Inhibition of influenza hemagglutinin with the antiviral inhibitor arbidol using a proteomics based approach and mass spectrometry

A proteomics gel electrophoresis based approach has been applied to study the effect of arbidol on the proliferation of influenza virus in vitro through quantitation of hemagglutinin levels. An arbidol concentration of 20 μg/ml was required to achieve a 50% reduction in virus proliferation and hemagglutinin levels. The use of a MALDI mass spectrometry approach to study the binding of arbidol to influenza hemagglutinin revealed it bound solely to residues 104–120 of the HA2 subunit, a region known to contain an arbidol resistance mutation. Parallel molecular docking results revealed that this binding site was favoured in which the arbidol molecule binds in two possible orientations approximately 180° to one another at HA2 residues 118–123. The combined studies support the recognized potential of arbidol as an effective and targeted antiviral agent against the influenza virus.     

Biological evaluation of anti-influenza viral activity of semi-synthetic catechin derivatives

Catechin derivatives with different alkyl chain length and aromatic ring substitutions at the 3-hydroxyl group were synthesized from epigallocatechin (EGC) and (+)-catechin (C) and their anti-influenza viral activity were evaluated in vitro and in ovo. Pronounced antiviral activity was observed for derivatives carrying moderate chain length (7-9 carbons) as compared to those with aromatic rings, whereas the 5'-hydroxyl group of the trihydroxy benzyl moiety did not significantly contribute to antiviral activity. The derivatives exerted inhibitory effects for all six influenza subtypes tested including three major types of currently circulating human influenza viruses (A/H1N1, A/H3N2 and B type), H2N2 and H9N2 avian influenza virus. The compounds strongly inhibited adsorption of the viruses on red blood cell (RBC). They also restricted the growth of avian influenza virus in ovo with minimum inhibition concentration (MIC) of 5-10 microM far exceeding the neuraminidase (NA) inhibitor oseltamivir or M2 proton channel inhibitor amantadine. The antiviral activity appears to be mediated by interaction with hemagglutinin (HA)/viral membrane rendering HA less fusogenic at the initial stage of infection. The broad spectrum activity against various subtypes of influenza viruses may complement the limitations of current antivirals and contribute for managing potentially emerging influenza pandemic. The structure-activity data of catechin derivatives may usefully guideline future research endeavors for applying green tea catechins as alternative anti-viral agents.     

Antisense oligonucleotides targeting the RNA binding region of the NP gene inhibit replication of highly pathogenic avian influenza virus H5N1

The H5N1 avian influenza virus (AIV) causes widespread infections in bird and human respiratory tracts, and vaccines and drug therapy are limited in their effectiveness. Recent studies of AIV structures have been published and provide new targets for designing antiviral drugs such as antisense oligonucleotides (AS ODNs), which effectively inhibit gene replication. In this study, we designed and synthesized three AS ODNs (NP267, NP628, NP749) that were specific for the RNA binding region of nucleoprotein (NP) based on AIV structure. Results showed that all three AS ODNs could inhibit viral replication in MDCK cells. The NP628 showed the best antiviral effect of all through viral titers, quantitative RT-PCR and indirect immunofluorescence (IFA) assays. In addition, the liposome mediated NP628 could partially protect the mice from a lethal H5N1 influenza virus challenge. Moreover, the NP628 group had a lower viral titer and lung index in the infected mice when compared with the viral control. Our results showed that AS ODN targeting of the AIV NP gene could potently inhibit AIV H5N1 reproduction, thus, formulating a candidate for an emergent therapeutic drug for the pathogenic H5N1 influenza virus infection.     

