Discovery and development of NS5A inhibitors

Last updated
The HCV genome. NS5A in the bottom row, second from the right. HCV genome.png
The HCV genome. NS5A in the bottom row, second from the right.

Nonstructural protein 5A (NS5A) inhibitors are direct acting antiviral agents (DAAs) that target viral proteins, and their development was a culmination of increased understanding of the viral life cycle combined with advances in drug discovery technology. [1] [2] However, their mechanism of action is complex and not fully understood. [2] NS5A inhibitors were the focus of much attention when they emerged as a part of the first curative treatment for hepatitis C virus (HCV) infections in 2014. [3] Favorable characteristics have been introduced through varied structural changes, and structural similarities between NS5A inhibitors that are clinically approved are readily apparent. [4] [5] Despite the recent introduction of numerous new antiviral drugs, resistance is still a concern and these inhibitors are therefore always used in combination with other drugs. [6] [7]

Contents

Hepatitis C virus

HCV is a positive-sense single-stranded RNA virus that has been demonstrated to replicate in the hepatocytes of both humans and chimpanzees. A single HCV polyprotein is translated, and then cleaved by cellular and viral proteases into three structural proteins (core, E1, and E2) and seven nonstructural proteins (p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B). [8] [9]

HCV is among the leading causes of liver disease around the world. It is transmitted by blood and is most commonly contracted through the use of infected needles. [10] Patients with chronic HCV infection are at significant risk of cirrhosis and hepatocellular carcinoma, which are the leading causes of death for those infected. [11] [12]

The virus has been around for over a millennia and has been classified into six known genotypes, each of which contains numerous subtypes. The seventh remains uncharacterized. The genotype contracted dictates which specific treatments are viable. [13]

NS5A receptor

Basic structure and chemical properties

NS5A is a large hydrophilic phosphoprotein that is essential for the HCV life cycle and is found in association with virus-induced membrane vesicles, termed the membranous web. [14] [15] NS5A is a proline-rich protein composed of approximately 447 amino acids, which is divided into three domains. [16] [17] These domains are linked by two low-complexity sequences that are either serine- or proline-rich. [18] Domain I is a zinc binding domain and X-ray crystallography studies indicated alternative dimer conformations of domain I of NS5A. [19] [20] [21] Domain II and III are unstructured, shown by NMR studies. [16] [22] Domain I is preceded by an N-terminal amphipathic helix which allows the protein to associate with endoplasmic reticulum-derived membranes. [22] [23] [24] Although X-ray crystallographic studies revealed dimer conformations of NS5A domain1, recent in solution structural characterization studies showed that NS5A proteins form higher-order structures by dimeric subunits of NS5A domain 1. [25] Moreover, the overall structural model of NS5A highlights the variability of intrinsic conformations of the D2 and D3 domains between HCV genotypes. [26] Therefore, it is still under debate which conformation\s of NS5A is functional and also targeted by NS5A inhibitors.[ citation needed ]

NS5A mainly exists in two distinct phosphorylated forms, a hypophosphorylated and a hyperphosphorylated form, but the exact function of the phosphorylation has not been determined. [17] [18] [27]

Function

The NS5A protein plays an important role in viral RNA replication, viral assembly, and complex interactions with cellular functions. [2] [17] The protein has been implicated in the modulation of host defenses, apoptosis, the cell cycle, and stress-responsive pathways. [27] However, its function and complete structure have yet to be elucidated. [16]

NS5A seems to be key in triggering the formation of the membranous web in the absence of other similar nonstructural proteins. [15] Many proteins within the host cell can be affected by NS5A, e.g. phosphatidylinositol 4-kinase IIIα (PI4KIIIα), a kinase required for the replication of HCV. This kinase takes part in the biosynthesis of phosphatidylinositol 4-phosphate (PI4P) by interacting with NS5A, which stimulates its activity and appears to improve the integrity of the membranous web. [15] [28] [29]

Recently, the central role of NS5A in viral proliferation has made it the target for drug development. As a result, new antiviral agents have been introduced for the treatment of HCV. [2]

Mechanism of action

NS5A inhibitors have been developed to target the NS5A protein. These inhibitors have achieved a significant reduction in HCV RNA blood levels and can therefore be considered as potent antivirals. Their mechanism of action is thought to be diverse but the exact mechanism is not fully understood. [2] [30] Most studies assume that NS5A inhibitors act on two essential stages of the HCV life cycle; the replication of the genomic RNA, and virion assembly. Other studies propose an alteration of host cell factors as a possible third mechanism. [2] [15] [31]

NS5A inhibitor's supposed mechanism of action. The inhibitor binds to NS5A domain 1 and prevents RNA from binding, therefore disrupting RNA replication. Mechanism of action for NS5A inhibitors.png
NS5A inhibitor's supposed mechanism of action. The inhibitor binds to NS5A domain 1 and prevents RNA from binding, therefore disrupting RNA replication.

The structure of NS5A inhibitors is characterized by dimeric symmetry. This suggests that NS5A inhibitors act on dimers of NS5A. [32] A number of modeling studies have shown that daclatasvir, which is an NS5A inhibitor, only binds to the "back-to-back" NS5A dimer and that the binding has to be symmetrical. Other modeling studies have shown that binding to other conformations of NS5A might be possible, as well as asymmetrical binding. [30] Research has shown that daclatasvir's target is most likely domain I of NS5A. [31] Even though the mechanism is not completely understood, it has been demonstrated that the inhibitors downregulate NS5A hyperphosphorylation, leading to the suppression of HCV replication and its processing of polyproteins, as well as resulting in an unusual protein location. [31] [33] Hitherto, this inhibition was thought to require only NS5A domain I, but not domains II and III. [33] However, recent studies have shown that both domains I and II are relevant to this disruption of RNA replication. [34]

NS5A inhibitors appear to furthermore disrupt the formation of new replicase complexes resulting in a gradual slowing of viral RNA synthesis. Effect on previously formed complexes has yet to be demonstrated. [34] [35]

Available evidence suggests that NS5A inhibitors modify the location of NS5A inside the cell. This may cause abnormal assembly leading to malformed viruses. [2] Some studies have revealed that inhibition of the viral assembly has a more important role in RNA reduction than viral replication reduction. [35] [36]

Studies have shown that NS5A inhibitors block the formation of the membranous web, which protects the viral genome and features the main sites for viral replication and assembly. [15] [31] [37] This mechanism is thought to be independent of RNA replication, but seems to be affected by NS5A inhibitors blocking the formation of the PI4KIIIα-NS5A complex, essential to the synthesis of the PI4P, resulting in decreased integrity of the membranous web and therefore reduced HCV RNA replication. [15] [28] [38]

