spontaneous dysregulated and hyper-activated inflammatory reaction occurring in various clinical conditions, ranging from microbial infection to end-stage organ failure. Recently the novel coronavirus involved in COVID-19 (Coronavirus disease-19) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) has been associated with the pathological phenomenon of CS in critically ill patients. Furthermore, critically ill patients suffering from CS are likely to have a grave prognosis and a higher case fatality rate. Pathologically CS is manifested as hyper-immune activation and is clinically manifested as multiple organ failure. An in-depth understanding of the etiology of CS will enable the discovery of not just disease risk factors of CS but also therapeutic approaches to modulate the immune response and improve outcomes in patients with respiratory diseases having CS in the pathogenic pathway. Owing to the grave consequences of CS in various diseases, this phenomenon has attracted the attention of researchers and clinicians throughout the globe. So in the present manuscript, we have attempted to discuss CS and its ramifications in COVID-19 and other respiratory diseases, as well as prospective treatment approaches and biomarkers of the cytokine storm. Furthermore, we have attempted to provide in-depth insight into CS from both a prophylactic and therapeutic point of view. In addition, we have included recent findings of CS in respiratory diseases reported from different parts of the world, which are based on expert opinion, clinical case-control research, experimental research, and a case-controlled cohort approach.

Isolation and identification of active components from Grifola frondosa and its anti-EV71 virus effect

BACKGROUND

It is reported that anti-enterovirus 71 (EV71) drugs have some side effects on human health. Notably, fungi plays a crucial role in promoting human health and anti-virus. Grifola frondosa is a type of large medicinal and edible fungi, rich in active substances. The present study aimed to investigate the anti-EV71 effect of G. frondosa and the potential active substances.

RESULTS

In the present study, the water extract of G. frondosa was subjected to ethanol precipitation to obtain the water-extracted supernatant of G. frondosa (GFWS) and water-extracted precipitation of G. frondosa. Their inhibitory effects on EV71 virus were studied based on a cell model. The results showed that GFWS had stronger security and anti-EV71 effects. In addition, the chemical constituents of GFWS were identified by ultra-high performance liquid chromatography-tandem mass spectrometry, which were selected for further separation and purification. Three compounds, N-butylaniline, succinic acid and l-tryptophan, were isolated from GFWS by NMR spectroscopy. It is noteworthy that N-butylaniline and l-tryptophan were isolated and identified from the G. frondosa fruiting bodies for the first time. Our study found that l-tryptophan has anti-EV71 virus activity, which reduced EV71-induced apoptosis and significantly inhibited the replication process after virus adsorption. Furthermore, it could also bind to capsid protein VP1 to prevent the virus from attaching to the cells.

CONCLUSION

l-tryptophan was an inhibitor of the EV71 virus, which could be used in infant nutrition and possibly provide a new drug to treat hand, foot and mouth disease. © 2024 Society of Chemical Industry.

Insights from Avian Influenza: A Review of Its Multifaceted Nature and Future Pandemic Preparedness

Avian influenza viruses (AIVs) have posed a significant pandemic threat since their discovery. This review mainly focuses on the epidemiology, virology, pathogenesis, and treatments of avian influenza viruses. We delve into the global spread, past pandemics, clinical symptoms, severity, and immune response related to AIVs. The review also discusses various control measures, including antiviral drugs, vaccines, and potential future directions in influenza treatment and prevention. Lastly, by summarizing the insights from previous pandemic control, this review aims to direct effective strategies for managing future influenza pandemics.

Anti-Influenza Activity of Cetraria islandica Lichen Extracts in In Vitro Experiments

The toxicity and antiviral activity of extracts obtained by the methods of aqueous and ethanol extraction of bioactive substances from Cetraria islandica lichen as a raw material were studied. Aqueous and ethanol extracts of lichen were characterized by low toxicity with respect to the passaged MDCK cell culture and exhibited antiviral activity. The ethanol extract showed more potent in vitro antiviral activity against human A/H3N2 and avian A/H5N1 influenza viruses: in a concentration of 50 μg/ml, it suppressed replication of these viruses by 3.5 and 4 log₁₀, respectively, while the aqueous extract inhibited replication of viruses by 2 and 6 log₁₀, respectively, when taken in a concentration of 500 μg/ml that was 10-fold higher than the concentration of the ethanol extract.

Structural basis for a human broadly neutralizing influenza A hemagglutinin stem-specific antibody including H17/18 subtypes

Influenza infection continues are a persistent threat to public health. The identification and characterization of human broadly neutralizing antibodies can facilitate the development of antibody drugs and the design of universal influenza vaccines. Here, we present structural information for the human antibody PN-SIA28's heterosubtypic binding of hemagglutinin (HA) from circulating and emerging potential influenza A viruses (IAVs). Aside from group 1 and 2 conventional IAV HAs, PN-SIA28 also inhibits membrane fusion mediated by bat-origin H17 and H18 HAs. Crystallographic analyses of Fab alone or in complex with H1, H14, and H18 HA proteins reveal that PN-SIA28 binds to a highly conserved epitope in the fusion domain of different HAs, with the same CDRHs but different CDRLs for different HAs tested, distinguishing it from other structurally characterized anti-stem antibodies. The binding characteristics of PN-SIA28 provides information to support the design of increasingly potent engineered antibodies, antiviral drugs, and/or universal influenza vaccines.

Repurposing of Chemotherapeutics to Combat COVID-19

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is a novel strain of SARS coronavirus. The COVID-19 disease caused by this virus was declared a pandemic by the World Health Organization (WHO). SARS-CoV-2 mainly spreads through droplets sprayed by coughs or sneezes of the infected to a healthy person within the vicinity of 6 feet. It also spreads through asymptomatic carriers and has negative impact on the global economy, security and lives of people since 2019. Numerous lives have been lost to this viral infection; hence there is an emergency to build up a potent measure to combat SARS-CoV-2. In view of the non-availability of any drugs or vaccines at the time of its eruption, the existing antivirals, antibacterials, antimalarials, mucolytic agents and antipyretic paracetamol were used to treat the COVID-19 patients. Still there are no specific small molecule chemotherapeutics available to combat COVID-19 except for a few vaccines approved for emergency use only. Thus, the repurposing of chemotherapeutics with the potential to treat COVID-19 infected people is being used. The antiviral activity for COVID-19 and biochemical mechanisms of the repurposed drugs are being explored by the biological assay screening and structure-based in silico docking simulations. The present study describes the various US-FDA approved chemotherapeutics repositioned to combat COVID-19 along with their screening for biological activity, pharmacokinetic and pharmacodynamic evaluation.