Antisense oligonucleotides targeting the RNA binding region of the NP gene inhibit replication of highly pathogenic avian influenza virus H5N1

The H5N1 avian influenza virus (AIV) causes widespread infections in bird and human respiratory tracts, and vaccines and drug therapy are limited in their effectiveness. Recent studies of AIV structures have been published and provide new targets for designing antiviral drugs such as antisense oligonucleotides (AS ODNs), which effectively inhibit gene replication. In this study, we designed and synthesized three AS ODNs (NP267, NP628, NP749) that were specific for the RNA binding region of nucleoprotein (NP) based on AIV structure. Results showed that all three AS ODNs could inhibit viral replication in MDCK cells. The NP628 showed the best antiviral effect of all through viral titers, quantitative RT-PCR and indirect immunofluorescence (IFA) assays. In addition, the liposome mediated NP628 could partially protect the mice from a lethal H5N1 influenza virus challenge. Moreover, the NP628 group had a lower viral titer and lung index in the infected mice when compared with the viral control. Our results showed that AS ODN targeting of the AIV NP gene could potently inhibit AIV H5N1 reproduction, thus, formulating a candidate for an emergent therapeutic drug for the pathogenic H5N1 influenza virus infection.     

10种中成药体外抗流感病毒活性研究

流感是一种高发病率和高死亡率的上呼吸道传染病, 我国是流感高发区。国际上预防与治疗流感的主要措施是疫苗接种和抗病毒化学药物治疗。除此之外我国临床上还利用传统中药进行抗流感病毒治疗。本研究采用细胞病变 (CPE) 法, 对10种中成药进行体外抗流感病毒活性检测。厂家H生产的清热解毒口服液体外对A/广东罗湖/219/2006 (H1N1) 具有较强的抑制活性; 银黄口服液对A/汉防/359/95和A/粤防/243/72, 厂家G生产的清开灵口服液对A/济防/15/90, 厂家H生产的清热解毒口服液对A/济防/15/90、A/粤防/243/72和B/深圳/155/2005具有较强的抑制活性。     

Discovery of dihydro-alkyloxy-benzyl-oxopyrimidines as promising anti-influenza virus agents

A series of novel dihydro-alkyloxy-benzyl-oxopyrimidine derivatives were synthesized and evaluated for their activity against influenza virus in Madin-Darby canine kidney cells. Four dihydro-alkyloxy-benzyl-oxopyrimidine derivatives (4a1, 4a2, 4a3, and 4d1) showed potent activity against influenza virus. Among them, compound 4a3 was the most promising lead with broad activity against influenza A (antiviral EC(50) values of 9 and 18 μm for the A/H1N1 and A/H3N2 subtype, respectively) and influenza B viruses (EC(50) : 33 μm). The antiviral mechanism of action of these dihydro-alkyloxy-benzyl-oxopyrimidine derivatives must be quite different from that of the currently approved anti-influenza virus drugs that target the viral M2 or neuraminidase proteins. The dihydro-alkyloxy-benzyl-oxopyrimidine derivatives represent a new avenue for further optimization and development of novel anti-influenza virus agents.     

细胞基因工程重组人α1干扰素对7种流感病毒的抗病毒作用

目的：研究细胞基因工程人α干扰素（ｒｈＩＦＮ－α１）对体外７种流感病毒感染的ＭＤＣＫ细胞以及对甲型流感病毒鼠肺适应株ＰＲ８引起的小鼠肺炎的对抗作用。方法：接种７种病毒液（Ｈ１Ｎ１、Ｈ２Ｎ２,Ｈ３Ｎ３,Ｂ型,Ｃ型,Ａ１,Ｂ分离株）于ＭＤＣＫ细胞中,小鼠用ＰＲ８病毒液滴鼻,观察ｒｈＩＦＮ－α１的抗病毒作用。结果：ｒｈＩＦＮ－α１对７种病毒液的最小有效深度分别１２．５、２５,５０,１２。５,２５和１２。     

Docking study on chlorogenic acid as a potential H5N1 influenza A virus neuraminidase inhibitor

Docking simulation between chlorogenic acid and H5N1 influenza virus neuraminidase (NA) was performed and the binding free energies of the best pose and average for the best three different poses of H5N1 NA–chlorogenic acid complex are −9.71 and −9.27 kcal/mol, respectively, which is lower than those of H5N1 NA–oseltamivir complex (−7.13 and −6.39 kcal/mol) by using ArgusLab docking method. The hydrogen bonds could be formed between chlorogenic acid and the H5N1 NA amino acid residues Arg156 and Thr439. Arg152 from the 150-cavity makes polar contact with the –COOH group in chlorogenic acid. Chlorogenic acid could be a potential H5N1 influenza A virus NA inhibitor.     

