Antiviral Drug Amantadine Research Articles

Computational investigation in inhibitory effects of amantadine on classical swine fever virus p7 ion channel activity

Classical swine fever virus (CSFV) p7 viroporin plays crucial roles in cellular ion balance and permeabilization. The antiviral drug amantadine effectively inhibits viral replication by blocking the activity of CSFV p7 viroporin. However, little information is available for the binding mode of amantadine with CSFV p7 viroporin, due to the lack of a known polymer structure for CSFV p7. In this study, we employed AlphaFold2 to predict CSFV p7 structures. Subsequently, we conducted a docking study to investigate the binding sites of amantadine to CSFV p7. Computational analysis showed that CSFV p7 forms a pore channel in a hexameric structure. Furthermore, molecular dynamics (MD) simulations and mutant analyses further suggest that CSFV p7 likely exists as a hexamer. Docking studies and MD simulations showed that amantadine interacts with the hydrophibic regions of tetramer and pentamer, as well as with the hydrophobic pore channel of the hexamer. Considering the potential hexameric assembly of CSFV p7, along with docking results, MD simulations, and the characteristics of the gated ion channels, we propose a model of CSFV p7 ion channel based on its hexameric configuration. In this model, residues E21, Y25, and R34 are suggested to selectively recruit and dehydrate ions, while residues L28 and L31 likely act as hydrophobic constrictors, thereby restricting the free movement of water. The binding of amantadine to residues I20, E21, V24 and Y25 effectively blocks ion transport. However, this proposed molecular model requires experimental validation. Our findings give a structural insight into the models of CSFV p7 as an ion channel and provide a molecular explanation for the inhibition effects of amantadine on CSFV p7-mediated ion channel conductance.

Flow analysis-solid phase extraction system and UHPLC-MS/MS analytical methodology for the determination of antiviral drugs in surface water

An automated flow analysis-solid phase extraction (FA-SPE) system and methodology of ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) analysis were developed for the determination of selected antiviral drugs (acyclovir, amantadine, rimantadine, and oseltamivir) in water samples. The proposed FA-SPE approach enables the integration of various extraction stages and elimination of the sample evaporation step and offers individual customisation of SPE parameters, inter alia sample, and eluate flow rate and volume. Using the developed FA-SPE procedure, e.g. a 100-fold preconcentration of the target analytes in 1 h was achieved. A method for chromatographic analysis was also developed to determine the selected antiviral drugs in combination with the use of the FA-SPE system. The developed FA-SPE UHPLC-MS/MS method was validated including the determination of linearity of analytical graphs, limits of detection (5.5–99.9 pg mL−1) and quantification (18.3–329.8 pg mL−1), intra-day (1.8–8.3%) and inter-day (3.0–9.2%) precision, recovery (95.6–105.3%), and matrix effects (− 12.9 to 13.2%). The proposed method was successfully applied to analyse tap, drinking, and river water samples, revealing the presence of amantadine at a concentration of 40.1 pg mL−1 in one sample. The environmental impact of the developed FA-SPE sample preparation procedure was also assessed using the AGREEprep metric tool and compared with five other literature methods, achieving the most sustainable outcome.Graphical abstract

Efficient one-pot process for synthesis of antiviral drug amantadine hydrochloride

Efficient one-pot process for synthesis of antiviral drug amantadine hydrochloride

Stability and WBE biomarkers possibility of 17 antiviral drugs in sewage and gravity sewers

Wastewater-based epidemiology (WBE) is a promising technique for monitoring the rapidly increasing use of antiviral drugs during the COVID-19 pandemic. It is essential to evaluate the in-sewer stability of antiviral drugs in order to determine appropriate biomarkers. This study developed an analytical method for quantification of 17 typical antiviral drugs, and investigated the stability of target compounds in sewer through 4 laboratory-scale gravity sewer reactors. Nine antiviral drugs (lamivudine, acyclovir, amantadine, favipiravir, nevirapine, oseltamivir, ganciclovir, emtricitabine and telbivudine) were observed to be stable and recommended as appropriate biomarkers for WBE. As for the other 8 unstable drugs (abacavir, arbidol, ribavirin, zidovudine, ritonavir, lopinavir, remdesivir and efavirenz), their attenuation was driven by adsorption, biodegradation and diffusion. Moreover, reaction kinetics revealed that the effects of sediments and biofilms were regarded to be independent in gravity sewers, and the rate constants of removal by biofilms was directly proportional to the ratio of surface area against wastewater volume. The study highlighted the potential importance of flow velocity for compound stability, since an increased flow velocity significantly accelerated the removal of unstable biomarkers. In addition, a framework for graded evaluation of biomarker stability was proposed to provide reference for researchers to select suitable WBE biomarkers. Compared with current classification method, this framework considered the influences of residence time and different removal mechanisms, which additionally screened four antiviral drugs as viable WBE biomarkers. This is the first study to report the stability of antiviral drugs in gravity sewers.