Anti-Influenza Virus Potential of Probiotic Strain Lactoplantibacillus plantarum YML015 Isolated from Korean Fermented Vegetable

Lactic acid bacteria are one of the potential natural remedies used worldwide, commonly known as probiotics. Here, the aim of this research investigation was to isolate a probiotic Lactobacilli strain, YLM015, from the popular Korean fermented vegetable “Kimchi” and to evaluate its anti-viral potential against influenza virus A (IFVA) H1N1 using the MDCK cell line in vitro, and in embryonated eggs in ovo. The YML015 strain was selected from among the 1200 Lactobacilli isolates for further studies based on its potent anti-viral efficacy. YML015 was identified and characterized as Lactoplantibacillus plantarum YML015 based on the 16S rRNA gene sequencing and biochemically with an API 50 CHL Kit. In ovo assay experienced with embryonated eggs and the hemagglutination inhibition method, as well as cytopathogenic reduction assay, was performed individually to observe anti-influenza viral activity of YML015 against influenza virus A H1N1. Additionally, YML015 was classified for its non-resistance nature as safe for humans and animals as confirmed by the antibiotic susceptibility (MIC) test, cell viability, and hemolysis assay. The heat stability test was also experienced by using different heat-treated cell-free supernatant (CFS) samples of YML015. As a result, YML015 showed highly potent anti-viral activity against influenza virus A H1N1 in vitro in the MDCK cell line. Overall findings suggest that anti-influenza viral activity of L. plantarum YML015 makes it a potential candidate of choice for use as an influential probiotic in pharmacological preparations to protect humans and animals from flu and viral infection.

Modulating cholesterol-rich lipid rafts to disrupt influenza A virus infection

Influenza A virus (IAV) is widely disseminated across different species and can cause recurrent epidemics and severe pandemics in humans. During infection, IAV attaches to receptors that are predominantly located in cell membrane regions known as lipid rafts, which are highly enriched in cholesterol and sphingolipids. Following IAV entry into the host cell, uncoating, transcription, and replication of the viral genome occur, after which newly synthesized viral proteins and genomes are delivered to lipid rafts for assembly prior to viral budding from the cell. Moreover, during budding, IAV acquires an envelope with embedded cholesterol from the host cell membrane, and it is known that decreased cholesterol levels on IAV virions reduce infectivity. Statins are commonly used to inhibit cholesterol synthesis for preventing cardiovascular diseases, and several studies have investigated whether such inhibition can block IAV infection and propagation, as well as modulate the host immune response to IAV. Taken together, current research suggests that there may be a role for statins in countering IAV infections and modulating the host immune response to prevent or mitigate cytokine storms, and further investigation into this is warranted.

Potential Antiviral Activity of Lactiplantibacillus plantarum KAU007 against Influenza Virus H1N1

The development of antiviral resistance has exacerbated a growing threat to public health. As a result, there is increasing demand for unconventional antivirals that can effectively replace the presently in-use drugs. Lactic acid-producing bacteria (LAB) are among the most common bacteria used in the food industry. These bacteria play an essential role in the fermentation of many foods and feed. Additionally, these bacteria are considered more economical, efficient, and safe “nutraceuticals” in the health care arsenal. Therefore, we carried out the screening and molecular characterization of raw camel milk LAB isolates and tested their inhibitory activity against influenza virus H1N1. The strain that exhibited the highest antiviral activity against the H1N1 virus, confirmed by hemagglutination assay, was identified as Lactiplantibacillus plantarum KAU007. The study also confirmed the non-cytotoxic behavior of CFCS isolated from KAU007 against MDCK cells, approving its safety concern against the mammalian cells. Besides, CFCS at 5 and 10 mg/mL significantly decreased the level of IFN-γ (p < 0.001 and p < 0.001) and IL-6 (p < 0.001 and p < 0.005) in a dose-dependent manner, respectively. This is a preliminary report about the anti-influenza activity of KAU007 isolated from camel milk. This study reinforces that camel milk contains beneficial LAB isolates with antagonistic properties against the H1N1 influenza virus.

Development and validation of a quantitative method for 15 antiviral drugs in poultry muscle using liquid chromatography coupled to tandem mass spectrometry

The objective of this work was to develop a quantitative multi-residue method for analysing antiviral drug residues and their metabolites in poultry meat samples. Antiviral drugs are not licensed for the treatment of influenza in food producing animals. However, there have been some reports indicating their illegal use in poultry. In this study, a method was developed for the analysis of 15 antiviral drug residues in poultry muscle (chicken, duck, quail and turkey) using liquid chromatography coupled to tandem mass spectrometry. This included 13 drugs against influenza and associated metabolites, but also two drugs employed for the treatment of herpes (acyclovir and ganciclovir). The method required the development of a novel chromatographic separation using a hydrophilic interaction chromatographic (HILIC) BEH amide column, which was necessary to retain the highly polar compounds. The analytes were detected using a triple quadrupole mass spectrometer operating in positive electrospray ionization mode. A range of different sample preparation protocols suitable for polar compounds were evaluated. The most effective procedure was based on a simple acetonitrile-based protein precipitation step followed by a further dilution in a methanol/water solution. The confirmatory method was validated according to the EU 2021/808 guidelines on different species including chicken, duck, turkey and quail. The validation was performed using various calibration curves ranging from 0.1 µg kg^-1to 200 µg kg^-1, according to the analyte. Depending on the analyte sensitivity, decision limits achieved ranged from 0.12 µg kg^-1 for arbidol to 34.7 µg kg^-1 for ribavirin. Overall, the reproducibility precision values ranged from 2.8% to 22.7% and the recoveries from 84% to 127%. The method was applied to 120 commercial poultry samples from the Irish market, which were all found to be residue-free.

The Antiviral Potential of Probiotics—A Review on Scientific Outcomes

A rich repertoire of research studies on probiotics has been documented as one of the therapeutic agents or adjuvants for vaccines in treating viral infections. It is well known that the immunomodulatory properties of probiotics reduce the severity of viral infections. The efficacy of probiotics alone and combined boost up the host’s innate immunity, thereby developing a robust antiviral paradigm. As dietary and therapeutic measures, probiotics potentially work as an alternative for those who lack access to vaccines or antiviral drugs. Potential probiotic mechanisms include competing with pathogens for nutrients and colonization sites, producing antimicrobial metabolites and enhancing protective immune responses. The live probiotics can reach and colonize the host animals’ intestines then confer the health benefits by improving the host’s natural defence against viral infections. The research studies on probiotics suggest that they reduce the risk of viral infections, yet the innermost mechanisms are still unknown. The reason for scripting this review is to discuss the current developments in probiotic therapeutic measures and their probable insights into antiviral agents.

Optimization and SAR research at the piperazine and phenyl rings of JNJ4796 as new anti-influenza A virus agents, part 1

JNJ4796, a small molecule fuse inhibitor targeting the conserved stem region of hemagglutinin, effectively neutralized a broad spectrum of group 1 influenza A virus (IAV), and protected mice against lethal and sublethal influenza challenge after oral administration. In this study, we reported the modification and structure-activity relationship (SAR) of C (piperazine ring) and E (phenyl ring) rings of JNJ4796. Compound (R)-2c was identified to show excellent in vitro activity against IAV H1N1 and Oseltamivir-resistant IAV H1N1 stains (IC₅₀: 0.03-0.06 μM), low cytotoxicity (CC₅₀ > 200 μM), accepted oral PK profiles and low inhibition rate of hERG (13.2%, at 10 μM). Evaluation for the in vivo anti-IAV efficacy of (R)-2c will begin soon.