History

HCV research has taken great strides in recent years with the discovery and clinical development of multiple new HCV drugs. Among those drugs are the DAAs which include NS5A inhibitors. [39] NS5A inhibitors have been found particularly effective in the treatment of HCV where they have been used in combination with other protease inhibitors such as NS5B inhibitors (e.g. sofosbuvir), pegylated interferons (e.g. peginterferon alfa-2a), and ribonucleic analogs (e.g. ribavirin). [40] [41] [42] The ever present risk of viral strains developing resistance has been a main factor in why they are used in combination with one or more complementary drug. [43]

Adverse effects, and extensive and complicated drug regimens with accompanying low compliance rates, have been a hindrance in the development of antiviral treatments. The combination of NS5A and NS5B inhibitors has produced positive results in this regard. [44]

Drug discovery and development

Discovery

There are currently (January, 2024) six NS5A inhibitors clinically approved, while there are many more in development or undergoing clinical trials. Daclatasvir was the first clinically approved NS5A inhibitor. Structural similarities can be seen between daclatasvir and the more recent inhibitors as shown in black with differences in pink. Daclatasvir was developed by Bristol-Myers Squibb, ledipasvir and velpatasvir by Gilead Sciences, ombitasvir and pibrentasvir by AbbVie Inc. and elbasvir by Merck & Co. NS5A inhibitors.svg
There are currently (January, 2024) six NS5A inhibitors clinically approved, while there are many more in development or undergoing clinical trials. Daclatasvir was the first clinically approved NS5A inhibitor. Structural similarities can be seen between daclatasvir and the more recent inhibitors as shown in black with differences in pink. Daclatasvir was developed by Bristol-Myers Squibb, ledipasvir and velpatasvir by Gilead Sciences, ombitasvir and pibrentasvir by AbbVie Inc. and elbasvir by Merck & Co.

The discovery of NS5A inhibitors took place within the context of a pursuit for a treatment for HCV. NS5A is among the seven nonstructural proteins that form a complex with viral RNA within infected cells to initiate HCV replication. [45] HCV research has produced several DAAs including NS3A, NS4A and NS5B inhibitors, as well as NS5A inhibitors. [46]

Development

The development of antiviral drugs capable of interfering with the proteins responsible for viral replication has been intimately linked with advancements in techniques for establishing the efficient cell culture systems needed to screen for them. [46]

In 1999 a breakthrough came when a full-length consensus genome cloned from HCV RNA was found to replicate at high levels when transfected into a human hepatoma cell line. [47] This method has since been improved upon with the use of cell culture-adaptive mutations that enhance RNA replication. [48]

Screening has now produced a number of NS5A inhibitors, which have been incorporated into treatments for HCV. The first in this new class of drugs was daclatasvir (Daklinza), gaining first global approval from the Japanese Ministry of Health, Labour and Welfare (MHLW) in July 2014 in combination with asunaprevir. [49] Daclatasvir received FDA approval in July 2015. [50] Other drugs have since been approved, among them notably the first FDA-approved NS5A inhibitor ledipasvir, approved October 2014 in combination with sofosbuvir to comprise the HCV drug Harvoni. [51] [52]

Although NS5A inhibitors have proven effective antivirals, they must be used alongside complementary antiviral drugs due to how quickly they lead to the development of resistant mutations when given as a single agent. [53] This has shaped the focus of NS5A inhibitor development, from which asymmetrical variants that metabolize into analogues with complementary resistance profiles have emerged, amongst other discoveries. [54]

Structure-activity relationship

The structural similarities between the inhibitors are readily apparent. [4] The appendages of the central core are typically symmetrical and have an imidazole-proline structure. [5] The natural L-configuration of the proline derivatives was found to be critical for inhibition since the unnatural D-configuration had drastically weaker activity. The potency of the inhibitors was correspondingly sensitive to changes in the amine capping element. These observations suggest that the amine region of the molecules plays an important role in the inhibitory activity. [55]

Favorable characteristics in an NS5A inhibitor include high potency and long plasma half-life in order to achieve a once-daily-dosage. Slightly asymmetrical appendages, as seen in ledipasvir, were found to have distinctive benefits for the optimization of inhibitor potency and pharmacokinetics. [51] The structure of the central core changes the spacing and the projection of the appendages as well as the position of the lipophilicity in the central core, which affects inhibitory activity notably. Structures with fused central rings consistently show greater inhibitory activity, whereas less lipophilic central cores provide weaker activity. [4] Symmetrical bis-imidazol structures, such as daclatasvir, experience a loss in potency when fluorene is substituted for the biaryl group. This substitution also gives rise to some serious stability problems. [51] [56] However, a smaller lipophilic connector such as difluoromethylene generates the most potent inhibitor in an asymmetrical structure. Additionally, it provides improved bioavailability and more favorable plasma half-life. There is also a remarkable increase in potency when phenyl is replaced with naphthyl as a central core. This increase is significantly higher in an asymmetrical structure than it is in a symmetrical structure. [51] [55] In asymmetrical structures, a difference in potency between the phenyl-alkyne inhibitors demonstrates the importance of the position of the lipophilicity. A more centrally located alkyne, which is a less lipophilic connector than phenyl, improves potency. [4] [5] [51]

The effect of structural changes in the central core (represented as X) of a symmetrical benzimidazole-benzimidazole structure on inhibitory activity [4] [51]

Symmetrical structure .png

StructureActivity
XIC50 (nM)Inhibitory activity

Chemical structure one.png

>44None

Chemical structure two.png

>44None

Chemical structure three.png

11Very weak

Chemical structure four.png

1.7Weak

Chemical structure five.png

0.50Moderate

Chemical structure six.png

3.7Weak

Chemical structure seven.png

0.11Moderate

Chemical structure eight.png

0.20Moderate
The effect of structural changes in the central core (represented as X) of an asymmetrical imidazole-benzimidazole structure on inhibitory activity [4] [51]

Symmetrical structure two.png

StructureActivity
XIC50 (nM)Inhibitory activity

Chemical structure nine.png

>44None

Chemical structure ten.png

0.071Moderate

Chemical structure elleven.png

2.5Weak

Chemical structure twelve.png

0.38Moderate

Chemical structure thirteen.png

0.20Moderate

Chemical structure fourteen.png

0.17Moderate

Chemical structure fifteen.png

0.040Strong
The effect of structural changes in the central core (represented as X) of a symmetrical imidazole-biaryl-imidazole structure on inhibitory activity [4] [51]

