You are here:  > Browse Articles

Pointer

Small molecule inhibitors of West Nile virus

Samia A Elseginy1, Alberto Massarotti2, Galal AM Nawwar3, Kamilia M Amin4, Andrea Brancale1,*

1School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
2Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale ‘A Avogadro’, Novara, Italy
3Department of Chemical Industries, National Research Centre, Giza, Egypt
4Department of Therapeutic Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt

*Corresponding author e-mail: brancalea@cardiff.ac.uk

Citation: Antiviral Chemistry & Chemotherapy 2014; 23:179-187
doi: 10.3851/IMP2581

Date accepted: 09 April 2013
Date published online: 02 May 2013

Copyright (c) 2014 International Medical Press, all rights reserved.

Abstract

West Nile virus (WNV) is a human pathogen which is rapidly expanding worldwide. It is a member of the Flavivirus genus and it is transmitted by mosquitos between its avian hosts and occasionally in mammalian hosts. In humans the infection is often asymptomatic, however, the most severe cases result in encephalitis or meningitis. Approximately 10% of cases of neuroinvasive disease are fatal. To date there is no effective human vaccine or effective antiviral therapy available to treat WNV infections. For this reason, research in this field is rapidly growing. In this article we will review the latest efforts in the design and development of novel WNV inhibitors from a medicinal chemistry point of view, highlighting challenges and opportunities for the researchers working in this field.

Introduction

West Nile virus (WNV) is a member of the genus Flavivirus, a group of enveloped viruses with a positive-sense RNA genome. This genus contains many important human pathogens (for example, dengue, Japanese encephalitis and yellow fever viruses), which together infect millions of people worldwide and are the cause of tens of thousands of fatalities annually [1]. WNV has been reported in dead or dying birds of at least 326 species [2]. In humans, it was first isolated in the West Nile province of Uganda in 1937 from the blood of a woman suffering from a mild febrile illness [3].

WNV is an emerging human pathogen with an expanding geographical distribution, spreading rapidly in recent years throughout North America [4,5]. It has been the cause of an increasing number of human infections with associated severe disease and fatalities. WNV is transmitted by mosquitoes within its avian host populations and to incidental vertebrate hosts, including humans and horses. Infection in humans is generally asymptomatic or causes a mild febrile disease in about 20–30% of cases. The most severe cases of WNV infection result in encephalitis or meningitis. Around 10% of cases of neuroinvasive disease are fatal and the survivors may suffer from long-term cognitive and neurological impairment [6]. The most important risk factors for these more serious complications are aging and a compromised immune system [7]. Although vaccines are available against some flaviviruses, unfortunately there is no effective human vaccine or effective antiviral therapy available for WNV, indeed, their development remains a high priority for the World Health Organization [8,9].

The present review will concentrate primarily on the medicinal chemistry effort in the development of potential inhibitors of WNV. Other aspects of flavivirus infections, including WNV, are covered excellently elsewhere [1012].

West Nile virus protein targets

WNV contains a single-stranded positive sense RNA genome (Figure 1), which encodes three structural proteins, capsid, pre-membrane and envelope (C, prM and E), and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5). Non-structural protein 1 (NS1) has been implicated in host immune response evasion, however the function of NS2A is poorly defined. NS2B functions as a cofactor protein in the protease function of NS3, which is a multifunctional protein, consisting of the N-terminal protease domain and C-terminal helicase, nucleoside triphosphatase and RNA triphosphatase activities [13]. The function of NS4A is a matter of debate and NS4B membrane protein is thought to anchor and target the replication complex to the endoplasmic reticulum (ER) membrane. NS5 is the largest of the non-structural proteins and it contains a classic RNA-dependent RNA polymerase domain as well as methyltransferase and guanylyltransferase domains for mRNA capping necessary for viruses that replicate their mRNA in the cytoplasm [14].

-
Figure 1.
Figure 1. The RNA genome of West Nile virus

E protein inhibitors

Wang et al. [15] from Novartis performed a virtual screening using a 586,000 compound library (a subset of the corporate compound collection) revealing a hydrophobic pocket in the DENV-2 strain S1 envelope protein. The top-ranked compounds were also docked in the crystal structure of the WNV E protein [16,17], which contains a hydrophobic pocket that is presumably important for low-pH mediated membrane fusion. After performing a high-throughput docking within this hydrophobic pocket, compound 1 (Figure 2) was evaluated in cell-based assays showing a 50% effective concentration (EC50) of 0.564 ±0.17 µM [15].