Aminoadamantanes: from treatment of Parkinson’s and Alzheimer’s disease to symptom amelioration of long COVID-19 syndrome?

ABSTRACT Introduction The aminoadamantanes amantadine and memantine are well known. They mainly act as N-methyl-D-aspartate antagonists. Areas covered The antiviral drug amantadine moderately ameliorates impaired motor behavior in patients with Parkinson’s disease. Memantine provides beneficial effects on memory function in patients with advanced Alzheimer’s disease already treated with acetylcholine esterase inhibitors. Both compounds counteract impaired monoamine neurotransmission with associated symptoms, such as depression. They improve vigilance, lack of attention and concentration, fatigue syndromes according to clinical findings in patients with chronic neurodegenerative processes. Their extrasynaptic N-methyl-D-Aspartate receptor blockade weakens a prolonged influx of Ca2+ ions as the main responsible components of neuronal excitotoxicity. This causes neuronal dying and associated functional deficits. Expert opinion We suggest aminoadamantanes as future therapies for amelioration of short- and long-term consequences of a COVID 19 infection. Particularly the extended-release amantadine formulations will be suitable. They showed better clinical efficacy compared with the conventional available compounds. Amantadine may particularly be suitable for amelioration of fatigue or chronic exhaustion, memantine for improvement of cognitive deficits. Clinical research in patients, who are affected by the short- and long-term consequences of a COVID 19 infection, is warranted to confirm these still hypothetical putative beneficial effects of aminoadamantanes.

Mechanistic basis for multidrug resistance and collateral drug sensitivity conferred to the malaria parasite by polymorphisms in PfMDR1 and PfCRT.

Polymorphisms in the Plasmodium falciparum multidrug resistance protein 1 (pfmdr1) gene and the Plasmodium falciparum chloroquine resistance transporter (pfcrt) gene alter the malaria parasite’s susceptibility to most of the current antimalarial drugs. However, the precise mechanisms by which PfMDR1 contributes to multidrug resistance have not yet been fully elucidated, nor is it understood why polymorphisms in pfmdr1 and pfcrt that cause chloroquine resistance simultaneously increase the parasite’s susceptibility to lumefantrine and mefloquine—a phenomenon known as collateral drug sensitivity. Here, we present a robust expression system for PfMDR1 in Xenopus oocytes that enables direct and high-resolution biochemical characterizations of the protein. We show that wild-type PfMDR1 transports diverse pharmacons, including lumefantrine, mefloquine, dihydroartemisinin, piperaquine, amodiaquine, methylene blue, and chloroquine (but not the antiviral drug amantadine). Field-derived mutant isoforms of PfMDR1 differ from the wild-type protein, and each other, in their capacities to transport these drugs, indicating that PfMDR1-induced changes in the distribution of drugs between the parasite’s digestive vacuole (DV) and the cytosol are a key driver of both antimalarial resistance and the variability between multidrug resistance phenotypes. Of note, the PfMDR1 isoforms prevalent in chloroquine-resistant isolates exhibit reduced capacities for chloroquine, lumefantrine, and mefloquine transport. We observe the opposite relationship between chloroquine resistance-conferring mutations in PfCRT and drug transport activity. Using our established assays for characterizing PfCRT in the Xenopus oocyte system and in live parasite assays, we demonstrate that these PfCRT isoforms transport all 3 drugs, whereas wild-type PfCRT does not. We present a mechanistic model for collateral drug sensitivity in which mutant isoforms of PfMDR1 and PfCRT cause chloroquine, lumefantrine, and mefloquine to remain in the cytosol instead of sequestering within the DV. This change in drug distribution increases the access of lumefantrine and mefloquine to their primary targets (thought to be located outside of the DV), while simultaneously decreasing chloroquine’s access to its target within the DV. The mechanistic insights presented here provide a basis for developing approaches that extend the useful life span of antimalarials by exploiting the opposing selection forces they exert upon PfCRT and PfMDR1.