Unsymmetrical structure.png

StructureActivity
XIC50 (nM)Inhibitory activity
CH20.094Strong
CO0.30Moderate
C(CH3)21.2Weak

Resistance

The potential HCV resistance against DAA drugs is a concern. [6] Among the HCV quasispecies there are pre-existing variants with the potential to confer resistance to NS5A inhibitors without having any previous exposure to those drugs. Generally, the replication of these variants happens only in minute quantities, making them undetectable by current techniques. On the other hand, it is possible to selectively grow immune variants in the presence of NS5A inhibitors. [2] HCV resistance is characterized by a certain escape pattern. This pattern is often associated with amino acid substitutions that confer upon the virus a robust drug resistance without impairing the viral fitness. [2] [57] It has been established that NS5A inhibitors possess a relatively low threshold for resistance, and variants that are associated with NS5A resistance have been shown to endure for up to six months in patients following treatment cessation. [58] Therefore, combination therapies produce higher efficacy and shorter treatment periods. [7]

Future research and new generations of NS5A inhibitors

DAA developers face foreseeable challenges in the years to come. Therapeutic gaps for individuals with complicating conditioned such as chronic kidney disease and cirrhosis will need to be bridged. Shorter therapies with milder side effects would yield greater adherence, and the ever present spectre of drug resistance is looming. The highly adaptive HCV has evolved into a number of different genomes that all need to be adequately treated, preferably with pan-genotypic regimens. [59]

Some of these challenges already have possible solutions in sight. The protease inhibitor ABT-493 and the next-generation NS5A inhibitor ABT-530 are considered active against all HCV genotypes, including the hard to treat genotype 3. [42] [59] In vitro, ABT-530 showed potency against the resistance associated variants which are immune to the first generations of NS5A inhibitors, including ledipasvir, daclatasvir and ombitasvir. [42] Because this drug combination has the additional quality of being hepatically cleared, it holds the promise that patients with chronic kidney disease and HCV could receive a safe, non-sofosbuvir-based treatment in the near future. [59]

At least three drug combinations for the treatment of HCV are in the pipeline to be approved in 2016-2017: Sofosbuvir in combination with velpatasvir, ABT-493 in combination with ABT-530, and grazoprevir in combination with elbasvir, of which velpatasvir, ABT-530 and elbasvir are NS5A inhibitors. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Antiviral drug</span> Medication used to treat a viral infection

Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Antiviral drugs are a class of antimicrobials, a larger group which also includes antibiotic, antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies. Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections. They should be distinguished from virucides, which are not medication but deactivate or destroy virus particles, either inside or outside the body. Natural virucides are produced by some plants such as eucalyptus and Australian tea trees.

Hepatitis D is a type of viral hepatitis caused by the hepatitis delta virus (HDV). HDV is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a satellite because it can propagate only in the presence of the hepatitis B virus (HBV). Transmission of HDV can occur either via simultaneous infection with HBV (coinfection) or superimposed on chronic hepatitis B or hepatitis B carrier state (superinfection).

<span class="mw-page-title-main">Hepatitis C virus</span> Species of virus

The hepatitis C virus (HCV) is a small, enveloped, positive-sense single-stranded RNA virus of the family Flaviviridae. The hepatitis C virus is the cause of hepatitis C and some cancers such as liver cancer and lymphomas in humans.

<span class="mw-page-title-main">Hepatitis A virus internal ribosome entry site (IRES)</span>

This family represents the internal ribosome entry site (IRES) of the hepatitis A virus. HAV IRES is a 450 nucleotide long sequence located in the 735 nt long 5’ UTR of Hepatitis A viral RNA genome. IRES elements allow cap and end-independent translation of mRNA in the host cell. The IRES achieves this by mediating the internal initiation of translation by recruiting a ribosomal 40S pre-initiation complex directly to the initiation codon and eliminates the requirement for eukaryotic initiation factor, eIF4F.

<span class="mw-page-title-main">Mitochondrial antiviral-signaling protein</span> Protein-coding gene in the species Homo sapiens

Mitochondrial antiviral-signaling protein (MAVS) is a protein that is essential for antiviral innate immunity. MAVS is located in the outer membrane of the mitochondria, peroxisomes, and mitochondrial-associated endoplasmic reticulum membrane (MAM). Upon viral infection, a group of cytosolic proteins will detect the presence of the virus and bind to MAVS, thereby activating MAVS. The activation of MAVS leads the virally infected cell to secrete cytokines. This induces an immune response which kills the host's virally infected cells, resulting in clearance of the virus.

<span class="mw-page-title-main">Hepatitis C virus nonstructural protein 5A</span>

Nonstructural protein 5A (NS5A) is a zinc-binding and proline-rich hydrophilic phosphoprotein that plays a key role in Hepatitis C virus RNA replication. It appears to be a dimeric form without trans-membrane helices.

<span class="mw-page-title-main">Hepatitis C virus nonstructural protein 2</span>

Nonstructural protein 2 (NS2) is a viral protein found in the hepatitis C virus. It is also produced by influenza viruses, and is alternatively known as the nuclear export protein (NEP).

miR-122

miR-122 is a miRNA that is conserved among vertebrate species. miR-122 is not present in invertebrates, and no close paralogs of miR-122 have been detected. miR-122 is highly expressed in the liver, where it has been implicated as a regulator of fatty-acid metabolism in mouse studies. Reduced miR-122 levels are associated with hepatocellular carcinoma. miR-122 also plays an important positive role in the regulation of hepatitis C virus replication.

RIG-I-like receptors are a type of intracellular pattern recognition receptor involved in the recognition of viruses by the innate immune system. RIG-I is the best characterized receptor within the RIG-I like receptor (RLR) family. Together with MDA5 and LGP2, this family of cytoplasmic pattern recognition receptors (PRRs) are sentinels for intracellular viral RNA that is a product of viral infection. The RLR receptors provide frontline defence against viral infections in most tissues.

<span class="mw-page-title-main">Sofosbuvir</span> Chemical compound

Sofosbuvir, sold under the brand name Sovaldi among others, is a medication used to treat hepatitis C. It is taken by mouth.

<span class="mw-page-title-main">Viperin</span>

Radical S-adenosyl methionine domain-containing protein 2 is a protein that in humans is encoded by the RSAD2 gene. RSAD2 is a multifunctional protein in viral processes that is an interferon stimulated gene. It has been reported that viperin could be induced by either IFN-dependent or IFN-independent pathways and certain viruses may use viperin to increase their infectivity.