-
Figure 2.
Figure 2. Chemical structures of West Nile virus E protein inhibitors

An in silico screening of the Maybridge chemical database was performed on the dengue E protein structure. The biological evaluation of the most promising compounds obtained from the computer-based simulation revealed two hit structures with low micromolar antiviral activity against dengue virus. Interestingly, one of these compounds (2) also has antiviral activity against both WNV and yellow fever virus [18].

NS2B/NS3 protease inhibitors

Historically, WNV NS3 protease and the NS2B cofactor have always been indicated as attractive targets for drug development, due to their essential catalytic activity [19,20]. The WNV NS2B-NS3 is a serine-like protease, important for viral replication. Viral proteases in general are proving to be successful antiviral targets (for example, for HIV) and inhibitors of serine protease in particular look promising for treating flaviviruses (for example, hepatitis C [21]). Several homology models for WNV NS2B/NS3 protease were reported [2224], unfortunately all these structures were significantly different from the subsequent crystal structures of the active protease (PDB id: 2FP7 [25], PDB id: 2IJO [26]) because of the unusual binding mode of the NS2B cofactor which encircles and stabilizes the protease structure [27].

Peptide-like inhibitors

A common strategy used for the inhibition of the NS2B/NS3 protease involved covalent inhibitors that compete with the substrate for the catalytic site. Such peptide-based inhibitors have their C-terminal carboxyl group chemically modified into reactive electrophilic ‘warheads’. A popular warhead is the aldehyde functional group and peptide-aldehydes have been shown to inhibit the WNV NS2B/NS3 protease at submicromolar concentrations [28]. In this study peptidomimetics containing a P1 decarboxylated arginine (agmatine) compound (4-phenyl-phenacetyl-Lys-Lys-agmatine) showed potent inhibition of the WNV protease (50% inhibitory concentration [IC50] 4.7 ±1.2 µM). This inhibitor does not bind covalently to the catalytic serine in the active site but instead competes with the natural substrate for the active site with a binding affinity of Ki 2.05 ±0.13 µM. Selectivity for WNV NS2B/NS3 protease was demonstrated using thrombin, a mammalian serine protease involved in blood clotting that is selective for peptide substrates with a P1 Arg. The compound did not inhibit thrombin at a concentration of 100 µM, showing a good selectivity towards the WNV NS2B/NS3 protease [29]. In 2013 the same research group has reported 37 novel agmatine dipeptides [30]. The most potent inhibitor displayed an IC50 of 2.6 ±0.3 μM against the WNV NS2B/NS3 protease, a twofold improvement over the inhibitor described previously.

Recently, a series of new substrate analogues of NS2B/NS3 protease based on trans-(4-guanidino)cyclohexylmethylamide (GCMA) were identified. These GCMA inhibitors are stable, readily accessible and have a better selectivity profile than the previously described agmatine analogues. Furthermore, they possess negligible affinity for the trypsin-like serine proteases thrombin, factor Xa, and matriptase. A crystal structure in complex with the WNV protease was determined for one of the most potent inhibitors, 3,4-dichlorophenylacetyl-Lys-Lys-GCMA (Ki=0.13 μM) [31].

It should be noted that, despite their potency, warhead peptidomimetics have several undesirable characteristics, including lack of selectivity over other trypsin-like proteases due to their high reactivity and low chemical stability, limiting their potential for drug development [32].

Non-peptide inhibitors

Recently, different non-peptidomimetic inhibitors have been reported in the literature. Compound 3 (Figure 3) has been identified by automatic fragment-based docking of about 12,000 compounds and is able to inhibit WNV protease NS3 with an IC50 of 183 µM [33].

-
Figure 3.
Figure 3. Chemical structures of West Nile virus NS2B/NS3 protease inhibitors

A more potent compound, the sultam thiourea TYT-1 (4), was identified by screening a 3,500 molecule library in a cell-based assay that measured the compound’s ability to protect the cells from WNV-induced cytopathic effects. Compound 4 proved to be one of the most potent WNV NS3 inhibitors reported to date (IC50=0.7 μM) [34].