Amantadine resistance of clade 2.3.2 H5N1 Avian Influenza Virus from Waterfowl in Indonesia

The objective of this research was to know the sensitivity of H5N1 clade 2.3.2 AIV from Indonesia to antiviral drug (amantadine) through molecular and in vitro tests. The study was conducted by virus isolation and identification, nucleotide analysis, and susceptibility to the amantadine hydrocloride in MDCK cells. The study result represented that the mean EID<sub>50 </sub>isolates of H5N1 clade 2.3.2 AIV was determined of >10<sup>8 </sup>EID<sub>50</sub>/ml. The analysis of phylogenetic tree of M2 gene from six viruses of H5N1 clade 2.3.2 AIV from Indonesia were closed with H5N1 clade 2.3.2 AIV avian influenza viruses from Vietnam, China, Hongkong. The substitution of M2 protein (V27I) was identified in six isolates H5N1 clade 2.3.2 AIV isolated from Indonesia. Avian influenza of clade 2.3.2 H5N1 subtype from Indonesia produced the formation of CPE and the positive HA reaction with non-toxic concentration of amantadine hydrochloride in MDCK cells. The result of genetic analysis of M2 gene for amantadine resistance was related with the results of HA test and the formation of CPE in MDCK cells. These results established that amantadine resistance have been identified in H5N1 clade 2.3.2 AIV viruses isolated from Indonesia

Synthesis, characterization, X-ray crystallography analysis and cell viability study of (η6-p-cymene)Ru(NH2R)X2 (X = Cl, Br) derivatives

Studies over the past few decades demonstrate the potential for metallodrugs as bioactive therapeutics. Here, we describe six new ruthenium(II) complexes with the general motif of (η6-p-cymene)Ru(NH2R)X2, where NH2R is either the influenza A antiviral drugs rimantadine or amantadine or the N-methyl-d-aspartate [NMDA] receptor antagonist, memantine and X = Cl or Br. All complexes were synthesized in high yield and purity and characterized by NMR spectroscopy and X-ray crystallography. Both the chlorine and bromine ruthenium(II) p-cymene complexes demonstrated cellular toxicity profiles similar to their respective free ligand, indicating that complexation to ruthenium(II) centers does not significantly increase toxicity of the bioactive ligand.

Two phytocompounds from Schinopsis brasiliensis show promising antiviral activity with multiples targets in Influenza A virus.

Influenza A virus, the main flu agent, affects billions of people worldwide. Conventional treatments still present limitations related to drug-resistance and severe side effects. As a result, natural product-derived molecules have been increasingly investigated as prospect drug candidates. Therefore, the aim of this study was to investigate the possible anti-flu activity and to evaluate the toxicity and pharmacokinetic parameters, by in silico approaches, of the Schinopsis brasiliensis Engl. phytochemical compounds. Nine phytocompounds and six antiviral drugs (Amantadine, Umifenovir, Favipiravir, Nitazoxanide, Oseltamivir, Zanamivir) were selected for the analyses against four Influenza A proteins: neuraminidase, polymerase basic protein 2, hemagglutinin and M2 ion channel protein. The molecular docking, the predicted antiviral activity, the predicted toxicity and the pharmacokinetics investigations were conducted. The obtained results demonstrated that Syringaresinol and Cycloartenone display promising in silico antiviral activity (binding energy < 5.0 and ≥ 9.0 kcal/mol) and safety (low toxicity than commercial anti-flu drugs). Overall, this study corroborated the hypothesis that S. brasiliensis barks extract has a biological activity against Influenza A virus. Additionally, Syringaresinol and Cycloartenone have multiple targets in Influenza A virus and showed themselves as the most promising phytocompounds to be isolated and considered for the therapeutic arsenal against the flu.

The Structure, Function, and Pathobiology of the Influenza A and B Virus Ion Channels.