<span class="mw-page-title-main">Daclatasvir</span> Chemical compound

Daclatasvir, sold under the brand name Daklinza, is an antiviral medication used in combination with other medications to treat hepatitis C (HCV). The other medications used in combination include sofosbuvir, ribavirin, and interferon, vary depending on the virus type and whether the person has cirrhosis. It is taken by mouth.

<span class="mw-page-title-main">Simeprevir</span> Chemical compound

Simeprevir, sold under the brand name Olysio among others, is a medication used in combination with other medications for the treatment of hepatitis C. It is specifically used for hepatitis C genotype 1 and 4. Medications it is used with include sofosbuvir or ribavirin and peginterferon-alfa. Cure rates are in 80s to 90s percent. It may be used in those who also have HIV/AIDS. It is taken by mouth once daily for typically 12 weeks.

<span class="mw-page-title-main">Ledipasvir</span> Hepatitis C drug

Ledipasvir is a drug for the treatment of hepatitis C that was developed by Gilead Sciences. After completing Phase III clinical trials, on February 10, 2014, Gilead filed for U.S. approval of a ledipasvir/sofosbuvir fixed-dose combination tablet for genotype 1 hepatitis C. The ledipasvir/sofosbuvir combination is a direct-acting antiviral agent that interferes with HCV replication and can be used to treat patients with genotypes 1a or 1b without PEG-interferon or ribavirin.

<span class="mw-page-title-main">Hepatitis C virus nonstructural protein 5B</span>

Nonstructural protein 5B (NS5B) is a viral protein found in the hepatitis C virus (HCV). It is an RNA-dependent RNA polymerase, having the key function of replicating HCV's viral RNA by using the viral positive RNA strand as a template to catalyze the polymerization of ribonucleoside triphosphates (rNTP) during RNA replication. Several crystal structures of NS5B polymerase in several crystalline forms have been determined based on the same consensus sequence BK. The structure can be represented by a right hand shape with fingers, palm, and thumb. The encircled active site, unique to NS5B, is contained within the palm structure of the protein. Recent studies on NS5B protein genotype 1b strain J4's (HC-J4) structure indicate a presence of an active site where possible control of nucleotide binding occurs and initiation of de-novo RNA synthesis. De-novo adds necessary primers for initiation of RNA replication.

<span class="mw-page-title-main">Ledipasvir/sofosbuvir</span> Medication used to treat hepatitis C

Ledipasvir/sofosbuvir, sold under the trade name Harvoni among others, is a medication used to treat hepatitis C. It is a fixed-dose combination of ledipasvir and sofosbuvir. Cure rates are 94% to 99% in people infected with hepatitis C virus (HCV) genotype 1. Some evidence also supports use in HCV genotype 3 and 4. It is taken daily by mouth for 8–24 weeks.

Glecaprevir/pibrentasvir (G/P), sold under the brand names Mavyret and Maviret, is a fixed-dose combination medication used to treat hepatitis C. It contains glecaprevir and pibrentasvir. It works against all six types of hepatitis C. At twelve weeks following treatment between 81% and 100% of people have no evidence of hepatitis C. It is taken once a day by mouth with food.

<span class="mw-page-title-main">NS5B inhibitor</span> Class of pharmaceutical drugs

Non-structural protein 5B (NS5B) inhibitors are a class of direct-acting antivirals widely used in the treatment of chronic hepatitis C. Depending on site of action and chemical composition, NS5B inhibitors may be categorized into three classes—nucleoside active site inhibitors (NIs), non-nucleoside allosteric inhibitors, and pyrophosphate analogues. Subsequently, all three classes are then subclassified. All inhibit RNA synthesis by NS5B but at different stages/sites resulting in inability of viral RNA replication. Expression of direct-acting NS5B inhibitors does not take place in cells that are not infected by hepatitis C virus, which seems to be beneficial for this class of drugs.

Francis "Frank" Vincent Chisari is a physician, experimental pathologist, virologist, and immunologist, known for his research on virus-host interactions of hepatitis B and hepatitis C.

<span class="mw-page-title-main">Bemnifosbuvir</span> Chemical compound

Bemnifosbuvir is an antiviral drug invented by Atea Pharmaceuticals and licensed to Roche for clinical development, a novel nucleotide analog prodrug originally developed for the treatment of hepatitis C. Bemnifosbuvir is the orally bioavailable hemisulfate salt of AT-511, which is metabolized in several steps to the active nucleotide triphosphate AT-9010, acting as an RNA polymerase inhibitor and thereby interfering with viral replication. Bemnifosbuvir has been researched for the treatment of coronavirus diseases such as that produced by SARS-CoV-2. It showed good results in early clinical trials but had inconsistent results at later stages, so the planned Phase 3 trials are being redesigned and results are not expected until late 2022.