Exploratory studies, using a combinatorial approach based on the 1-oxo-1,2,3,4-tetrahydroisoquinoline scaffold, have led to the identification of a hit (5), which inhibited WNV protease at (IC50=30 µM) [35]. The design rationale for this compound is based on the observation that molecules containing the aforementioned scaffold are substrates of chymotrypsin, hence a problem of selectivity might arise for compound 5 and related analogues.

Compounds 6 and 7, two 8-hydroxyquinoline (8-HQ) derivatives, exhibited inhibition of WNV protease in vitro, with a Ki of 3.2 ±0.3 µM and 3.4 ±0.3 µM, respectively [36]. In further studies, 15 compounds having 8-HQ scaffold were biologically tested as WNV protease inhibitors and compound 7 proved to be the most potent of the series with an IC50 of 2.01 ±0.08 µM. It is noteworthy that the compound containing the naphthalene-1-ol moiety instead of the 8-HQ group showed a significantly reduced activity, underlying the importance of this heterocyclic ring for the inhibition of WNV NS2B/NS3 protease by this class of compounds [37].

The aminobenzamide scaffold was also utilized in the synthesis of a series of structurally diverse meta and para-substituted derivatives [38]. The four analogues that exhibited activity against WNV protease, all have a (pehnoxy)phenyl group present in the meta or para position. The most potent aminobenzamide derivative is compound 8, which showed a low micromolar NS3/NS2B protease inhibition (IC50=5.5 ±0.08 μM). These compounds also showed activity against the DENV protease.

Recently, Tiew et al. [39] have identified a series of triazolic compounds active on both dengue virus and WNV NS2B/NS3 protease. The compounds were obtained from the benz[d]isothiazol-3(2H)-one scaffold using a click-chemistry derived library. The most interesting molecules (9 and 10) display weak inhibitory activity toward the NS2B-NS3 protease.

3-Aryl-2-cyanoacrylamides were identified as a new class of nitrile-containing inhibitors of the NS3/NS2B protease by Nitsche et al. [40]. The most relevant structural features required for activity are: a para-substituted aromatic system with high electron density, an amide or acid residue and a planar geometry. Consequently, the most active molecule was the hydroxyl derivative (11), with a Ki of 44.6 μM.

The 5-amino-1-(phenyl)sulfonyl-pyrazol-3-yl based inhibitors seem to interfere with the binding of the NS2B cofactor with the NS3 protease. The hit compounds (12 and 13), which showed a sub-micromolar activity, were obtained by high-throughput screening (HTS), using the National Institutes of Health’s 65,000 compound library [41]. However, these derivatives were rapidly hydrolyzed in an aqueous buffer (pH 8) to the corresponding pyrazol-3-ol and, for this reason, the authors designed and synthesized a new series of analogues with improved chemical stability. The two ester isosteres derivative, compound 14, which contains an alkene group, and compound 15, an amide analogue, although less potent than the original hits (IC50 of 13.8 μM and 16.0 μM, respectively), are highly stable inhibitors of WNV NS2B/NS3 proteinase with a degradation time of 13 and 96 h, respectively [42].

NS5 – RNA-dependent RNA polymerase inhibitors

Puig-Basagoiti et al. [43] reported the results of an HTS study, which was performed by screening nearly 100,000 compounds in WNV replicon assay. From this exercise, five novel inhibitors have been identified with EC50 values of <10μM and therapeutic index (TI) values of >10. Viral titre reduction assays, using various flaviviruses and non-flaviviruses, showed that the compounds have distinct antiviral spectra. One compound (16, Figure 4) suppresses both viral translation and RNA synthesis (EC50=12 μM), whereas the other four compounds suppress only RNA synthesis. Examination of the antiviral spectrum revealed an unspecific profile for compounds 1719 with an EC50 of 0.2, 8 and 0.7 μM, respectively. Compound 20 appeared to be the only one able to block RNA synthesis by selective inhibition of WNV NS5 (EC50=14 μM).