Favipiravir (T-705), a novel viral RNA polymerase inhibitor

Favipiravir (T-705; 6-fluoro-3-hydroxy-2-pyrazinecarboxamide) is an antiviral drug that selectively inhibits the RNA-dependent RNA polymerase of influenza virus. It is phosphoribosylated by cellular enzymes to its active form, favipiravir-ribofuranosyl-5′-triphosphate (RTP). Its antiviral effect is attenuated by the addition of purine nucleic acids, indicating the viral RNA polymerase mistakenly recognizes favipiravir-RTP as a purine nucleotide. Favipiravir is active against a broad range of influenza viruses, including A(H1N1)pdm09, A(H5N1) and the recently emerged A(H7N9) avian virus. It also inhibits influenza strains resistant to current antiviral drugs, and shows a synergistic effect in combination with oseltamivir, thereby expanding influenza treatment options. A Phase III clinical evaluation of favipiravir for influenza therapy has been completed in Japan and two Phase II studies have been completed in the United States. In addition to its anti-influenza activity, favipiravir blocks the replication of many other RNA viruses, including arenaviruses (Junin, Machupo and Pichinde); phleboviruses (Rift Valley fever, sandfly fever and Punta Toro); hantaviruses (Maporal, Dobrava, and Prospect Hill); flaviviruses (yellow fever and West Nile); enteroviruses (polio- and rhinoviruses); an alphavirus, Western equine encephalitis virus; a paramyxovirus, respiratory syncytial virus; and noroviruses. With its unique mechanism of action and broad range of antiviral activity, favipiravir is a promising drug candidate for influenza and many other RNA viral diseases for which there are no approved therapies.     

芦丁对流感病毒的体外抑制作用及其机制研究

目的研究芦丁对流感病毒的体外抑制作用并探讨其机制。方法利用流感病毒感染MDCK细胞模型,观察芦丁对流感病毒的体外抑制作用;结合流感病毒感染前、感染同时及感染后加药的不同方式探索芦丁作用于流感病毒生命周期的具体阶段;采用荧光底物法考察芦丁对流感病毒神经氨酸酶的抑制作用。结果芦丁对A/Puerto Rico/8/1934(H1N1)、A/FM1/1/47(H1N1)、A/Human/Hubei/3/2005(H3N2)、A/Beijing/32/92(H3N2)4株流感病毒均具有体外抑制作用,其中对A/Puerto Rico/8/1934(H1N1)株的半数有效浓度(EC50)最小,选择指数(SI)最大,体外药效最好。芦丁在流感病毒感染后给药的效果最为明显,对流感病毒A/FM1/1/47(H1N1)的IC50最小,对神经氨酸酶活性抑制作用相对最好。结论芦丁抑制了流感病毒神经氨酸酶活性,具有较好的体外抗流感病毒作用。     

Arylazolyl(azinyl)thioacetanilide. Part 9: Synthesis and biological investigation of thiazolylthioacetamides derivatives as a novel class of potential antiviral agents