References

  1. Gogela, Neliswa A.; Lin, Ming V.; Wisocky, Jessica L.; Chung, Raymond T. (12 March 2015). "Enhancing Our Understanding of Current Therapies for Hepatitis C Virus (HCV)". Current HIV/AIDS Reports. 12 (1): 68–78. doi:10.1007/s11904-014-0243-7. PMC   4373591 . PMID   25761432.
  2. 1 2 3 4 5 6 7 8 9 Pawlotsky, Jean-Michel (August 2013). "NS5A inhibitors in the treatment of hepatitis C". Journal of Hepatology. 59 (2): 375–382. doi: 10.1016/j.jhep.2013.03.030 . PMID   23567084.
  3. Do, Albert; Mittal, Yash; Liapakis, AnnMarie; Cohen, Elizabeth; Chau, Hong; Bertuccio, Claudia; Sapir, Dana; Wright, Jessica; Eggers, Carol; Drozd, Kristine; Ciarleglio, Maria; Deng, Yanhong; Lim, Joseph K.; Jhaveri, Ravi (27 August 2015). "Drug Authorization for Sofosbuvir/Ledipasvir (Harvoni) for Chronic HCV Infection in a Real-World Cohort: A New Barrier in the HCV Care Cascade". PLOS ONE. 10 (8): e0135645. Bibcode:2015PLoSO..1035645D. doi: 10.1371/journal.pone.0135645 . PMC   4552165 . PMID   26312999.
  4. 1 2 3 4 5 6 7 8 Tong, Ling; Yu, Wensheng; Coburn, Craig A.; Meinke, Peter T.; Nair, Anilkumar G.; Dwyer, Michael P.; Chen, Lei; Selyutin, Oleg; Rosenblum, Stuart B.; Jiang, Yueheng; Fells, James; Hu, Bin; Zhong, Bin; Soll, Richard M.; Liu, Rong; Agrawal, Sony; Xia, Ellen; Zhai, Ying; Kong, Rong; Ingravallo, Paul; Nomeir, Amin; Asante-Appiah, Ernest; Kozlowski, Joseph A. (July 2016). "Alternative core development around the tetracyclic indole class of HCV NS5A inhibitors". Bioorganic & Medicinal Chemistry Letters. 26 (20): 5132–5137. doi: 10.1016/j.bmcl.2016.07.057 . PMID   27634194.
  5. 1 2 3 Lemm, J. A.; Leet, J. E.; O'Boyle, D. R.; Romine, J. L.; Huang, X. S.; Schroeder, D. R.; Alberts, J.; Cantone, J. L.; Sun, J.-H.; Nower, P. T.; Martin, S. W.; Serrano-Wu, M. H.; Meanwell, N. A.; Snyder, L. B.; Gao, M. (16 May 2011). "Discovery of Potent Hepatitis C Virus NS5A Inhibitors with Dimeric Structures". Antimicrobial Agents and Chemotherapy. 55 (8): 3795–3802. doi:10.1128/AAC.00146-11. PMC   3147613 . PMID   21576451.
  6. 1 2 Fridell, R. A.; Qiu, D.; Wang, C.; Valera, L.; Gao, M. (28 June 2010). "Resistance Analysis of the Hepatitis C Virus NS5A Inhibitor BMS-790052 in an In Vitro Replicon System". Antimicrobial Agents and Chemotherapy. 54 (9): 3641–3650. doi:10.1128/AAC.00556-10. PMC   2935007 . PMID   20585111.
  7. 1 2 3 Asselah, Tarik; Boyer, Nathalie; Saadoun, David; Martinot-Peignoux, Michele; Marcellin, Patrick (January 2016). "Direct-acting antivirals for the treatment of hepatitis C virus infection: optimizing current IFN-free treatment and future perspectives". Liver International. 36: 47–57. doi: 10.1111/liv.13027 . PMID   26725897.
  8. Halliday, John; Klenerman, Paul; Barnes, Eleanor (9 January 2014). "Vaccination for hepatitis C virus: closing in on an evasive target". Expert Review of Vaccines. 10 (5): 659–672. doi:10.1586/erv.11.55. PMC   3112461 . PMID   21604986.
  9. Grakoui, A; Wychowski, C; Lin, C; Feinstone, S M; Rice, C M (1 March 1993). "Expression and identification of hepatitis C virus polyprotein cleavage products". Journal of Virology. 67 (3): 1385–1395. doi:10.1128/JVI.67.3.1385-1395.1993. ISSN   0022-538X. PMC   237508 . PMID   7679746.
  10. Chan, Juliana (May 2014). "Hepatitis C". Disease-a-Month. 60 (5): 201–212. doi:10.1016/j.disamonth.2014.04.002. PMID   24863270.
  11. Seeff, Leonard B. (November 2002). "Natural history of chronic hepatitis C". Hepatology. 36 (5): s35–s46. doi: 10.1053/jhep.2002.36806 . PMID   12407575.
  12. Liang, T. Jake; Rehermann, Barbara; Seeff, Leonard B.; Hoofnagle, Jay H. (15 February 2000). "Pathogenesis, Natural History, Treatment, and Prevention of Hepatitis C". Annals of Internal Medicine. 132 (4): 296–305. doi:10.7326/0003-4819-132-4-200002150-00008. PMID   10681285. S2CID   23226526.
  13. Pybus, O. G.; Barnes, E.; Taggart, R.; Lemey, P.; Markov, P. V.; Rasachak, B.; Syhavong, B.; Phetsouvanah, R.; Sheridan, I.; Humphreys, I. S.; Lu, L.; Newton, P. N.; Klenerman, P. (29 October 2008). "Genetic History of Hepatitis C Virus in East Asia". Journal of Virology. 83 (2): 1071–1082. doi:10.1128/JVI.01501-08. PMC   2612398 . PMID   18971279.
  14. Tellinghuisen, T. L.; Foss, K. L.; Treadaway, J. C.; Rice, C. M. (21 November 2007). "Identification of Residues Required for RNA Replication in Domains II and III of the Hepatitis C Virus NS5A Protein". Journal of Virology. 82 (3): 1073–1083. doi:10.1128/JVI.00328-07. PMC   2224455 . PMID   18032500.
  15. 1 2 3 4 5 6 Reghellin, V.; Donnici, L.; Fenu, S.; Berno, V.; Calabrese, V.; Pagani, M.; Abrignani, S.; Peri, F.; De Francesco, R.; Neddermann, P. (15 September 2014). "NS5A Inhibitors Impair NS5A-Phosphatidylinositol 4-Kinase III Complex Formation and Cause a Decrease of Phosphatidylinositol 4-Phosphate and Cholesterol Levels in Hepatitis C Virus-Associated Membranes". Antimicrobial Agents and Chemotherapy. 58 (12): 7128–7140. doi:10.1128/AAC.03293-14. PMC   4249536 . PMID   25224012.
  16. 1 2 3 Yamasaki, Lilian HT; Arcuri, Helen A; Jardim, Ana Carolina G; Bittar, Cintia; de Carvalho-Mello, Isabel Maria VG; Rahal, Paula (2012). "New insights regarding HCV-NS5A structure/function and indication of genotypic differences". Virology Journal. 9 (1): 14. doi: 10.1186/1743-422X-9-14 . PMC   3271958 . PMID   22239820.