-
Figure 4.
Figure 4. Chemical structures of West Nile virus NS5 inhibitors

NTPase/helicase inhibitors

Compound 21 (Figure 5) exhibited helicase inhibitory activity against WNV NTPase/helicase with an IC50 value of 3–10 μg/ml when an RNA substrate was employed. However, no inhibition could be detected when the same experiment was repeated using a DNA substrate [44]. Interestingly, compound 22, the ribose analogue of compound 21, showed activity against NTPase/helicase of WNV when DNA substrate was employed (IC50=23 μM), but no inhibition could be detected when the same experiment was repeated using an RNA substrate [45]. As flaviviridae are RNA viruses, the observed results are surprising, especially considering that the 2-deoxyribose analogue 21 has shown activity against the NTPase/helicase of WNV only when using an RNA substrate. The significance and implications of these results are not clear at the moment. There are several reports that demonstrate non-covalent, tight-binding interactions of analogues of nucleobases, nucleosides and nucleotides, to major or minor grooves of DNA or RNA double helices [46,47]. However, preliminary studies show that compound 22 does not form a tight complex with either an RNA or a DNA substrate, suggesting that its mechanism of action may involve direct interaction with the enzyme. Related ribose analogues 23 and 24 were also found to inhibit the WNV NTPase/helicase with an IC50 of approximately 50 and 3 μM, respectively [48,49].

-
Figure 5.
Figure 5. Chemical structures of West Nile virus NTPase/helicase inhibitors

Other inhibitors

Many investigators have noted the broad antiviral properties of ribavirin (25, Figure 6) [50], currently a mainstay of therapy in combination with interferon-α for the treatment of HCV. Although ribavirin shows some activity against WNV in vitro (EC50 approximately 200 μM), in vivo studies have been less promising, with reports of ribavirin treatment increasing mortality in Syrian golden hamsters infected with WNV New York strain CDC996625 [51].

-
Figure 6.
Figure 6. Chemical structures of inhibitors with a non-specific or unknown mode of action

A recent paper has reported weak anti-WNV activity of the tetracycline antibiotic minocycline (26) in a cytopathic effect assay in Vero cells, with an IC50 of approximately 20 μM [52]. Olivo et al. [53] have also disclosed a series of aminoquinoline compounds that possess antiviral activity against a range of viruses, including WNV, although no details on the mechanism of action have been provided. Compound 27 has activity against a DENV-2 sub-genomic replicon cell line with EC50 5 μM and against a WNV sub-genomic replicon cell line with an EC50 of 1.9 μM [53].

Conclusions

WNV virus is rapidly spreading worldwide and, despite the possibility that viral infection could lead to severe encephalitis, neither a vaccine nor an antiviral therapy is currently available. In this paper we have provided a summary of the current medicinal chemistry efforts in identifying small molecule inhibitors of WNV. Indeed, several interesting leads are now appearing in the literature. However, we believe there are still areas that require a more intensive investigation. In particular, it is easy to notice that researchers have been focusing their attention mainly on the NS3 protease, whereas, in comparison, little has been reported on the inhibition of the NS5 polymerase and methyltransferase. Interestingly, several crystal structures of the latter have become available in the last few years (Table 1) and they could be used in virtual screening simulations or other structure-based drug design methodologies. For this reason, it is possible to foresee an increase in interest around this target in the near future. It should be mentioned that the research around the development of antiviral compounds active against dengue virus is at a more advanced stage compared to WNV [54,55]. Given the close similarity between these two viruses, it is likely that some of the anti-dengue molecules reported in the literature could also be useful against WNV. Indeed, several of the compounds reported in this review show activity against both viruses. Furthermore, the knowledge and the insight gained with the exciting development of novel anti-HCV agents could also be used as a foundation for the identification of suitable WNV inhibitors. Finally, it should not be overlooked that the most severe cases affect the central nervous system, thus any future antiviral therapy agents should be able to cross the blood–brain barrier. This clearly represents one of the biggest challenges for the researchers in the field.

-
Table 1.  Crystallographic structures of West Nile virus proteins available in the Protein Data Bank
Table 1. Crystallographic structures of West Nile virus proteins available in the Protein Data Bank

Acknowledgements

The authors would like to acknowledge the Egyptian National Research Centre and the Egyptian Higher Education Ministry for the support to SAE.

Disclosure statement

The authors declare no competing interests.