Influenza Therapeutics in Clinical Practice-Challenges and Recent Advances

In the last few years, several new direct-acting influenza antivirals have been licensed, and others have advanced in clinical development. The increasing diversity of antiviral classes should allow an adequate public health response should a resistant virus to one agent or class widely circulate. One new antiviral, baloxavir marboxil, has been approved in the United States for treatment of influenza in those at high risk of developing influenza-related complications. Except for intravenous zanamivir in European Union countries, no antivirals have been licensed specifically for the indication of severe influenza or hospitalized influenza. This review addresses recent clinical developments involving selected polymerase inhibitors, neuraminidase inhibitors, antibody-based therapeutics, and host-directed therapies. There are many knowledge gaps for most of these agents because some data are not published and multiple pivotal studies are in progress at present. This review also considers important clinical research issues, including regulatory pathways, study designs, endpoints, and target populations encountered during the clinical development of novel therapeutics.

Sugiol, a diterpenoid: Therapeutic actions and molecular pathways involved

Understanding how the natural products structural diversity interacts with cellular metabolism and infectious disease targets remains a challenge. Inflammation is an important process in the human healing response in which the tissues respond to injuries induced by many agents, including pathogens. In recent years, several drugs derived from plant products have been developed, and current drug research is actively investigating the pharmacotherapeutic role of natural products in advanced multimodal inflammatory disease targeting. Sugiol, a diterpenoid, can act as an antimicrobial, antioxidant, anti-inflammatory, anti-carcinoma, antiviral, and cardiovascular agent. Until now, there have been no updates on the pharmacotherapeutic advancement of sugiol. Herein, we correlate the diverse molecular pathways in disease prevention involving sugiol. We also discuss the origins of its structural diversity and summarize new research directions toward exploring its novel effective future uses. Despite much evidence of its efficacy and safety, the sugiol has not yet been approved as a therapeutic agent due to its low bioavailability, and insolubility in an aqueous environment. The aim of this review is to renew and update noteworthy information on the pharmacotherapeutic characteristics of sugiol to approach different advanced strategies employed in the context of natural nurturing-based biomedicine.

Development of High Dose Oseltamivir Phosphate Dry Powder for Inhalation Therapy in Viral Pneumonia

Oseltamivir phosphate (OP) is an antiviral drug available only as oral therapy for the treatment of influenza and as a potential treatment option when in combination with other medication in the fight against the corona virus disease (COVID-19) pneumonia. In this study, OP was formulated as a dry powder for inhalation, which allows drug targeting to the site of action and potentially reduces the dose, aiming a more efficient therapy. Binary formulations were based on micronized excipient particles acting like diluents, which were blended with the drug OP. Different excipient types, excipient ratios, and excipient size distributions were prepared and examined. To investigate the feasibility of delivering high doses of OP in a single dose, 1:1, 1:3, and 3:1 drug/diluent blending ratios have been prepared. Subsequently, the aerosolization performance was evaluated for all prepared formulations by cascade impaction using a novel medium-resistance capsule-based inhaler (UNI-Haler). Formulations with micronized trehalose showed relatively excellent aerosolization performance with highest fine-particle doses in comparison to examined lactose, mannitol, and glucose under similar conditions. Focusing on the trehalose-based dry-powder inhalers' (DPIs) formulations, a physicochemical characterization of extra micronized grade trehalose in relation to the achieved performance in dispersing OP was performed. Additionally, an early indication of inhaled OP safety on lung cells was noted by the viability MTT assay utilizing Calu-3 cells.

An influenza A hemagglutinin small-molecule fusion inhibitor identified by a new high-throughput fluorescence polarization screen

Influenza hemagglutinin (HA) glycoprotein is the primary surface antigen targeted by the host immune response and a focus for development of novel vaccines, broadly neutralizing antibodies (bnAbs), and therapeutics. HA enables viral entry into host cells via receptor binding and membrane fusion and is a validated target for drug discovery. However, to date, only a very few bona fide small molecules have been reported against the HA. To identity new antiviral lead candidates against the highly conserved fusion machinery in the HA stem, we synthesized a fluorescence-polarization probe based on a recently described neutralizing cyclic peptide P7 derived from the complementarity-determining region loops of human bnAbs FI6v3 and CR9114 against the HA stem. We then designed a robust binding assay compatible with high-throughput screening to identify molecules with low micromolar to nanomolar affinity to influenza A group 1 HAs. Our simple, low-cost, and efficient in vitro assay was used to screen H1/Puerto Rico/8/1934 (H1/PR8) HA trimer against ∼72,000 compounds. The crystal structure of H1/PR8 HA in complex with our best hit compound F0045(S) confirmed that it binds to pockets in the HA stem similar to bnAbs FI6v3 and CR9114, cyclic peptide P7, and small-molecule inhibitor JNJ4796. F0045 is enantioselective against a panel of group 1 HAs and F0045(S) exhibits in vitro neutralization activity against multiple H1N1 and H5N1 strains. Our assay, compound characterization, and small-molecule candidate should further stimulate the discovery and development of new compounds with unique chemical scaffolds and enhanced influenza antiviral capabilities.

Quantum leap of monoclonal antibody (mAb) discovery and development in the COVID-19 era

In recent years the global market for monoclonal antibodies (mAbs) became a multi-billion-dollar business. This success is mainly driven by treatments in the oncology and autoimmune space. Instead, development of effective mAbs against infectious diseases has been lagging behind. For years the high production cost and limited efficacy have blocked broader application of mAbs in the infectious disease space, which instead has been dominated for almost a century by effective and cheap antibiotics and vaccines. Only very few mAbs against RSV, anthrax, Clostridium difficile or rabies have reached the market. This is about to change. The development of urgently needed and highly effective mAbs as preventive and therapeutic treatments against a variety of pathogens is gaining traction. Vast advances in mAb isolation, engineering and production have entirely shifted the cost-efficacy balance. MAbs against devastating diseases like Ebola, HIV and other complex pathogens are now within reach. This trend is further accelerated by ongoing or imminent health crises like COVID-19 and antimicrobial resistance (AMR), where antibodies could be the last resort. In this review we will retrace the history of antibodies from the times of serum therapy to modern mAbs and lay out how the current run for effective treatments against COVID-19 will lead to a quantum leap in scientific, technological and health care system innovation around mAb treatments for infectious diseases.

Investigation of Binding Affinity between Potential Antiviral Agents and PB2 Protein of Influenza A: Non-equilibrium Molecular Dynamics Simulation Approach

The PB2 protein of the influenza virus RNA polymerase is a major virulence determinant of influenza viruses. It binds to the cap structure at the 5' end of host mRNA to generate short capped RNA fragments that are used as primers for viral transcription named cap-snatching. A large number of the compounds were shown to bind the minimal cap-binding domain of PB2 to inhibit the cap-snatching machinery. However, their binding in the context of an extended form of the PB2 protein has remained elusive. A previous study reported some promising compounds including azaindole and hydroxymethyl azaindole, which were analyzed here to predict binding affinity to PB2 protein using the steered molecular dynamics (SMD) and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) methods. The results show that the rupture force (F_max) value of three complexes is in agreement with the binding free energy value (ΔG_bind) estimated by the MM-PBSA method, whereas for the non-equilibrium pulling work (W_pull) value a small difference between A_PB2-4 and A_PB2-12 was observed. The binding affinity results indicate the A_PB2-12 complex is more favorable than the A_PB2-4 and A_PB2-16 complexes, which means the inhibitor (12) has the potential to be further developed as anti-influenza agents in the treatment of influenza A.