  17. 1 2 3 Masaki, T.; Matsunaga, S.; Takahashi, H.; Nakashima, K.; Kimura, Y.; Ito, M.; Matsuda, M.; Murayama, A.; Kato, T.; Hirano, H.; Endo, Y.; Lemon, S. M.; Wakita, T.; Sawasaki, T.; Suzuki, T. (23 April 2014). "Involvement of Hepatitis C Virus NS5A Hyperphosphorylation Mediated by Casein Kinase I- in Infectious Virus Production". Journal of Virology. 88 (13): 7541–7555. doi:10.1128/JVI.03170-13. PMC   4054430 . PMID   24760886.
  18. 1 2 Ross-Thriepland, D.; Harris, M. (20 November 2013). "Insights into the Complexity and Functionality of Hepatitis C Virus NS5A Phosphorylation". Journal of Virology. 88 (3): 1421–1432. doi:10.1128/JVI.03017-13. PMC   3911623 . PMID   24257600.
  19. Rice, Charles M.; Marcotrigiano, Joseph; Tellinghuisen, Timothy L. (May 2005). "Structure of the zinc-binding domain of an essential component of the hepatitis C virus replicase". Nature. 435 (7040): 374–379. Bibcode:2005Natur.435..374T. doi:10.1038/nature03580. ISSN   1476-4687. PMC   1440517 . PMID   15902263.
  20. Cronin, Ciarán N.; Wells, Peter A.; Hickey, Michael J.; Brodsky, Oleg; Love, Robert A. (2009-05-01). "Crystal Structure of a Novel Dimeric Form of NS5A Domain I Protein from Hepatitis C Virus". Journal of Virology. 83 (9): 4395–4403. doi:10.1128/JVI.02352-08. ISSN   1098-5514. PMC   2668466 . PMID   19244328.
  21. Lambert, Sebastian M.; Langley, David R.; Garnett, James A.; Angell, Richard; Hedgethorne, Katy; Meanwell, Nicholas A.; Matthews, Steve J. (2014-06-01). "The crystal structure of NS5A domain 1 from genotype 1a reveals new clues to the mechanism of action for dimeric HCV inhibitors". Protein Science. 23 (6): 723–734. doi:10.1002/pro.2456. ISSN   1469-896X. PMC   4093949 . PMID   24639329.
  22. 1 2 Foster, T. L.; Belyaeva, T.; Stonehouse, N. J.; Pearson, A. R.; Harris, M. (30 June 2010). "All Three Domains of the Hepatitis C Virus Nonstructural NS5A Protein Contribute to RNA Binding". Journal of Virology. 84 (18): 9267–9277. doi:10.1128/JVI.00616-10. PMC   2937630 . PMID   20592076.
  23. Fridell, R. A.; Qiu, D.; Valera, L.; Wang, C.; Rose, R. E.; Gao, M. (18 May 2011). "Distinct Functions of NS5A in Hepatitis C Virus RNA Replication Uncovered by Studies with the NS5A Inhibitor BMS-790052". Journal of Virology. 85 (14): 7312–7320. doi:10.1128/JVI.00253-11. PMC   3126594 . PMID   21593143.
  24. 1 2 Ascher, David B.; Wielens, Jerome; Nero, Tracy L.; Doughty, Larissa; Morton, Craig J.; Parker, Michael W. (23 April 2014). "Potent hepatitis C inhibitors bind directly to NS5A and reduce its affinity for RNA". Scientific Reports. 4: 4765. Bibcode:2014NatSR...4E4765A. doi:10.1038/srep04765. PMC   3996483 . PMID   24755925.
  25. Beldar, Serap; Manimekalai, Malathy Sony Subramanian; Cho, Nam-Joon; Baek, Kwanghee; Grüber, Gerhard; Yoon, Ho Sup (2018). "Self-association and conformational variation of NS5A domain 1 of hepatitis C virus". Journal of General Virology. 99 (2): 194–208. doi: 10.1099/jgv.0.001000 . PMID   29300159.
  26. Badillo, Aurelie; Receveur-Brechot, Véronique; Sarrazin, Stéphane; Cantrelle, François-Xavier; Delolme, Frédéric; Fogeron, Marie-Laure; Molle, Jennifer; Montserret, Roland; Bockmann, Anja (2017-06-07). "Overall Structural Model of NS5A Protein from Hepatitis C Virus and Modulation by Mutations Confering [sic] Resistance of Virus Replication to Cyclosporin A". Biochemistry. 56 (24): 3029–3048. doi:10.1021/acs.biochem.7b00212. PMID   28535337.
  27. 1 2 Xiong, Wei; Yang, Jie; Wang, Mingzhen; Wang, Hailong; Rao, Zhipeng; Zhong, Cheng; Xin, Xiu; Mo, Lin; Yu, Shujuan; Shen, Chao; Zheng, Congyi; Diamond, M. S. (15 July 2015). "Vinexin β Interacts with Hepatitis C Virus NS5A, Modulating Its Hyperphosphorylation To Regulate Viral Propagation". Journal of Virology. 89 (14): 7385–7400. doi:10.1128/JVI.00567-15. PMC   4473562 . PMID   25972535.
  28. 1 2 Reiss, Simon; Rebhan, Ilka; Backes, Perdita; Romero-Brey, Ines; Erfle, Holger; Matula, Petr; Kaderali, Lars; Poenisch, Marion; Blankenburg, Hagen; Hiet, Marie-Sophie; Longerich, Thomas; Diehl, Sarah; Ramirez, Fidel; Balla, Tamas; Rohr, Karl; Kaul, Artur; Bühler, Sandra; Pepperkok, Rainer; Lengauer, Thomas; Albrecht, Mario; Eils, Roland; Schirmacher, Peter; Lohmann, Volker; Bartenschlager, Ralf (January 2011). "Recruitment and Activation of a Lipid Kinase by Hepatitis C Virus NS5A Is Essential for Integrity of the Membranous Replication Compartment". Cell Host & Microbe. 9 (1): 32–45. doi:10.1016/j.chom.2010.12.002. PMC   3433060 . PMID   21238945.
  29. Lim, Y.-S.; Hwang, S. B. (5 February 2011). "Hepatitis C Virus NS5A Protein Interacts with Phosphatidylinositol 4-Kinase Type III and Regulates Viral Propagation". Journal of Biological Chemistry. 286 (13): 11290–11298. doi: 10.1074/jbc.M110.194472 . PMC   3064185 . PMID   21297162.
  30. 1 2 Ahmed, Marawan; Pal, Abhishek; Houghton, Michael; Barakat, Khaled (3 August 2016). "A Comprehensive Computational Analysis for the Binding Modes of Hepatitis C Virus NS5A Inhibitors: The Question of Symmetry". ACS Infectious Diseases. 2 (11): 872–881. doi:10.1021/acsinfecdis.6b00113. PMID   27933783.