References

-
1. Gould LH, Fikrig E. West Nile virus: a growing concern? J Clin Invest 2004; 113: 1102-1107. Medline doi:10.1172/JCI21623
-
2. The CDC database. (Accessed 25 February 2014. Updated 7 June 2013.) Available from http://www.cdc.gov/ncidod/dvbid/westnile/birds&mammals.htm.
-
3. Smithburn KC, Hughes TP, Burke AW, Paul JH. A neurotropic virus isolated from the blood of a native of Uganda. Am J Trop Med Hyg 1940; s1–20:471–492.
-
4. Mackenzie JS, Gubler DJ, Petersen LR. Emerging flaviviruses: the spread and resurgence of Japanese encephalitis, West Nile and dengue viruses. Nat Med 2004; 10: S98-S109. Medline doi:10.1038/nm1144
-
5. Komar N, Clark GG. West Nile virus activity in Latin America and the Caribbean. Rev Panam Salud Publica 2006; 19: 112-117. Medline doi:10.1590/S1020-49892006000200006
-
6. Davis LE, DeBiasi R, Goade DE, et al. West Nile virus neuroinvasive disease. Ann Neurol 2006; 60: 286-300. Medline doi:10.1002/ana.20959
-
7. Petersen LR, Marfin AA. West Nile virus: a primer for the clinician. Ann Intern Med 2002; 137: 173-179. Medline doi:10.7326/0003-4819-137-3-200208060-00009
-
8. Pugachev KV, Guirakhoo F, Monath TP. New developments in flavivirus vaccines with special attention to yellow fever. Curr Opin Infect Dis 2005; 18: 387-394. Medline doi:10.1097/01.qco.0000178823.28585.ad
-
9. De Filette M, Ulbert S, Diamond M, Sanders NN. Recent progress in West Nile virus diagnosis and vaccination. Vet Res 2012; 43: 16 Medline doi:10.1186/1297-9716-43-16
-
10. Bollati M, Alvarez K, Assenberg R, et al. Structure and functionality in flavivirus NS-proteins: perspectives for drug design. Antiviral Res 2010; 87: 125-148. Medline doi:10.1016/j.antiviral.2009.11.009
-
11. Parkinson T, Pryde DC. Small molecule drug discovery for dengue and West Nile viruses: applying experience from hepatitis C virus. Future Med Chem 2010; 2: 1181-1203. Medline doi:10.4155/fmc.10.195
-
12. Botting C, Kuhn RJ. Novel approaches to flavivirus drug discovery. Expert Opin Drug Discov 2012; 7: 417-428. Medline doi:10.1517/17460441.2012.673579
-
13. Gorbalenya AE, Donchenko AP, Koonin EV, Blinov VM. N-terminal domains of putative helicases of flavi- and pestiviruses may be serine proteases. Nucleic Acids Res 1989; 17: 3889-3897. Medline doi:10.1093/nar/17.10.3889
-
14. Brinton MA. The molecular biology of West Nile virus: a new invader of the western hemisphere. Annu Rev Microbiol 2002; 56: 371-402. Medline doi:10.1146/annurev.micro.56.012302.160654
-
15. Wang QY, Patel SJ, Vangrevelinghe E, et al. A small-molecule dengue virus entry inhibitor. Antimicrob Agents Chemother 2009; 53: 1823-1831. Medline doi:10.1128/AAC.01148-08
-
16. Kanai R, Kar K, Anthony K, et al. Crystal structure of West Nile virus envelope glycoprotein reveals viral surface epitopes. J Virol 2006; 80: 11000-11008. Medline doi:10.1128/JVI.01735-06
-
17. Nybakken GE, Nelson CA, Chen BR, Diamond MS, Fremont DH. Crystal structure of the West Nile virus envelope glycoprotein. J Virol 2006; 80: 11467-11474. Medline doi:10.1128/JVI.01125-06
-
18. Kampmann T, Yennamalli R, Campbell P, et al. In silico screening of small molecule libraries using the dengue virus envelope E protein has identified compounds with antiviral activity against multiple flaviviruses. Antiviral Res 2009; 84: 234-241. Medline doi:10.1016/j.antiviral.2009.09.007
-
19. Chambers TJ, Grakoui A, Rice CM. Processing of the yellow fever virus nonstructural polyprotein: a catalytically active NS3 proteinase domain and NS2B are required for cleavages at dibasic sites. J Virol 1991; 65: 6042-6050. Medline
-