In continuation of our endeavor to develop new, potent, selective and less toxic antiviral agents, a novel series of 2-(2-amino/chloro-4-(2,4-dibromophenyl) thiazol-5-ylthio)acetamide derivatives was synthesized via an expeditious route and evaluated for their anti-HIV activities against wild-type virus and clinically relevant mutant strains, and for their anti-influenza virus activities against influenza A (H1N1 and H3N2) and influenza B in cellular assays. The selected active compounds were also assayed for their enzymic inhibitory activities. The results showed that some 2-chloro substituted thiazolylthioacetamide derivatives possessed potent activity against wild type HIV-1 and several key mutant strains (E138K, K103N, L100I) of HIV-1 in MT-4 cells with EC(50) values in micromolar range. Two 2-amino substituted thiazole derivatives 8a7 and 8a8 displayed significant potency against influenza A/H1N1 in MDCK cells with EC(50) values much lower than that of oseltamivir carboxylate, ribavirin, amantadine and rimantadine. Though the mechanism of actions is still unclear, these novel thiazolylthioacetamides might serve as original leads for further pharmacological investigations as potential therapeutic agents against HIV-1 or influenza virus.     

synthesis and preliminary biologic evaluation of 5-substituted-2-(4-substituted phenyl)-1,3-benzoxazoles as a novel class of influenza virus A inhibitors

The diversity-oriented chemistry synthesis together with the random screening approach has permitted the discovery and optimization of novel antiviral lead compounds. In this paper, a series of novel 5-substituted-2-(4-substituted phenyl)-1,3-benzoxazoles was synthesized and evaluated for their in vitro anti-influenza A virus and anti-influenza B virus activity. The activity was monitored by the MTS assay in the Madin-Darby canine kidney cells. Compound 7h showed excellent inhibitory activity and selective index against A/H3N2 (EC(50) = 37.03 μm, SI > 5), which were all higher than that of the reference drug oseltamivir (EC(50) > 59.00 μm, SI > 1). However, no compound displays inhibitory activity against influenza B virus.     

Patchouli alcohol: in vitro direct anti-influenza virus sesquiterpene in <Emphasis Type="Italic">Pogostemon cablin</Emphasis> Benth.

During the screening of anti-influenza virus substances from traditional herbal medicines, the methanol extract from the leaves of Pogostemon cablin Benth. showed potent in vitro antiviral activity (99.8% inhibition at a concentration of 10 μg/mL) against influenza virus A/PR/8/34 (H1N1). The anti-influenza virus principle was isolated from the hexane-soluble fraction, through solvent fractionation, repeated silica gel column chromatography, and reversed-phase HPLC. The major active principle was a volatile substance that was identified as a sesquiterpene, patchouli alcohol (1), on the basis of its spectral analyses. When anti-influenza virus activity against A/PR/8/34 was evaluated by the plaque forming assay, patchouli alcohol reduced the number of plaques by 75% at 2 μg/mL and 89% at 10 μg/mL. Patchouli alcohol showed dose-dependent anti-influenza virus activity, and its IC₅₀ value was estimated to be 2.635 μM. Although 11 different sesquiterpenes were tested for antiviral activity against influenza virus A/PR/8/34, no or negligible activity was observed except for patchouli alcohol. Patchouli alcohol did not show anti-influenza virus activity against A/Guizhou/54/89 (H3N2), but showed weak activity against B/Ibaraki/2/85 (IC₅₀ = 40.82 μM). Patchouli alcohol did not show inhibitory activity against influenza virus neuraminidase.     

Design, synthesis, and in vitro biological evaluation of 1H-1,2,3-triazole-4-carboxamide derivatives as new anti-influenza A agents targeting virus nucleoprotein

The influenza virus nucleoprotein (NP) is an emerging target for anti-influenza drug development. Nucleozin (1) and its closely related derivatives had been identified as NP inhibitors displaying anti-influenza activity. Utilizing 1 as a lead molecule, we successfully designed and synthesized a series of 1H-1,2,3-triazole-4-carboxamide derivatives as new anti-influenza A agents. One of the most potent compounds, 3b, inhibited the replication of various H3N2 and H1N1 influenza A virus strains with IC(50) values ranging from 0.5 to 4.6 μM. Compound 3b also strongly inhibited the replication of H5N1 (RG14), amantidine-resistant A/WSN/33 (H1N1), and oseltamivir-resistant A/WSN/1933 (H1N1, 274Y) virus strains with IC(50) values in sub-μM ranges. Further computational studies and mechanism investigation suggested that 3b might directly target influenza virus A nucleoprotein to inhibit its nuclear accumulation.     