Influenza A virus AM2 protein is an integral membrane protein that is an ion channel (also known as a viroporin). The channel has 24 extracellular residues, 19 residues that span the membrane once and acts as both the channel pore and also the membrane anchoring domain, and a 54-residue cytoplasmic tail. The M2 protein has four identical chains linked via two disulfide bonds that form a four-helix bundle that is 107-108 more permeable to protons than Na+ ions. The M2 channel is activated by low pH, His residue 37 is the pH sensor, and Trp residue 41 is the channel gate. The channel is blocked by the antiviral drug amantadine hydrochloride. The influenza B virus BM2 protein does not have homology with the AM2 channel, but BM2 does have the His proton sensor, Trp gate, and is activated by low pH. It is thought that the AM2 and BM2 proteins have common functions in the influenza A and B virus life cycles. Both BM2 and AM2 also facilitate virus budding. The amphipathic helix in the AM2 cytoplasmic tail has an important role in the assembly of the virus, and functional AM2 protein makes the virus independent of the "endosomal sorting complex required for transport" (ESCRT) complex scission.

Fabrication and evaluation of a label-free piezoelectric immunosensor for sensitive and selective detection of amantadine in foods of animal origin.

A label-free piezoelectric immunosensor was fabricated and applied to the detection of the antiviral drug amantadine (AM) in foods of animal origin. Experimental parameters associated with the fabrication and measurement process were optimized and are discussed here in detail. The proposed piezoelectric sensor is based on an immunosuppression format and uses a portable quartz crystal microbalance (QCM) chip. It was found to provide a good response to AM, with a sensitivity and limit of detection (LOD) of 33.9 and 1.3ngmL-1, respectively, as well as low cross-reactivity (CR, < 0.01%) with AM analogues. The immunosensor was further applied to quantify AM at three levels in spiked samples of typical foods of animal origin, and yielded recoveries of 83.2-93.4% and standard deviations (SDs, n = 3) of 2.4-4.5%, which are comparable to the results (recoveries: 82.6-94.3%; SDs: 1.7-4.2%) obtained using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. Furthermore, the piezoelectric immunosensing chip can be regenerated multiple (at least 20) times with low signal attenuation (about 10%). A sample analysis can be completed within 50min (sample pretreatment: about 40min, QCM measurement: 5min). These results demonstrate that the developed piezoelectric immunosensor provides a sensitive, accurate, portable, and low-cost analytical strategy for the antiviral drug AM in foods of animal origin, and this label-free detection method could also be applied to analyze other targets in the field of food safety. Graphical abstract.

Physico-chemical studies on binary aqueous solutions of Anti-Viral Influenza drugs

The ultrasonic velocity, density, viscosity and absorption have been measured for solution of Influenza Anti-Viral drugs (Amantadine and Oseltamivir) are presented at room temperature 303K. By taking measurements of Anti Influenza Viral drugs at 0.2, 0.4 and 0.6% concentrations of each solution. The aim of the study is to increase the solubility, stability, sweetness of drugs by the formation of complexation. The ultrasonic velocity, density and viscosity have been measured at 2MHz for the aqueous solutions of (i) Influenza Anti-Viral Drugs + HPMC (Hydroxy Propyl Methyl Cellulose), Lactose and CaCl2 (Calcium Chloride at different concentrations at a temperature 303K.The acoustical parameters such as adiabatic compressibility (β), intermolecular free length (Lf), internal pressure (πi), Rao's constant (R), relaxation time (τ), acoustical impedance (Za), absorption coefficient (α/f2), free volume (Vf), cohesive energy and solvation number (Sn) have been computed. These properties are attributed to solute-solvent interactions through hydrogen bonding, segment-segment interaction, molecular association, polymer-solvent interaction, polymer-polymer interaction and etc. The total absorption can be considered as the sum of contributions from solute-solvent interactions. These results are further supported by FTIR studies.

Indirect competitive ELISA and colloidal gold-based immunochromatographic strip for amantadine detection in animal-derived foods

In this research, an indirect competitive enzyme-linked immunosorbent assay (ELISA) and colloidal gold-based immunochromatographic (GICG) strip were developed for the detection of the antiviral drug amantadine (AM) in animal-derived foods.