Baicalin inhibits influenza virus A replication via activation of type I IFN signaling by reducing miR‑146a

Influenza virus A (IVA) is one of the predominant causative agents of the seasonal flu and has become an important cause of morbidity worldwide. Great efforts have been paid to develop vaccines against IVA. However, due to antigenic drift in influenza virus A and rapid emergence of drug-resistant strains, current available vaccines or anti-IVA chemotherapeutics are consistently inefficient. Hence, various more broadly effective drugs have become important for the prevention and treatment of IVA. Of these drugs, baicalin, a flavonoid isolated from Radix Scutellaria, is a promising example. However, little is known in regards to its pharmacological mechanism. Here, it was demonstrated that baicalin inhibits the H1N1 and H3N2 viruses in A549 cells. Subsequently, it was found that miR-146a was markedly downregulated by treatment of baicalin. Additionally, further experiments revealed that miR-146a was able to promote the replication of H1N1 and H3N2 by targeting TNF receptor-associated factor 6 (TRAF6), a pivotal adaptor in the interferon (IFN) production signaling pathway, to downregulate type I IFN production, and enrichment of miR-146a eliminated the anti-IVA effects of baicalin on the H1N1 and H3N2 viruses. Additionally, in vivo experiments demonstrated that baicalin could protect mice during H1N1 infection. Taken together, our findings firstly illustrated the anti-IVA molecular mechanism of baicalin and provide new evidence for targeting miRNAs to prevent and treat viral infection, such as the H1N1 and H3N2 viruses.

In Vivo Imaging-Driven Approaches to Study Virus Dissemination and Pathogenesis

Viruses are causative agents for many diseases and infect all living organisms on the planet. Development of effective therapies has relied on our ability to isolate and culture viruses in vitro, allowing mechanistic studies and strategic interventions. While this reductionist approach is necessary, testing the relevance of in vitro findings often takes a very long time. New developments in imaging technologies are transforming our experimental approach where viral pathogenesis can be studied in vivo at multiple spatial and temporal resolutions. Here, we outline a vision of a top-down approach using noninvasive whole-body imaging as a guide for in-depth characterization of key tissues, physiologically relevant cell types, and pathways of spread to elucidate mechanisms of virus spread and pathogenesis. Tool development toward imaging of infectious diseases is expected to transform clinical diagnosis and treatment.

A Novel Fluorescent and Bioluminescent Bireporter Influenza A Virus To Evaluate Viral Infections

Studying influenza A virus (IAV) requires the use of secondary approaches to detect the presence of virus in infected cells. To overcome this problem, we and others have generated recombinant IAV expressing fluorescent or luciferase reporter genes. These foreign reporter genes can be used as valid surrogates to track the presence of virus. However, the limited capacity for incorporating foreign sequences in the viral genome forced researchers to select a fluorescent or a luciferase reporter gene, depending on the type of study. To circumvent this limitation, we engineered a novel recombinant replication-competent bireporter IAV (BIRFLU) expressing both fluorescent and luciferase reporter genes. In cultured cells, BIRFLU displayed growth kinetics comparable to those of wild-type (WT) virus and was used to screen neutralizing antibodies or compounds with antiviral activity. The expression of two reporter genes allows monitoring of viral inhibition by fluorescence or bioluminescence, overcoming the limitations associated with the use of one reporter gene as a readout. In vivo, BIRFLU effectively infected mice, and both reporter genes were detected using in vivo imaging systems (IVIS). The ability to generate recombinant IAV harboring multiple foreign genes opens unique possibilities for studying virus-host interactions and for using IAV in high-throughput screenings (HTS) to identify novel antivirals that can be incorporated into the therapeutic armamentarium to control IAV infections. Moreover, the ability to genetically manipulate the viral genome to express two foreign genes offers the possibility of developing novel influenza vaccines and the feasibility for using recombinant IAV as vaccine vectors to treat other pathogen infections.IMPORTANCE Influenza A virus (IAV) causes a human respiratory disease that is associated with significant health and economic consequences. In recent years, the use of replication-competent IAV expressing an easily traceable fluorescent or luciferase reporter protein has significantly contributed to progress in influenza research. However, researchers have been forced to select a fluorescent or a luciferase reporter gene due to the restricted capacity of the influenza viral genome for including foreign sequences. To overcome this limitation, we generated, for the first time, a recombinant replication-competent bireporter IAV (BIRFLU) that stably expresses two reporter genes (one fluorescent and one luciferase) to track IAV infections in vitro and in vivo The combination of cutting-edge techniques from molecular biology, animal research, and imaging technologies brings researchers the unique opportunity to use this new generation of reporter-expressing IAV to study viral infection dynamics in both cultured cells and animal models of viral infection.

Anti-H7N9 avian influenza A virus activity of interferon in pseudostratified human airway epithelium cell cultures

BACKGROUND

Since H7N9 influenza A virus (H7N9) was first reported in 2013, five waves of outbreaks have occurred, posing a huge threat to human health. In preparation for a potential H7N9 epidemic, it is essential to evaluate the efficacy of anti-H7N9 drugs with an appropriate model.

METHODS

Well-differentiated pseudostratified human airway epithelium (HAE) cells were grown at the air-liquid interface, and the H7N9 cell tropism and cytopathic effect were detected by immunostaining and hematoxylin-eosin (HE) staining. The H7N9 replication kinetics and anti-H7N9 effect of recombinant human α2b (rhIFN-α2b) and rhIFN-λ1 were compared with different cell lines. The H7N9 viral load and interferon-stimulated gene (ISG) expression were quantified by real-time PCR assays.

RESULTS

H7N9 could infect both ciliated and non-ciliated cells within the three-dimensional (3D) HAE cell culture, which reduced the number of cilia and damaged the airways. The H7N9 replication kinetics differed between traditional cells and 3D HAE cells. Interferon had antiviral activity against H7N9 and alleviated epithelial cell lesions; the antiviral activity of rhIFN-α2b was slightly better than that of rhIFN-λ1. In normal cells, rhIFN-α2b induced a greater amount of ISG expression (MX1, OAS1, IFITM3, and ISG15) compared with rhIFN-λ1, but in 3D HAE cells, this trend was reversed.

CONCLUSIONS

Both rhIFN-α2b and rhIFN-λ1 had antiviral activity against H7N9, and this protection was related to the induction of ISGs. The 3D cell culture model is suitable for evaluating interferon antiviral activity because it can demonstrate realistic in vivo-like effects.