  31. 1 2 3 4 Issur, Moheshwarnath; Götte, Matthias (6 November 2014). "Resistance Patterns Associated with HCV NS5A Inhibitors Provide Limited Insight into Drug Binding". Viruses. 6 (11): 4227–4241. doi: 10.3390/v6114227 . PMC   4246218 . PMID   25384189.
  32. Lambert, Sebastian M.; Langley, David R.; Garnett, James A.; Angell, Richard; Hedgethorne, Katy; Meanwell, Nicholas A.; Matthews, Steve J. (June 2014). "The crystal structure of NS5A domain 1 from genotype 1a reveals new clues to the mechanism of action for dimeric HCV inhibitors". Protein Science. 23 (6): 723–734. doi:10.1002/pro.2456. PMC   4093949 . PMID   24639329.
  33. 1 2 Qiu, D.; Lemm, J. A.; O'Boyle, D. R.; Sun, J.-H.; Nower, P. T.; Nguyen, V.; Hamann, L. G.; Snyder, L. B.; Deon, D. H.; Ruediger, E.; Meanwell, N. A.; Belema, M.; Gao, M.; Fridell, R. A. (27 July 2011). "The effects of NS5A inhibitors on NS5A phosphorylation, polyprotein processing and localization". Journal of General Virology. 92 (11): 2502–2511. doi: 10.1099/vir.0.034801-0 . PMID   21795470.
  34. 1 2 Belema, Makonen; Lopez, Omar D.; Bender, John A.; Romine, Jeffrey L.; St. Laurent, Denis R.; Langley, David R.; Lemm, Julie A.; O’Boyle, Donald R.; Sun, Jin-Hua; Wang, Chunfu; Fridell, Robert A.; Meanwell, Nicholas A. (13 March 2014). "Discovery and Development of Hepatitis C Virus NS5A Replication Complex Inhibitors". Journal of Medicinal Chemistry. 57 (5): 1643–1672. doi:10.1021/jm401793m. PMID   24621191.
  35. 1 2 Guedj, J.; Dahari, H.; Rong, L.; Sansone, N. D.; Nettles, R. E.; Cotler, S. J.; Layden, T. J.; Uprichard, S. L.; Perelson, A. S. (19 February 2013). "Modeling shows that the NS5A inhibitor daclatasvir has two modes of action and yields a shorter estimate of the hepatitis C virus half-life". Proceedings of the National Academy of Sciences. 110 (10): 3991–3996. Bibcode:2013PNAS..110.3991G. doi: 10.1073/pnas.1203110110 . PMC   3593898 . PMID   23431163.
  36. McGivern, David R.; Masaki, Takahiro; Williford, Sara; Ingravallo, Paul; Feng, Zongdi; Lahser, Frederick; Asante-Appiah, Ernest; Neddermann, Petra; De Francesco, Raffaele; Howe, Anita Y.; Lemon, Stanley M. (August 2014). "Kinetic Analyses Reveal Potent and Early Blockade of Hepatitis C Virus Assembly by NS5A Inhibitors". Gastroenterology. 147 (2): 453–462.e7. doi:10.1053/j.gastro.2014.04.021. PMC   4107048 . PMID   24768676.
  37. Neufeldt, Christopher J.; Joyce, Michael A.; Van Buuren, Nicholas; Levin, Aviad; Kirkegaard, Karla; Gale Jr., Michael; Tyrrell, D. Lorne J.; Wozniak, Richard W.; Kuhn, Richard J. (10 February 2016). "The Hepatitis C Virus-Induced Membranous Web and Associated Nuclear Transport Machinery Limit Access of Pattern Recognition Receptors to Viral Replication Sites". PLOS Pathogens. 12 (2): e1005428. doi: 10.1371/journal.ppat.1005428 . PMC   4749181 . PMID   26863439.
  38. Berger, Carola; Romero-Brey, Inés; Radujkovic, Danijela; Terreux, Raphael; Zayas, Margarita; Paul, David; Harak, Christian; Hoppe, Simone; Gao, Min; Penin, Francois; Lohmann, Volker; Bartenschlager, Ralf (November 2014). "Daclatasvir-Like Inhibitors of NS5A Block Early Biogenesis of Hepatitis C Virus–Induced Membranous Replication Factories, Independent of RNA Replication". Gastroenterology. 147 (5): 1094–1105.e25. doi: 10.1053/j.gastro.2014.07.019 . PMID   25046163.
  39. 1 2 Zhang, Xingquan (January 2016). "Direct anti-HCV agents". Acta Pharmaceutica Sinica B. 6 (1): 26–31. doi:10.1016/j.apsb.2015.09.008. PMC   4724659 . PMID   26904396.
  40. Fung, A.; Jin, Z.; Dyatkina, N.; Wang, G.; Beigelman, L.; Deval, J. (14 April 2014). "Efficiency of Incorporation and Chain Termination Determines the Inhibition Potency of 2'-Modified Nucleotide Analogs against Hepatitis C Virus Polymerase". Antimicrobial Agents and Chemotherapy. 58 (7): 3636–3645. doi:10.1128/AAC.02666-14. PMC   4068585 . PMID   24733478.
  41. Bruder Costa, Juliana; Dufeu-Duchesne, Tania; Leroy, Vincent; Bertucci, Inga; Bouvier-Alias, Magali; Pouget, Noelle; Brevot-Lutton, Ophelie; Bourliere, Marc; Zoulim, Fabien; Plumas, Joel; Aspord, Caroline; Chemin, Isabelle A (27 June 2016). "Pegylated Interferon α-2a Triggers NK-Cell Functionality and Specific T-Cell Responses in Patients with Chronic HBV Infection without HBsAg Seroconversion". PLOS ONE. 11 (6): e0158297. Bibcode:2016PLoSO..1158297B. doi: 10.1371/journal.pone.0158297 . PMC   4922676 . PMID   27348813.
  42. 1 2 3 Poordad, Fred; Landis, Charles S.; Asatryan, Armen; Jackson, Daniel F.; Ng, Teresa I.; Fu, Bo; Lin, Chih-Wei; Yao, Betty; Kort, Jens (August 2016). "High antiviral activity of NS5A inhibitor ABT-530 with paritaprevir/ritonavir and ribavirin against hepatitis C virus genotype 3 infection". Liver International. 36 (8): 1125–1132. doi:10.1111/liv.13067. PMC   5067610 . PMID   26778412.
  43. Gaudieri, Silvana; Rauch, Andri; Pfafferott, Katja; Barnes, Eleanor; Cheng, Wendy; McCaughan, Geoff; Shackel, Nick; Jeffrey, Gary P.; Mollison, Lindsay; Baker, Ross; Furrer, Hansjakob; Günthard, Huldrych F.; Freitas, Elizabeth; Humphreys, Isla; Klenerman, Paul; Mallal, Simon; James, Ian; Roberts, Stuart; Nolan, David; Lucas, Michaela (April 2009). "Hepatitis C virus drug resistance and immune-driven adaptations: Relevance to new antiviral therapy". Hepatology. 49 (4): 1069–1082. doi: 10.1002/hep.22773 . PMID   19263475.