Identification of novel virus inhibitors by influenza A virus specific reporter cell based screening

As influenza viruses have developed resistance towards current drugs, it is urgent to find potential novel antiviral inhibitors. Here we generated an influenza virus reporter cell line in which the luciferase gene was driven by the influenza virus promoter and screened a small compound library (NCI Diversity Set II). Ten compounds were identified to have inhibitory activity against influenza A virus H1N1. Among them, four compounds blocked influenza virus replication through inhibiting the activity of vRNP. The compound NSC 335506 inhibited HA-mediated membrane fusion. It showed the inhibitory activity against H1N1, H9N2 and H5N1 subtype but not H3N2. Our results demonstrated that influenza virus reporter cell is a very useful tool to identify novel inhibitors against influenza A virus.     

Effective small interfering RNAs targeting matrix and nucleocapsid protein gene inhibit influenza A virus replication in cells and mice

RNA interference (RNAi) is a powerful tool to silence gene expression. Small interfering RNA (siRNA)-induced RNA degradation has been recently used as an antivirus agent to inhibit specific virus replication. Here, we showed that several siRNAs specific for conserved regions of influenza virus matrix (M2) and nucleocapsid protein (NP) genes could effectively inhibit expression of the corresponding viral protein. We also evaluated the antiviral potential of these siRNAs targeting M2 and NP of H5N1 avian influenza virus (AIV), which are essential to viral replication. We investigated the inhibitory effect of M2-specific siRNAs and NP-specific siRNAs on influenza A virus (H5N1, H1N1 and H9N2) replication in Madin-Darby canine kidney (MDCK) cells and BALB/c mice. The results showed that treatment with these siRNAs could specifically inhibit influenza A virus replication in MDCK cells (0.51-1.63 TCID(50) reduction in virus titers), and delivery of pS-M48 and pS-NP1383 significantly reduced lung virus titers in the infected mice (16-50-fold reduction in lung virus titers) and partially protected the mice from lethal influenza virus challenge (a survival rate of 4/8 for H1N1 virus-infected mice and 2/8 for H5N1 virus infected mice). Moreover, the treatment of pS-M48 and pS-NP1383 could suppress replication of different subtypes of influenza A viruses, including a H5N1 highly pathogenic avian isolate strain. The results provided a basis for further development of siRNA for prophylaxis and therapy of influenza virus infection in humans and animals.     

Chemo-enzymatic synthesis of 5-substituted ribavirin analogs: Unexpected cooperative effect in the interaction of 5-alkyloxymethyl 1,2,4-triazol-3-carboxamides with E. coli purine nucleoside phosphorylase active site

A series of 5-alkyl/aryl-oxymethyl-ribavirin analogs was synthesized. Surprisingly, ability of E. coli purine nucleoside phosphorylase (PNP) to synthesize ribonucleosides and 2′-deoxyribonucleosides having structurally diverse alkyl(aryl)oxymethyl substituents at the 5 position of 1,2,4-triazol-3-carboxamide has been discovered. It has been shown that the enzymatic synthesis of 2′-deoxyribonucleosides proceeds with better conversion and is faster (up to 50 h) than the synthesis of ribonucleosides (more than 300 h). Therefore, ribonucleosides were synthesized by chemical glycosylation of base triazoles by 2,3,4,5-tetra-O-acetyl-D-ribose in the presence of bis(4-nitrophenyl) phosphate. 2′-Deoxyribonucleosides were synthesized by the transglycosylation reaction with E. coli PNP. For the first time, based on the kinetic parameters of the 2′-deoxyribonucleosides synthesis process, the positive cooperativity effect of wild type PNP active sites was discovered. The antiviral activity of nucleosides has been tested against herpes simplex virus type 1 (HSV-1) and influenza virus H5N1. The cytotoxicity and antiviral activity of the synthesized nucleosides differ, and it is impossible to draw an unambiguous conclusion about the structure-activity correlation.     