Second-order asymmetric transformation and its application for the practical synthesis of α-amino acids

We report a discovery of a new rimantadine [1-(1-adamantyl)ethanamine]-derived chiral ligand and its application for the preparation of α-amino acids using the second-order asymmetric transformation approach. The operational ease of experimental procedures coupled with excellent chemical yields and stereochemical outcome suggests some potential synthetic generality of this approach.

Computational Prediction of the Epitopes of HA1 Protein of Influenza Viruses to its Neutralizing Antibodies

In this work, we have used a new method to predict the epitopes of HA1 protein of influenza virus to several antibodies HC19, CR9114, BH151 and 4F5. While our results reproduced the binding epitopes of H3N2 or H5N1 for the neutralizing antibodies HC19, CR9114, and BH151 as revealed from the available crystal structures, additional epitopes for these antibodies were also suggested. Moreover, the predicted epitopes of H5N1 HA1 for the newly developed antibody 4F5 are located at the receptor binding domain, while previous study identified a region 76-WLLGNP-81 as the epitope. The possibility of antibody recognition of influenza virus via different mechanism by binding to different epitopes of an antigen is also discussed.

Experimental and theoretical investigation of cyclometallated platinum(ii) complex containing adamantanemethylcyanamide and 1,4-naphthoquinone derivative as ligands: synthesis, characterization, interacting with guanine and cytotoxic activity

A new cyclometallated platinum(ii) complex with 1-adamantanemethylcyanamide (1-ADpcydH) and 2-[amino(2-phenylpyridine)]-1,4-naphthoquinone (1,4-NQ) ligands with the formula cis-Pt(1,4-NQ)(1-ADpcyd)(H₂O) was synthesized and fully characterized. Cellular uptake, DNA platination, and cytotoxicity against human MCF-7 breast, HepG-2 liver hepatocellular carcinoma, and HT-29 colon cancer cell lines were evaluated. The interaction of guanine (G) with cis-Pt(1,4-NQ)(1-ADpcyd)(H₂O) was studied by ¹⁹⁵Pt NMR and mass spectroscopy. Furthermore, DFT calculations were performed on the complexes cis-Pt(1,4-NQ)(1-ADpcyd)(H₂O) 1 and cis-Pt(1,4-NQ)(1-ADpcyd)(G) 2 using the BP86-D and B3LYP functionals, in order to gain deeper insights into the molecular and electronic structures. Decomposition energy analysis gave a clear understanding of the bonding within both complexes, showing that the interactions were governed by two-third ionic and one-third covalent characters, which were stronger between the guanine and the Pt(ii) center than those between water and the Pt(ii).

A new cyclometallated platinum(ii) complex was synthesized and its characterization, interaction with guanine, and cytotoxic activity were investigated by experiment and theoretical calculations.

Structural analyses reveal the mechanism of inhibition of influenza virus NS1 by two antiviral compounds

The influenza virus is a significant public health concern causing 250,000-500,000 deaths worldwide each year. Its ability to change quickly results in the potential for rapid generation of pandemic strains for which most individuals would have no antibody protection. This pandemic potential highlights the need for the continuous development of new drugs against influenza virus. As an essential component and well established virulence determinant, NS1 (nonstructural protein 1) of influenza virus is a highly prioritized target for the development of anti-influenza compounds. Here, we used NMR to determine that the NS1 effector domain (NS1^ED) derived from the A/Brevig Mission/1/1918 (H1N1) strain of influenza (1918^H1N1) binds to two previously described anti-influenza compounds A9 (JJ3297) and A22. We then used X-ray crystallography to determine the three-dimensional structure of the 1918^H1N1 NS1^ED Furthermore, we mapped the A9/A22-binding site onto our 1918^H1N1 NS1^ED structure and determined that A9 and A22 interact with the NS1^ED in the hydrophobic pocket known to facilitate binding to the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30), suggesting that the two compounds likely attenuate influenza replication by inhibiting the NS1^ED-CPSF30 interaction. Finally, our structure revealed that NS1^ED could dimerize via an interface that we termed the α₃-α₃ dimer. Taken together, the findings presented here provide strong evidence for the mechanism of action of two anti-influenza compounds that target NS1 and contribute significant structural insights into NS1 that we hope will promote and inform the development and optimization of influenza therapies based on A9/A22.

Complexes of Oligoribonucleotides with d-Mannitol Modulate the Innate Immune Response to Influenza A Virus H1N1 (A/FM/1/47) In Vivo

Rapid replication of the influenza A virus and lung tissue damage caused by exaggerated pro-inflammatory host immune responses lead to numerous deaths. Therefore, novel therapeutic agents that have anti-influenza activities and attenuate excessive pro-inflammatory responses that are induced by an influenza virus infection are needed. Oligoribonucleotides-d-mannitol (ORNs-d-M) complexes possess both antiviral and anti-inflammatory activities. The current research was aimed at studying the ORNs-d-M effects on expression of innate immune genes in mice lungs during an influenza virus infection. Expression of genes was determined by RT-qPCR and Western blot assays. In the present studies, we found that the ORNs-d-M reduced the influenza-induced up-expression of Toll-like receptors (TLRs) (tlr3, tlr7, tlr8), nuclear factor NF-kB (nfkbia, nfnb1), cytokines (ifnε, ifnk, ifna2, ifnb1, ifnγ, il6, il1b, il12a, tnf), chemokines (ccl3, ccl4, сcl5, cxcl9, cxcl10, cxcl11), interferon-stimulated genes (ISGs) (oas1a, oas2, oas3, mx1), and pro-oxidation (nos2, xdh) genes. The ORNs-d-M inhibited the mRNA overexpression of tlr3, tlr7, and tlr8 induced by the influenza virus, which suggests that they impair the upregulation of NF-kB, cytokines, chemokines, ISGs, and pro-oxidation genes induced by the influenza virus by inhibiting activation of the TLR-3, TLR-7, and TLR-8 signaling pathways. By impairing activation of the TLR-3, TLR-7, and TLR-8 signaling pathways, the ORNs-d-M can modulate the innate immune response to an influenza virus infection.

Pre-Clinical and Clinical Efficiency of Complexes of Oligoribonucleotides with D-Mannitol against Respiratory Viruses

Oligoribonucleotides-D-mannitol (ORNs-D-M) complexes possess antiviral, anti-inflammatory, and immunomodulatory actions. The aim of the present study was to evaluated an antiviral effect of ORNs-D-M against parainfluenza virus type 3 (PIV3); influenza CA709, PR834; avian influenza virus H5N2 (AIV) in vitro by a TCID₅₀; hemadsorption and neuraminidase activity assays; and clinical efficiency of ORNs-D-M in patients with acute respiratory infections (ARIs) of various etiologies by PCR assay and AmpliSens test systems. It was observed that ORNs-D-M have an antiviral activity against the influenza CA709, PR834, PIV3, and AIV in vitro. The injectable dosage form of ORNs-D-M was shown to have a stronger antiviral effect compared to capsule form. It was also detected that the injectable form of ORNs-D-M significantly reduced the neuraminidase activity of influenza PR834. A complex treatment of patients with ORNs-D-M had a positive effect on the course of the disease, it accelerated patients’ recovery. Treatment with ORNs-D-M caused eradication of adeno- and influenza viruses in patients with ARI. This drug contributed to significant decrease in duration of febrile period and cough. Comprehensive treatment with ORNs-D-M improved the disease clinical findings significantly. Collectively, these results suggested that ORNs-D-M may be used at co-infection with influenza and other respiratory viruses as a medical antiviral drug.