Inhibitors of the M2 Proton Channel Engage and Disrupt Transmembrane Networks of Hydrogen-Bonded Waters

Water-mediated interactions play key roles in drug binding. In protein sites with sparse polar functionality, a small-molecule approach is often viewed as insufficient to achieve high affinity and specificity. Here we show that small molecules can enable potent inhibition by targeting key waters. The M2 proton channel of influenza A is the target of the antiviral drugs amantadine and rimantadine. Structural studies of drug binding to the channel using X-ray crystallography have been limited because of the challenging nature of the target, with the one previously solved crystal structure limited to 3.5 Å resolution. Here we describe crystal structures of amantadine bound to M2 in the Inwardclosed conformation (2.00 Å), rimantadine bound to M2 in both the Inwardclosed (2.00 Å) and Inwardopen (2.25 Å) conformations, and a spiro-adamantyl amine inhibitor bound to M2 in the Inwardclosed conformation (2.63 Å). These X-ray crystal structures of the M2 proton channel with bound inhibitors reveal that ammonium groups bind to water-lined sites that are hypothesized to stabilize transient hydronium ions formed in the proton-conduction mechanism. Furthermore, the ammonium and adamantyl groups of the adamantyl-amine class of drugs are free to rotate in the channel, minimizing the entropic cost of binding. These drug-bound complexes provide the first high-resolution structures of drugs that interact with and disrupt networks of hydrogen-bonded waters that are widely utilized throughout nature to facilitate proton diffusion within proteins.

Amantadine May Reduce Aggression in TBI Patients

Back to table of contents Previous article Next article PsychopharmacologyFull AccessAmantadine May Reduce Aggression in TBI PatientsJoAnn BlakeJoAnn BlakeSearch for more papers by this authorPublished Online:26 Dec 2017https://doi.org/10.1176/appi.pn.2018.pp11b1AbstractIf carefully administered and monitored, amantadine could have a promising role in reducing aggression in people with chronic brain injury.The antiviral drug amantadine may reduce aggression in people with chronic traumatic brain injury (TBI)—defined as symptoms lasting for more than six months post-injury, according to a study published in the September/October issue of the Journal of Head Trauma Rehabilitation. The study did not find a beneficial effect on anger, another common behavioral symptom of chronic TBI.While patients reported improvements on amantadine, Flora Hammond, M.D., explained it can take longer for family and friends to conclude that aggressive behavior has changed. Indiana University“Several analyses of participant ratings demonstrated superior improvement in the magnitude and frequency of change in aggression” among individuals who took amantadine 100 mg twice daily compared with placebo, Flora M. Hammond, M.D., chair of the Indiana University School of Medicine Department of Physical Medicine and Rehabilitation, and colleagues wrote. Each study participant was required to enlist an observer—someone close enough to the participant with TBI to have regular interactions and witness behavior—to answer questions about changes in aggression and anger over the course of the trial. According to the study, the reported decrease in aggression in the amantadine group was based on reports from the perspective of the person with brain injury, not from the observer. “For observers, more so than for participants, the changes in aggressive behavior may need to be sustained over a longer time before observers are willing to conclude that the behavior has changed,” wrote Hammond in an email to Psychiatric News. Substantial improvements were found in both amantadine and placebo groups (70 percent versus 56 percent), suggesting that participation the trial alone had a positive impact on the patients. Aggression can have devastating effects on people’s lives and ability to function, Hammond said. “Having a variety of medications to choose from allows selection of the agent that may be most appropriate for the individual,” she wrote, adding that amantadine is cleared from the body by the kidneys and it should not be given to dialysis patients or individuals with inadequate creatinine clearance. The study included 118 patients with TBI who had moderate to severe aggression at baseline. Of these, 61 were randomized to amantadine and 57 to placebo. Anger and aggression were measured at treatment days 0, 28, and 60 using observer-rated and participant-rated State-Trait Anger Expression Inventory-2 (STAXI-2) and Neuropsychiatric Inventory-Agitation/Aggression domain (NPI-A) Most Problematic and Distress scores. The NPI-A domain asks whether during the preceding month the person “got upset, resisted activities, shouted, cursed angrily, slammed doors, kicked furniture, threw things, hurt or hit others, or was stubborn, uncooperative, or hard to handle.” Anger and aggression are related but are two distinct behaviors tested by the study. “Anger is a state of negative feeling that may be associated with hostile thoughts. Anger may be experienced internally or externally, but aggression is an externally expressed anger. Although anger and aggression may occur concurrently, they are not equivalent,” Hammond wrote. “Aggression may have important links to arousal modulation and function. Thus, medications that enhance arousal could also have modulating effect on aggression. In contrast, anger is likely to be a more static condition, and possibly mediated in part by serotonin,” she commented. The research was supported by the U.S. Department of Education, Office of Special Education and Rehabilitative Services, National Institute on Disability, Independent Living, and Rehabilitation Research grant. ■Back to Psychopharmacology Newsletter Table of ContentsBack to Psychopharmacology Newsletter Table of Contents ISSUES NewArchived