20. Falgout B, Pethel M, Zhang YM, Lai CJ. Both nonstructural proteins NS2B and NS3 are required for the proteolytic processing of dengue virus nonstructural proteins. J Virol 1991; 65: 2467-2475. Medline
-
21. Abbenante G, Fairlie DP. Protease inhibitors in the clinic. Med Chem 2005; 1: 71-104. Medline doi:10.2174/1573406053402569
-
22. Nall TA, Chappell KJ, Stoermer MJ, et al. Enzymatic characterization and homology model of a catalytically active recombinant West Nile virus NS3 protease. J Biol Chem 2004; 279: 48535-48542. Medline doi:10.1074/jbc.M406810200
-
23. Ganesh VK, Muller N, Judge K, Luan CH, Padmanabhan R, Murthy KH. Identification and characterization of nonsubstrate based inhibitors of the essential dengue and West Nile virus proteases. Bioorg Med Chem 2005; 13: 257-264. Medline doi:10.1016/j.bmc.2004.09.036
-
24. Zhou H, Singh NJ, Kim KS. Homology modeling and molecular dynamics study of West Nile virus NS3 protease: a molecular basis for the catalytic activity increased by the NS2B cofactor. Proteins 2006; 65: 692-701. Medline doi:10.1002/prot.21129
-
25. Erbel P, Schiering N, D’Arcy A, et al. Structural basis for the activation of flaviviral NS3 proteases from dengue and West Nile virus. Nat Struct Mol Biol 2006; 13: 372-373. Medline doi:10.1038/nsmb1073
-
26. Aleshin AE, Shiryaev SA, Strongin AY, Liddington RC. Structural evidence for regulation and specificity of flaviviral proteases and evolution of the Flaviviridae fold. Protein Sci 2007; 16: 795-806. Medline doi:10.1110/ps.072753207
-
27. D’Arcy A, Chaillet M, Schiering N, et al. Purification and crystallization of dengue and West Nile virus NS2B-NS3 complexes. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62: 157-162. Medline doi:10.1107/S1744309106001199
-
28. Stoermer MJ, Chappell KJ, Liebscher S, et al. Potent cationic inhibitors of West Nile virus NS2B/NS3 protease with serum stability, cell permeability and antiviral activity. J Med Chem 2008; 51: 5714-5721. Medline doi:10.1021/jm800503y
-
29. Lim HA, Joy J, Hill J, San Brian Chia C. Novel agmatine and agmatine-like peptidomimetic inhibitors of the West Nile virus NS2B/NS3 serine protease. Eur J Med Chem 2011; 46: 3130-3134. Medline doi:10.1016/j.ejmech.2011.04.055
-
30. Lim HA, Ang MJ, Joy J, et al. Novel agmatine dipeptide inhibitors against the West Nile virus NS2B/NS3 protease: A P3 and N-cap optimization study. Eur J Med Chem 2013; 62: 199-205. Medline doi:10.1016/j.ejmech.2012.12.043
-
31. Hammamy MZ, Haase C, Hammami M, Hilgenfeld R, Steinmetzer T. Development and characterization of new peptidomimetic inhibitors of the West Nile virus NS2B-NS3 protease. ChemMedChem 2013; 8: 231-241. Medline doi:10.1002/cmdc.201200497
-
32. Becker GL, Sielaff F, Than ME, et al. Potent inhibitors of furin and furin-like proprotein convertases containing decarboxylated P1 arginine mimetics. J Med Chem 2010; 53: 1067-1075. Medline doi:10.1021/jm9012455
-
33. Ekonomiuk D, Su XC, Ozawa K, et al. Discovery of a non-peptidic inhibitor of west nile virus NS3 protease by high-throughput docking. PLoS Negl Trop Dis 2009; 3: e356 Medline doi:10.1371/journal.pntd.0000356
-
34. Barklis E, Still A, Sabri MI, et al. Sultam thiourea inhibition of West Nile virus. Antimicrob Agents Chemother 2007; 51: 2642-2645. Medline doi:10.1128/AAC.00007-07
-
35. Dou D, Viwanathan P, Li Y, et al. Design, synthesis, and in vitro evaluation of potential West Nile virus protease inhibitors based on the 1-oxo-1,2,3,4-tetrahydroisoquinoline and 1-oxo-1,2-dihydroisoquinoline scaffolds. J Comb Chem 2010; 12: 836-843. Medline doi:10.1021/cc100091h
-