A Highly Potent and Broadly Neutralizing H1 Influenza-Specific Human Monoclonal Antibody

Influenza’s propensity for antigenic drift and shift, and to elicit predominantly strain specific antibodies (Abs) leaves humanity susceptible to waves of new strains with pandemic potential for which limited or no immunity may exist. Subsequently new clinical interventions are needed. To identify hemagglutinin (HA) epitopes that if targeted may confer universally protective humoral immunity, we examined plasmablasts from a subject that was immunized with the seasonal influenza inactivated vaccine, and isolated a human monoclonal Ab (mAb), KPF1. KPF1 has broad and potent neutralizing activity against H1 influenza viruses, and recognized 83% of all H1 isolates tested, including the pandemic 1918 H1. Prophylactically, KPF1 treatment resulted in 100% survival of mice from lethal challenge with multiple H1 influenza strains and when given as late as 72 h after challenge with A/California/04/2009 H1N1, resulted in 80% survival. KPF1 recognizes a novel epitope in the HA globular head, which includes a highly conserved amino acid, between the Ca and Cb antigenic sites. Although recent HA stalk-specific mAbs have broader reactivity, their potency is substantially limited, suggesting that cocktails of broadly reactive and highly potent HA globular head-specific mAbs, like KPF1, may have greater clinical feasibility for the treatment of influenza infections.

Oroxylin A suppresses influenza A virus replication correlating with neuraminidase inhibition and induction of IFNs

Because it is highly contagious, the influenza A virus (IAV) has the potential to cause pandemics in humans. The emergence of drug-resistant strains requires the development of new chemical therapeutics. Oroxylin A (OA) is a flavonoid which has been shown to have antioxidant and antitumor effects. However, intensive studies in which OA fights against different influenza virus strains and the underlying antiviral mechanisms have not been reported. In our study, the antiviral activities in cells and in mice, the preliminary mechanisms of OA were investigated. Our data show that it can inhibit A/FM/1/47 (H1N1), A/Beijing/32/92 (H3N2) and oseltamivir-resistant A/FM/1/47-H275Y (H1N1-H275Y) viruses in MDCK cells in a dose-dependent manner with inhibitory rates of 70.9%, 59.5% and 23.2%, respectively, at 50μM doses. Orally administered OA effectively protected mice from H1N1 virus-induced death, body weight loss and lung injury, with a survival rate of 60.0% at 100mg/kg/d dose. In addition, the H1N1 M1 gene transcription and protein synthesis were suppressed by 43.7% and 33.2%, respectively, in the late biosynthesis stage. This resulted in inhibition of viral replication. Furthermore, we found that OA has a neuraminidase (NA) inhibitory effect with IC₅₀ values for H1N1-H275Y and A/Anhui/1/2013-R294K (H7N9-R294K) of 241.4μM and 203.6μM, respectively. Interferons (IFNs) produced by the virally infected cells play important roles in antiviral defense, therefore, IFN levels in the blood were also tested in mice. We found that IFN-β and IFN-γ in the OA 100mg/kg/d group were markedly increased by 24.5pg/mL and 859.9pg/mL, respectively, compared with those in the model group. This indicated that OA could induce the secretion of IFNs. The potent inhibition of virus replication and NA inhibitory activity, as well as the promotion of IFN production suggest that OA could be a drug candidate to fight against IAVs including oseltamivir-resistant strains.

Structure-based optimization and synthesis of antiviral drug Arbidol analogues with significantly improved affinity to influenza hemagglutinin

Influenza is a highly contagious respiratory viral infection responsible for up to 50,000 deaths per annum in the US alone. The need for new therapeutics with novel modes of action is of paramount importance. We determined the X-ray structure of Arbidol with influenza hemagglutinin and found it was located in a distinct binding pocket. Herein, we report a structure-activity relationship study based on the co-complex combined with bio-layer interferometry to assess the binding of our compounds. Addition of a meta-hydroxy group to the thiophenol moiety of Arbidol to replace a structured water molecule in the binding pocket resulted in a dramatic increase in affinity against both H3 (1150-fold) and H1 (98-fold) hemagglutinin subtypes. Our analogues represent novel leads to yield more potent compounds against hemagglutinin that block viral entry.

Influenza

Influenza is an acute respiratory illness, caused by influenza A, B, and C viruses, that occurs in local outbreaks or seasonal epidemics. Clinical illness follows a short incubation period and presentation ranges from asymptomatic to fulminant, depending on the characteristics of both the virus and the individual host. Influenza A viruses can also cause sporadic infections or spread worldwide in a pandemic when novel strains emerge in the human population from an animal host. New approaches to influenza prevention and treatment for management of both seasonal influenza epidemics and pandemics are desirable. In this Seminar, we discuss the clinical presentation, transmission, diagnosis, management, and prevention of seasonal influenza infection. We also review the animal-human interface of influenza, with a focus on current pandemic threats.

Complexes of Oligoribonucleotides with D-Mannitol Inhibit Hemagglutinin-Glycan Interaction and Suppress Influenza A Virus H1N1 (A/FM/1/47) Infectivity In Vitro

The influenza virus hemagglutinin (HA) mediates both receptor (glycan) binding and membrane fusion for cell entry and has been the basis for subtyping influenza viruses. The oligoribonucleotides-d-mannitol (ORNs-d-M) complexes possess an anti-influenza activity in vitro and in vivo. In the present studies, we have found that ORNs-d-M interferes with hemagglutinin (HA)–glycan interaction and suppress viral infection in host cells. HA–glycan interactions were evaluated to indirectly quantify the amount of influenza virus titer by an agglutination assay. Influenza virus infectivity was determined by TCID₅₀ assay. The direct virucidal action of the complexes was evaluated by both cytopathic effects (CPE) reduction assay and cell MTT assay. We found that ORNs-d-M hinders interaction between HA and glycan. These complexes decreased the infectivity of influenza virus and had a direct virucidal action. ORNs-d-M reduces influenza virus infectivity, affecting the HA–glycan interaction in vitro. By suppressing the influenza viral infection, the ORNs-d-M can have direct virucidal action.

Impact of Respiratory Virus Infections in Exacerbation of Acute and Chronic Rhinosinusitis

Rhinosinusitis (RS) is a symptomatic disease classification of many causes and is a major economic burden worldwide. It is widely accepted that RS is further classified into acute (ARS) and chronic (CRS) rhinosinusitis based on the duration of the symptoms, and that viral infection plays a large role in initiating or potentiating the disease. In this review, we examine the role of respiratory virus infection in the exacerbation of ARS and CRS. We explore the epidemiology of viral exacerbation of ARS and CRS and highlight key viruses that may cause exacerbation. We also review the current understanding of viral infections in the upper airway to further explain the putative underlying mechanisms of inflammatory events in ARS and CRS exacerbation. Advances in accurate diagnosis of the etiologic respiratory viruses of ARS and CRS symptoms which can lead to better disease management are also surveyed. In addition to the current treatments which provide symptomatic relief, we also explore the potential of harnessing existing antiviral strategies to prevent ARS and CRS exacerbation, especially with improved viral diagnostic tools to guide accurate prescription of antivirals against causative respiratory viruses.