  44. Archer, Melissa; Steinvoort, Carin; Oderda, Gary. "UPDATE: New Hepatitis C Combination Agents" (PDF). Utah Department of Health. Archived from the original (PDF) on 27 December 2016. Retrieved 8 September 2016.
  45. Blight, K. J. (8 December 2000). "Efficient Initiation of HCV RNA Replication in Cell Culture". Science. 290 (5498): 1972–1974. Bibcode:2000Sci...290.1972B. doi:10.1126/science.290.5498.1972. PMID   11110665.
  46. 1 2 Conte, Immacolata; Giuliano, Claudio; Ercolani, Caterina; Narjes, Frank; Koch, Uwe; Rowley, Michael; Altamura, Sergio; Francesco, Raffaele De; Neddermann, Petra; Migliaccio, Giovanni; Stansfield, Ian (March 2009). "Synthesis and SAR of piperazinyl-N-phenylbenzamides as inhibitors of hepatitis C virus RNA replication in cell culture". Bioorganic & Medicinal Chemistry Letters. 19 (6): 1779–1783. doi:10.1016/j.bmcl.2009.01.066. PMID   19216075.
  47. Lohmann, V. (2 July 1999). "Replication of Subgenomic Hepatitis C Virus RNAs in a Hepatoma Cell Line". Science. 285 (5424): 110–113. doi:10.1126/science.285.5424.110. PMID   10390360.
  48. Lohmann, V.; Hoffmann, S.; Herian, U.; Penin, F.; Bartenschlager, R. (1 March 2003). "Viral and Cellular Determinants of Hepatitis C Virus RNA Replication in Cell Culture". Journal of Virology. 77 (5): 3007–3019. doi: 10.1128/JVI.77.5.3007-3019.2003 . PMC   149776 . PMID   12584326.
  49. Poole, Raewyn M. (13 August 2014). "Daclatasvir + Asunaprevir: First Global Approval". Drugs. 74 (13): 1559–1571. doi:10.1007/s40265-014-0279-4. PMID   25117197. S2CID   207488399.
  50. "FDA approves new treatment for chronic hepatitis C genotype 3 infections". FDA. 27 July 2015. Retrieved 29 September 2016.
  51. 1 2 3 4 5 6 7 8 Link, John O.; Taylor, James G.; Xu, Lianhong; Mitchell, Michael; Guo, Hongyan; Liu, Hongtao; Kato, Darryl; Kirschberg, Thorsten; Sun, Jianyu; Squires, Neil; Parrish, Jay; Keller, Terry; Yang, Zheng-Yu; Yang, Chris; Matles, Mike; Wang, Yujin; Wang, Kelly; Cheng, Guofeng; Tian, Yang; Mogalian, Erik; Mondou, Elsa; Cornpropst, Melanie; Perry, Jason; Desai, Manoj C. (13 March 2014). "Discovery of Ledipasvir (GS-5885): A Potent, Once-Daily Oral NS5A Inhibitor for the Treatment of Hepatitis C Virus Infection". Journal of Medicinal Chemistry. 57 (5): 2033–2046. doi:10.1021/jm401499g. PMID   24320933.
  52. Keating, Gillian M. (3 April 2015). "Ledipasvir/Sofosbuvir: A Review of Its Use in Chronic Hepatitis C". Drugs. 75 (6): 675–685. doi:10.1007/s40265-015-0381-2. PMID   25837989. S2CID   31943736.
  53. Nakamoto, Shingo (2014). "Hepatitis C virus NS5A inhibitors and drug resistance mutations". World Journal of Gastroenterology. 20 (11): 2902–12. doi: 10.3748/wjg.v20.i11.2902 . PMC   3961994 . PMID   24659881.
  54. Boucle, Sebastien; Tao, Sijia; Amblard, Franck; Stanton, Richard A.; Nettles, James H.; Li, Chengwei; McBrayer, Tamara R.; Whitaker, Tony; Coats, Steven J.; Schinazi, Raymond F. (September 2015). "Design, synthesis and evaluation of novel anti-HCV molecules that deliver intracellularly three highly potent NS5A inhibitors". Bioorganic & Medicinal Chemistry Letters. 25 (17): 3711–3715. doi:10.1016/j.bmcl.2015.06.031. PMC   4538959 . PMID   26099532.
  55. 1 2 Romine, Jeffrey L.; St. Laurent, Denis R.; Leet, John E.; Martin, Scott W.; Serrano-Wu, Michael H.; Yang, Fukang; Gao, Min; O’Boyle, Donald R; Lemm, Julie A.; Sun, Jin-Hua; Nower, Peter T.; Huang, Xiaohua (Stella); Deshpande, Milind S.; Meanwell, Nicholas A.; Snyder, Lawrence B. (10 March 2011). "Inhibitors of HCV NS5A: From Iminothiazolidinones to Symmetrical Stilbenes". ACS Medicinal Chemistry Letters. 2 (3): 224–229. doi:10.1021/ml1002647. PMC   4017990 . PMID   24900306.
  56. Shi, Junxing; Zhou, Longhu; Amblard, Franck; Bobeck, Drew R.; Zhang, Hongwang; Liu, Peng; Bondada, Lavanya; McBrayer, Tamara R.; Tharnish, Phillip M.; Whitaker, Tony; Coats, Steven J.; Schinazi, Raymond F. (May 2012). "Synthesis and biological evaluation of new potent and selective HCV NS5A inhibitors". Bioorganic & Medicinal Chemistry Letters. 22 (10): 3488–3491. doi:10.1016/j.bmcl.2012.03.089. PMC   7732024 . PMID   22507961.
  57. Strahotin, Cristina Simona; Babich, Michael (2012). "Hepatitis C Variability, Patterns of Resistance, and Impact on Therapy". Advances in Virology. 2012: 267483. doi: 10.1155/2012/267483 . PMC   3407602 . PMID   22851970.
  58. Owens, Christopher M.; Brasher, Bradley B.; Polemeropoulos, Alex; Rhodin, Michael H. J.; McAllister, Nicole; Wong, Kelly A.; Jones, Christopher T.; Jiang, Lijuan; Lin, Kai; Or, Yat Sun (October 2016). "Preclinical and Clinical Resistance Profile of EDP-239, a Novel Hepatitis C Virus NS5A Inhibitor". Antimicrobial Agents and Chemotherapy. 60 (10): 6216–6226. doi:10.1128/AAC.00815-16. PMC   5038316 . PMID   27503644.
  59. 1 2 3 Feld, Jordan J.; Foster, Graham R. (October 2016). "Second generation direct-acting antivirals – Do we expect major improvements?". Journal of Hepatology. 65 (1): S130–S142. doi: 10.1016/j.jhep.2016.07.007 . PMID   27641983.