36. Mueller NH, Pattabiraman N, Ansarah-Sobrinho C, Viswanathan P, Pierson TC, Padmanabhan R. Identification and biochemical characterization of small-molecule inhibitors of West Nile virus serine protease by a high-throughput screen. Antimicrob Agents Chemother 2008; 52: 3385-3393. Medline doi:10.1128/AAC.01508-07
-
37. Ezgimen M, Lai H, Mueller NH, et al. Characterization of the 8-hydroxyquinoline scaffold for inhibitors of West Nile virus serine protease. Antiviral Res 2012; 94: 18-24. Medline doi:10.1016/j.antiviral.2012.02.003
-
38. Aravapalli S, Lai H, Teramoto T, et al. Inhibitors of dengue virus and West Nile virus proteases based on the aminobenzamide scaffold. Bioorg Med Chem 2012; 20: 4140-4148. Medline doi:10.1016/j.bmc.2012.04.055
-
39. Tiew KC, Dou D, Teramoto T, et al. Inhibition of dengue virus and West Nile virus proteases by click chemistry-derived benz[d]isothiazol-3(2H)-one derivatives. Bioorg Med Chem 2012; 20: 1213-1221. Medline doi:10.1016/j.bmc.2011.12.047
-
40. Nitsche C, Steuer C, Klein CD. Arylcyanoacrylamides as inhibitors of the dengue and West Nile virus proteases. Bioorg Med Chem 2011; 19: 7318-7337. Medline doi:10.1016/j.bmc.2011.10.061
-
41. Johnston PA, Phillips J, Shun TY, et al. HTS identifies novel and specific uncompetitive inhibitors of the two-component NS2B-NS3 proteinase of West Nile virus. Assay Drug Dev Technol 2007; 5: 737-750. Medline doi:10.1089/adt.2007.101
-
42. Sidique S, Shiryaev SA, Ratnikov BI, et al. Structure-activity relationship and improved hydrolytic stability of pyrazole derivatives that are allosteric inhibitors of West Nile virus NS2B-NS3 proteinase. Bioorg Med Chem Lett 2009; 19: 5773-5777. Medline doi:10.1016/j.bmcl.2009.07.150
-
43. Puig-Basagoiti F, Qing M, Dong H, et al. Identification and characterization of inhibitors of West Nile virus. Antiviral Res 2009; 83: 71-79. Medline doi:10.1016/j.antiviral.2009.03.005
-
44. Ujjinamatada RK, Agasimundin YS, Zhang P, et al. A novel imidazole nucleoside containing a diaminodihydro-S-triazine as a substituent: inhibitory activity against the West Nile virus NTPase/helicase. Nucleosides Nucleotides Nucleic Acids 2005; 24: 1775-1788. Medline doi:10.1080/15257770500267063
-
45. Ujjinamatada RK, Baier A, Borowski P, Hosmane RS. An analogue of AICAR with dual inhibitory activity against WNV and HCV NTPase/helicase: synthesis and in vitro screening of 4-carbamoyl-5-(4,6-diamino-2,5-dihydro-1,3,5-triazin-2-yl)imidazole-1-beta-D-ribo furanoside. Bioorg Med Chem Lett 2007; 17: 2285-2288. Medline doi:10.1016/j.bmcl.2007.01.074
-
46. Marsch GA, Ward RL, Colvin M, Turteltaub KW. Non-covalent DNA groove-binding by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine. Nucleic Acids Res 1994; 22: 5408-5415. Medline doi:10.1093/nar/22.24.5408
-
47. Morales JC, Kool ET. Functional hydrogen-bonding map of the minor groove binding tracks of six DNA polymerases. Biochemistry 2000; 39: 12979-12988. Medline doi:10.1021/bi001578o
-
48. Borowski P, Lang M, Haag A, et al. Characterization of imidazo[4,5-d]pyridazine nucleosides as modulators of unwinding reaction mediated by West Nile virus nucleoside triphosphatase/helicase: evidence for activity on the level of substrate and/or enzyme. Antimicrob Agents Chemother 2002; 46: 1231-1239. Medline doi:10.1128/AAC.46.5.1231-1239.2002
-
49. Borowski P, Deinert J, Schalinski S, et al. Halogenated benzimidazoles and benzotriazoles as inhibitors of the NTPase/helicase activities of hepatitis C and related viruses. Eur J Biochem 2003; 270: 1645-1653. Medline doi:10.1046/j.1432-1033.2003.03540.x
-
50. Sidwell RW, Huffman JH, Khare GP, Allen LB, Witkowski JT, Robins RK. Broad-spectrum antiviral activity of Virazole: 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide. Science 1972; 177: 705-706. Medline doi:10.1126/science.177.4050.705