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.

Human antibody 3E1 targets the HA stem region of H1N1 and H5N6 influenza A viruses

As influenza A viruses remain a major threat to human health worldwide, the discovery of broadly neutralizing monoclonal antibodies that recognize conserved epitopes would facilitate the development of antibody-based therapeutic strategies. Here we report that a V_H4-4-encoded human mAb named 3E1 could neutralize H1 and H5 subtype viruses in vitro and protect mice against the H1N1 and H5N6 viruses by inhibiting the low pH-induced conformational rearrangement of haemagglutinin (HA), hence blocking membrane fusion. The crystal structures of 3E1 Fab in complex with HA of two H1N1 strains reveal that 3E1, with both heavy and light chains, binds to a conserved epitope of the HA stem region, comprising parts of the fusion peptide, the F subdomain and the outermost β-strand preceding helix A. Altogether, these data suggest the potential of 3E1 as a therapeutic drug against H1 and H5 subtype viruses.

Inosine pranobex is safe and effective for the treatment of subjects with confirmed acute respiratory viral infections: analysis and subgroup analysis from a Phase 4, randomised, placebo-controlled, double-blind study

BACKGROUND

Inosine pranobex (Isoprinosine®) is an immunomodulatory drug approved in several countries for the treatment of viral infections. This study compared the efficacy and safety of inosine pranobex versus placebo in subjects with clinically diagnosed influenza-like illness, including subjects with laboratory-confirmed acute respiratory viral infections. Subgroup analyses evaluated the efficacy of inosine pranobex compared to placebo in otherwise healthy (without related ongoing disease) subjects that were less than 50 years of age and healthy subjects that were at least 50 years of age. The effect of body mass index (BMI) was evaluated in subjects less than 50 years of age.

METHODS

A total of 463 subjects were randomly assigned to receive inosine pranobex (n = 231) or placebo (n = 232) in this Phase 4, randomised, double-blind, multicentre study. The primary efficacy endpoint was time to resolution of all influenza-like symptoms present at baseline to none. Safety was evaluated through analysis of adverse events, vital signs, and physical examinations.

RESULTS

The difference in time to resolution of all influenza-like symptoms between treatment groups was not statistically significant but showed a faster improvement in subjects in the inosine pranobex group versus those in the placebo group - Hazard Ratio = 1.175; (95 % CI: 0.806-1.714). P-value = 0.324. In the subgroup analysis for subjects less than 50 years of age, statistically significant differences in time to resolution of influenza-like symptoms that favoured the inosine pranobex group over the placebo group were observed in those without related ongoing disease and those who were non-obese (BMI <30 kg/m²). The differences between the inosine pranobex and placebo groups in subjects at least 50 years of age without related ongoing disease and in subjects less than 50 years of age who were obese (BMI ≥30 kg/m²) were not statistically significant. Inosine pranobex was generally well tolerated, and no deaths were reported.

CONCLUSIONS

The study results indicate the safety of inosine pranobex for the treatment of subjects with confirmed acute respiratory viral infections and confirm the efficacy of inosine pranobex versus placebo in healthy non-obese subjects less than 50 years of age with clinically diagnosed influenza-like illnesses.

TRIAL REGISTRATION

EWO-ISO-2014/1, EudraCT 2014-001863-11 ; Date of registration: 29 APR 2014; Detail information web link: https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-001863-11/results.

Replication-Competent Influenza A Viruses Expressing Reporter Genes

Influenza A viruses (IAV) cause annual seasonal human respiratory disease epidemics. In addition, IAV have been implicated in occasional pandemics with inordinate health and economic consequences. Studying IAV, in vitro or in vivo, requires the use of laborious secondary methodologies to identify virus-infected cells. To circumvent this requirement, replication-competent IAV expressing an easily traceable reporter protein can be used. Here we discuss the development and applications of recombinant replication-competent IAV harboring diverse fluorescent or bioluminescent reporter genes in different locations of the viral genome. These viruses have been employed for in vitro and in vivo studies, such as the screening of neutralizing antibodies or antiviral compounds, the identification of host factors involved in viral replication, cell tropism, the development of vaccines, or the assessment of viral infection dynamics. In summary, reporter-expressing, replicating-competent IAV represent a powerful tool for the study of IAV both in vitro and in vivo.

Inhibition of endosomal fusion activity of influenza virus by Rheum tanguticum (da-huang)

Rhubarb (Rheum tanguticum; da-huang in Chinese medicine) is a herbal medicine that has been used widely for managing fever and removing toxicity. In this study, we investigated how rhubarb inhibits influenza virus during the early stage of the infectious cycle using different functional assays. A non-toxic ethanolic extract of rhubarb (Rex) inhibited several H1N1 subtypes of influenza A viruses in Madin–Darby canine kidney cells, including strains that are clinically resistant to oseltamivir. Time course analysis of Rex addition showed that viral entry was one of the steps that was inhibited by Rex. We also confirmed that Rex effectively inhibited viral attachment and penetration into the host cells. The inhibition of red blood cell haemolysis and cell–cell fusion by Rex suggests that Rex may block haemagglutinin-mediated fusion (virus–endosome fusion) during the fusion/uncoating step. Rex has the capacity to inhibit influenza viruses by blocking viral endocytosis. Thus, rhubarb might provide an alternative therapeutic approach when resistant viruses become more prevalent.

Mutations Designed by Ensemble Defect to Misfold Conserved RNA Structures of Influenza A Segments 7 and 8 Affect Splicing and Attenuate Viral Replication in Cell Culture

Influenza A virus is a significant public health threat, but little is understood about the viral RNA structure and function. Current vaccines and therapeutic options to control influenza A virus infections are mostly protein-centric and of limited effectiveness. Here, we report using an ensemble defect approach to design mutations to misfold regions of conserved mRNA structures in influenza A virus segments 7 and 8. Influenza A mutant viruses inhibit pre-mRNA splicing and attenuate viral replication in cell culture, thus providing evidence for functions of the targeted regions. Targeting these influenza A viral RNA regions provides new possibilities for designing vaccines and therapeutics against this important human respiratory pathogen. The results also demonstrate that the ensemble defect approach is an efficient way to test for function of RNA sequences.

Investigating the role of MRGPRC11 and capsaicin-sensitive afferent nerves in the anti-influenza effects exerted by SLIGRL-amide in murine airways

BACKGROUND

The hexapeptide SLIGRL-amide activates protease-activated receptor-2 (PAR-2) and mas-related G protein-coupled receptor C11 (MRGPRC11), both of which are known to be expressed on populations of sensory nerves. SLIGRL-amide has recently been reported to inhibit influenza A (IAV) infection in mice independently of PAR-2 activation, however the explicit roles of MRGPRC11 and sensory nerves in this process are unknown. Thus, the principal aim of this study was to determine whether SLIGRL-amide-induced inhibition of influenza infection is mediated by MRGPRC11 and/or by capsaicin-sensitive sensory nerves.