Thermodynamics of the Antiviral and Antiparkinsonian Drug Amantadine Hydrochloride: Condensed State Properties and Decomposition

Heat capacities of the antiviral and antiparkinsonian drug amantadine hydrochloride in the crystalline state were measured by adiabatic and differential scanning calorimetry in the temperature range from 5 K to 470 K. Two unresolved low-enthalpy solid-to-solid phase transitions with peak maxima at 120.0 K and 123.1 K were detected. Thermodynamic functions for crystalline amantadine hydrochloride were derived from the data obtained. Decomposition of amantadine hydrochloride was studied by the Knudsen effusion method. Quantum chemical calculations supported completeness of the amantadine hydrochloride ionic pair disintegration under the effusion conditions. A data treatment model considering the difference in effusion rates of the decomposition products, anisotropy failure in the vicinity of the orifice, and vapor undersaturation in the effusion cell was developed. Thermodynamic parameters for the decomposition were thus derived and shown to be consistent with available literature data on decomposition of s...

Propagation of Influenza Virus in Lymphocytes Determine by Antiviral Effects of Honey, Ginger and Garlic Decoction

Three influenza A virus isolates, one from a human, one from a chicken, and one from a wild bird dropping, were used to infect human peripheral blood mononuclear cells (PBMCs) in culture. The influenza strains were H1N, H5/H7-N1/N2 (mixture) and H9N, respectively and were assessed in vitro in human PBMCs in the presence of Phytohemagglutinin (PHA). Viral replication was estimated by visual cytopathic effect (CPE). H1N2 CPE included budding of lymphocytes, fusion of infected cells with neighboring lymphocytes, and syncytial formation. H5/H7- N1/N2 and H9N2 each caused CPE that included bulging of cells with large vacuoles. The supernatant of infected lymphocyte culture was used to infect MDCK cell lines. Influenza viral RNA was detected in extracts of MDCK cell lines and from lymphocytes infected with each of the three virus strains as judged by RT-PCR, confirming that all three isolates were able to replicate in human lymphocytes in vitro. The antiviral activity of a mixture of honey, ginger, and garlic (HGG) extracts, an over the counter drug commonly used in Pakistan to treat patients with influenza virus, was compared to the antiviral drug amantadine for its ability to decrease replication of the H1N2 strain in human PBMCs in vitro. HGG significantly inhibited H1N2 virus growth as judged by CPE, haemagglutination assays, and qRT-PCR. Interestingly, HGG also appeared to promote proliferation of human lymphocytes. These finding suggest that a mixture of crude extracts from honey, ginger, and garlic may be clinically useful against influenza virus.

M2 As a Target to Combat Influenza Drug Resistance: What Does the Evidence say?