-
51. Morrey JD, Day CW, Julander JG, Blatt LM, Smee DF, Sidwell RW. Effect of interferon-alpha and interferon-inducers on West Nile virus in mouse and hamster animal models. Antivir Chem Chemother 2004; 15: 101-109. Medline
-
52. Michaelis M, Kleinschmidt MC, Doerr HW, Cinatl J. Minocycline inhibits West Nile virus replication and apoptosis in human neuronal cells. J Antimicrob Chemother 2007; 60: 981-986. Medline doi:10.1093/jac/dkm307
-
53. Olivo PD, Buscher BA, Dyall J, et al. 4-Aminoquinoline compounds for treating virus-related conditions. United States patent WO2006121767A2. 2006 November 16.
-
54. Noble CG, Chen YL, Dong H, et al. Strategies for development of dengue virus inhibitors. Antiviral Res 2010; 85: 450-462. Medline doi:10.1016/j.antiviral.2009.12.011
-
55. Noble CG, Shi PY. Structural biology of dengue virus enzymes: towards rational design of therapeutics. Antiviral Res 2012; 96: 115-126. Medline doi:10.1016/j.antiviral.2012.09.007
-
56. Kaufmann B, Vogt MR, Goudsmit J, et al. Neutralization of West Nile virus by cross-linking of its surface proteins with Fab fragments of the human monoclonal antibody CR4354. Proc Natl Acad Sci U S A 2010; 107: 18950-18955. Medline doi:10.1073/pnas.1011036107
-
57. Dong H, Liu L, Zou G, et al. Structural and functional analyses of a conserved hydrophobic pocket of flavivirus methyltransferase. J Biol Chem 2010; 285: 32586-32595. Medline doi:10.1074/jbc.M110.129197
-
58. Cherrier MV, Kaufmann B, Nybakken GE, et al. Structural basis for the preferential recognition of immature flaviviruses by a fusion-loop antibody. EMBO J 2009; 28: 3269-3276. Medline doi:10.1038/emboj.2009.245
-
59. Robin G, Chappell K, Stoermer MJ, et al. Structure of West Nile virus NS3 protease: ligand stabilization of the catalytic conformation. J Mol Biol 2009; 385: 1568-1577. Medline doi:10.1016/j.jmb.2008.11.026
-
60. Mastrangelo E, Milani M, Bollati M, et al. Crystal structure and activity of Kunjin virus NS3 helicase; protease and helicase domain assembly in the full length NS3 protein. J Mol Biol 2007; 372: 444-455. Medline doi:10.1016/j.jmb.2007.06.055
-
61. Zhang Y, Kaufmann B, Chipman PR, Kuhn RJ, Rossmann MG. Structure of immature West Nile virus. J Virol 2007; 81: 6141-6145. Medline doi:10.1128/JVI.00037-07
-
62. Zhou Y, Ray D, Zhao Y, et al. Structure and function of flavivirus NS5 methyltransferase. J Virol 2007; 81: 3891-3903. Medline doi:10.1128/JVI.02704-06
-
63. Malet H, Egloff MP, Selisko B, et al. Crystal structure of the RNA polymerase domain of the West Nile virus non-structural protein 5. J Biol Chem 2007; 282: 10678-10689. Medline doi:10.1074/jbc.M607273200
-
64. Nybakken GE, Oliphant T, Johnson S, Burke S, Diamond MS, Fremont DH. Structural basis of West Nile virus neutralization by a therapeutic antibody. Nature 2005; 437: 764-769. Medline doi:10.1038/nature03956
-
65. Dokland T, Walsh M, Mackenzie JM, Khromykh AA, Ee KH, Wang S. West Nile virus core protein; tetramer structure and ribbon formation. Structure 2004; 12: 1157-1163. Medline doi:10.1016/j.str.2004.04.024
-
66. Volk DE, Beasley DW, Kallick DA, Holbrook MR, Barrett AD, Gorenstein DG. Solution structure and antibody binding studies of the envelope protein domain III from the New York strain of West Nile virus. J Biol Chem 2004; 279: 38755-38761. Medline doi:10.1074/jbc.M402385200

Copyright © 2019 Nucleus Holdings Ltd. Part of Nucleus Global.
Design and Technology by Nucleus Global
Company registration No. 321 0712 (England & Wales). Registered Office address: Admiral House 76-78 Old Street, London EC1V 9AZ.