METHODS

The inhibitory effect of SLIGRL-amide on IAV infection observed in control mice in vivo was compared to effects produced in mice that did not express MRGPRC11 (mrgpr-cluster∆ (-/-) mice) or had impaired sensory nerve function (induced by chronic pre-treatment with capsaicin). Complementary mechanistic studies using both in vivo and ex vivo approaches investigated whether the anti-IAV activity of SLIGRL-amide was (1) mimicked by either activators of MRGPRC11 (BAM8-22) or by activators (acute capsaicin) or selected mediators (substance P, CGRP) of sensory nerve function, or (2) suppressed by inhibitors of sensory nerve function (e.g. NK1 receptor antagonists).

RESULTS

SLIGRL-amide and BAM8-22 dose-dependently inhibited IAV infection in mrgpr-cluster∆ (-/-) mice that do not express MRGPRC11. In addition, SLIGRL-amide and BAM8-22 each inhibited IAV infection in capsaicin-pre-treated mice that lack functional sensory nerves. Furthermore, the anti-IAV activity of SLIGRL-amide was not mimicked by the sensory neuropeptides substance P or CGRP, nor blocked by either NK1 (L-703,606, RP67580) and CGRP receptor (CGRP8-37) antagonists. Direct stimulation of airway sensory nerves through acute exposure to the TRPV1 activator capsaicin also failed to mimic SLIGRL-amide-induced inhibition of IAV infectivity. The anti-IAV activity of SLIGRL-amide was mimicked by the purinoceptor agonist ATP, a direct activator of mucus secretion from airway epithelial cells. Additionally, both SLIGRL-amide and ATP stimulated mucus secretion and inhibited IAV infectivity in mouse isolated tracheal segments.

CONCLUSIONS

SLIGRL-amide inhibits IAV infection independently of MRGPRC11 and independently of capsaicin-sensitive, neuropeptide-releasing sensory nerves, and its secretory action on epithelial cells warrants further investigation.

Characterization and pharmacological potential of Lactobacillus sakei 1I1 isolated from fresh water fish Zacco koreanus

BACKGROUND

There are still a large variety of microorganisms among aquatic animals which have not been explored for their pharmacological potential. Hence, present study was aimed to isolate and characterize a potent lactic acid bacterium from fresh water fish sample Zacco koreanus, and to confirm its pharmacological potential.

METHODS

Isolation of lactic acid bacteria (LAB) from fresh water fish samples was done using serial dilution method. Biochemical identification and molecular characterization of selected LAB isolate 1I1, based on its potent antimicrobial efficacy, was accomplished using API kit and 16S rRNA gene sequencing analysis. Further, 1I1 was assessed for α-glucosidase and tyrosinase inhibitory potential as well as antiviral efficacy against highly pathogenic human influenza virus H1N1 using MDCK cell line in terms of its pharmacological potential.

RESULTS

Here, we first time report isolation as well as biochemical and molecular characterization of a lactic acid bacterium Lactobacillus sakei 1I1 isolated from the intestine of a fresh water fish Z. koreanus. As a result, L. sakei 1I1 exhibited potent antimicrobial effect in vitro, and diameter of zones of inhibition of 1I1 against the tested pathogens was found in the range of 13.32 ± 0.51 to 23.16 ± 0.32 mm. Also L. sakei 1I1 at 100 mg/ml exhibited significant (p < 0.05) α-glucosidase and tyrosinase inhibitory activities by 60.69 and 72.59%, in terms of its anti-diabetic and anti-melanogenic potential, respectively. Moreover, L. sakei 1I1 displayed profound anti-cytopathic effect on MDCK cell line when treated with its ethanol extract (100 mg/ml), confirming its potent anti-viral efficacy against H1N1 influenza virus.

CONCLUSIONS

These findings reinforce the suggestions that L. sakei 1I1 isolated from the intestine of fresh water fish Z. koreanus might be a candidate of choice for using in pharmacological preparations as an effective drug.

Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs

West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin, and Amantadine), that are used as therapy for Parkinson's disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection.

Replication-competent fluorescent-expressing influenza B virus

Influenza B viruses (IBVs) cause annual outbreaks of respiratory illness in humans and are increasingly recognized as a major cause of influenza-associated morbidity and mortality. Studying influenza viruses requires the use of secondary methodologies to identify virus-infected cells. To this end, replication-competent influenza A viruses (IAVs) expressing easily traceable fluorescent proteins have been recently developed. In contrast, similar approaches for IBV are mostly lacking. In this report, we describe the generation and characterization of replication-competent influenza B/Brisbane/60/2008 viruses expressing fluorescent mCherry or GFP fused to the C-terminal of the viral non-structural 1 (NS1) protein. Fluorescent-expressing IBVs display similar growth kinetics and plaque phenotype to wild-type IBV, while fluorescent protein expression allows for the easy identification of virus-infected cells. Without the need of secondary approaches to monitor viral infection, fluorescent-expressing IBVs represent an ideal approach to study the biology of IBV and an excellent platform for the rapid identification and characterization of antiviral therapeutics or neutralizing antibodies using high-throughput screening approaches. Lastly, fluorescent-expressing IBVs can be combined with the recently described reporter-expressing IAVs for the identification of novel therapeutics to combat these two important human respiratory pathogens.

Infectious Diseases and the Kidney in Children

The kidney is involved in a wide range of bacterial, viral, fungal, and parasitic diseases. In most systemic infections, renal involvement is a minor component of the illness, but in some, renal failure may be the presenting feature and the major problem in management. Although individual infectious processes may have a predilection to involve the renal vasculature, glomeruli, interstitium, or collecting systems, a purely anatomic approach to the classification of infectious diseases affecting the kidney is rarely helpful because most infections may involve several different aspects of renal function. In this chapter, a microbiological classification of the organisms affecting the kidney is adopted. Although they are important causes of renal dysfunction in infectious diseases, urinary tract infections and hemolytic uremic syndrome (HUS) are not discussed in detail because they are considered separately in chapters XX and XX, respectively.

Oseltamivir for influenza infection in children: risks and benefits

Influenza is a common disease affecting many children each year. In a number of cases, particularly in children <2 years old and in those with severe chronic underlying disease, influenza can be complicated by lower respiratory tract infections, acute otitis media, rhinosinusitis, febrile seizures, dehydration or encephalopathy. Oseltamivir is the influenza virus drug that is most commonly studied in children for both the treatment and prevention of influenza. To avoid the risk that children with mild influenza or patients suffering from different viral infections receive oseltamivir, oseltamivir treatment should be recommended only in severe influenza cases, especially if confirmed by reliable laboratory tests. However, therapy must be initiated considering the risk of complications and the presence of severe clinical manifestations at age- and weight-appropriate doses. Because the vaccine remains the best option for preventing influenza and its complications, prophylaxis using oseltamivir should only be considered in select patients.