*Department of Pharmacology & Toxicology, College of Pharmacy & the BIO5 Institute, The University of Arizona, 1657 E. Helen St., Tucson, AZ 85718, USA; Tel.: +001 520 626 1366; junwang@pharmacy.arizona.edu AM2 was first discovered as the drug target of the antiviral drug amantadine [1]. From a personal perspective, I find both the drug and the target to be fascinating: amantadine is a synthetic cage-shaped small molecule without violations of bond lengths or bond angles and fits snuggly in the wildtype M2 channel cavity; AM2 is the smallest ion channel that is highly selective for protons versus sodium and potassium ions. Soon after their discovery, they immediately caught scientists’ attention: what is the structural basis for proton selectivity of this small protein with only 97 residues? How does amantadine bind to the AM2 channel? These are key questions that need to be addressed in searching for the nextgeneration AM2 channel blockers. It was subsequently revealed that the functional unit of AM2 is a tetramer assembled by four identical monomers through transmembrane helix–helix interactions [2]. Proton selectivity is encoded by the highly conserved H 37 XXW 41 selectivity filter. Although the exact molecular mechanism of how protons are shuttled through the HXXW motif is still under debate [3], the general consensus is that when hydronium diffuses into the AM2 channel cavity and reaches the H37, the protonated H37s experience charge repulsion, which leads to a conformational change from the open out close in to the close out -open in conformers [4]. The proton is then released into the viral interior. This is followed by the relaxation of the M2 channel from the close out -open in to open out -close in conformation for the next round of proton shuttling. Regarding the mechanism of channel inhibition by amantadine, it was proposed that when amantadine fits into the central cavity of AM2 above the H37, it prevents the conformational change from open out -close in to close out -open in , thus halting the proton conductance [5]. M2 is a proven drug target. It is absolutely essential for influenza virus replication: silencing the AM2 gene or blocking the AM2 proton conductance by amantadine leads to inhibition of viral replication [6]. “...it is almost impossible to completely eliminate drug resistance issues of antiviral drugs, regardless of whether they are direct-acting antivirals or host-targeting antivirals.”

The experience of domestic antiviral agents, and some of own approaches in the treatment of chronic hepatitis C in adults

In the management of 148 adult patients with chronic hepatitis C (CHC) of both sexes without special selection (taken into account only absolute contraindications to its performance) there were used domestic basic antiviral drugs - BAD\ (short-living interferons (IFN) a, interferon inducers and nucleoside analogues) in parallel with additional antiviral drugs (drug glycyrrhizinic acid or amantadine) and maintenance therapy (stimulators of T-cell immunity and means of correction of side effects). Treatment was carried out in the framework of the developed complex of principles and approaches including in part, the formation of the starting average weekly dose of interferon IFN with accounting of the character of interferon status of the patient, a gradual increase in the average weekly dose of interferon IFN during the course of therapy, the delayed use of nucleoside analogs and others. As a result, against the background of a significant reduction in financial expenses and the aggressiveness of treatment the stable positive therapeutic outcome in the general population ofpatients occurred in 92.6%, with 87.2% in patients with genotype (G) 1.

Dynamics of M2 Proton Channel: Insights into the Motions of the Primary and Secondary Gates

M2 proton channel is essential for Influenza A life cycle. The antiviral drug amantadine (AMT) used to block the M2 channel prior to the recent S31N mutation. Based on the abundant structural information on M2 we have characterized backbone and side-chain motions for Trp41 and Val27, in constructs of the transmembrane domain (M2TM) and the full length M2 protein (M2FL) reconstituted in lipid bilayers. M2 proton permeation has been shown to be dependent on the His37-Trp41 cluster, where Trp41 is the primary gate. Proton conductance directionality is lost upon Trp41 mutation. We have characterized the global rotation motion of M2TM using 2H ssNMR. Interestingly, M2TM and M2FL have very similar dynamics for the backbone and side-chain of Trp41, as indicated by the 15N powder spectra of the Trp41 site labeled in both constructs. The collapsed powder spectra of 15NεTrp41 in M2FL and M2TM indicate that Trp41 side chain undergoes motion on a fast time scale. The separated local field spectrum of aligned M2TM indicates that Trp41 side-chain is undergoing large amplitude motion that broadens the 15Nε peak. The mean orientation for the Trp41 is being determined for M2TM and M2FL, moreover the effect of AMT binding and pH activation is being addressed. We also derived the motional model of Val27 side-chain, considered a secondary gate for M2 and essential for AMT inhibition on the wild type protein. The side-chain of Val27 undergoes a two site jump motion about the Cα-Cβ bond, with unequal populations. The addition of AMT induced line broadening and a significant increase in T2 (T2apo = 27 +- 7 μs T2drug=43 +- 3 μs). The spectra of the same site on the mutant protein (M2TM_S31N-d8Val27) showed no changes upon addition of Amt.