Genotypic and phenotypic resistance of pandemic A/H1N1 influenza viruses circulating in Germany

In response to the rapid global spread of an antigenically novel A/H1N1 influenza virus in 2009, the World Heath Organization (WHO) recommended surveillance and monitoring for antiviral resistance of influenza viruses. We designed and evaluated pyrosequencing (PSQ)-based genotypic assays for high-throughput analysis of the susceptibility of pandemic A/H1N1 influenza viruses to neuraminidase (NA) inhibitors. A total of 1570 samples circulating in Germany between April 2009 and April 2010 were tested for determination of molecular markers of resistance to the NA inhibitors oseltamivir and zanamivir, and 635 of them were evaluated by phenotypic fluorescence-based assay with MUNANA substrate. Eight (0.5%) viruses were resistant to oseltamivir due to the H274Y NA substitution (N2 numbering). Six of these oseltamivir-resistant cases were treatment-related; four of them were selected in immunocompromised patients, two in patients suffered from chronic diseases. The two remaining oseltamivir-resistant viruses seem to have evolved in the absence of drug treatment and were isolated from immunocompetent healthy patients. All tested A/H1N1 pandemic viruses were sensitive to zanamivir. In addition, analysis of 1011 pandemic A/H1N1 virus samples by a PSQ-based assay according to the WHO protocol revealed the presence of mutation S31N in the M2 protein that conferred resistance to M2 ion channel inhibitors. Our data demonstrate a low incidence of oseltamivir-resistant pandemic A/H1N1 influenza variants isolated under drug selection pressure as well as community-acquired or naturally evolving viruses.     

Easily hydrolyzable, water-soluble derivatives of (+/-)-alpha-5-[1-(indol-3-yl)ethyl]-2-methylamino-delta2-thiazoline-4-one, a novel antiviral compound.

The preparation of a series of indole N-acyl and N-carbamic esters of (+/-)-alpha-5-[1-(indol-3-yl)ethyl]-2-methylamino-delta2-thiazolin-4-one (1) is reported. These derivatives were synthesized as potential water-soluble precursors of the antiviral thiazolinone 1, for evaluation by intranasal administration against influenza and other respiratory infections caused by viruses. Salts of the basic carbamic esters (16--19) possess the required water solubility, undergo rapid hydrolysis and decarboxylation at pH values greater than 6, and have high activity against influenza A2 and Coxsackie B1 viruses in vitro. In influenza A2 infected ferrets a representative ester (16) reduced the severity and duration of disease symptoms and reduced nasal wash virus titres but caused local irritancy.     

Spontaneous Pneumomediastinum,Pneumopericardium and Pneumorrhachis as potential complications of 2009 pandemic influenza A (H1N1) virus infection in healthy children

We report on two cases of spontaneous pneumomediastinum and pneumopericardium, in one case associated with pneumorrhachis, occurring in two children suffering from the novel influenza H1N1 virus infection. At the admission both children presented with fever, violent dry cough, dyspnea and tachypnea. Radiological studies showed sizeable pneumomediastinum and pneumopericardium in both patients. One of the patients also a pneumorrachis. Children were initially treated by intravenous broad-spectrum antibiotics, antipyretics and a cough sedative. Oral Oseltamivir (60 mg twice daily for 5 days) was administered after the diagnosis of influenza A (H1N1) virus infection. Patients’ clinical condition quickly improved and children were discharged with a partial resolution of their radiological findings. Although these conditions are usually self-limiting and without respiratory or systemic consequences, their prompt recognition in children with H1N1 influenza virus infection is essential to establish fast and adequate therapy mainly related to the control of cough and the commencement of antiviral treatment.