Sequence analysis of the NS5A protein of European hepatitis C virus 1b isolates and relation to interferon sensitivity.

Duverlie, Gilles; Khorsi, Hafida; Castelain, Sandrine; Jaillon, Olivier; Izopet, Jacques; Lunel, F.; Eb, F.; Pénin, François; Wychowski, Czeslaw

doi:10.1099/0022-1317-79-6-1373

Cited by 139 publications

(135 citation statements)

References 34 publications

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“…This sequence has been termed the interferon sensitivity-determining region (ISDR). These results were then confirmed by other Japanese studies [11][12][13][14][15] , but were never in accordance with most Western European [16][17][18][19][20] and American studies [21][22][23] , in which most of the ISDR sequences harbored an intermediate profile.…”

Section: Introductionsupporting

confidence: 80%

“…HCV genotype 1, particularly genotype 1b, are most resistant to combined IFN-R therapy [5] . Among viral factors, genetic variability has been studied in many regions of the HCV genome, mainly in hypervariable region 1 (HVR1) and PKR-eIF2α phosphorylation homology domain (PePHD) of E2 region and in PKRbd (including ISDR) of NS5A [17,22,[39][40][41][42][43] . However, few reports have studied the complete NS5A region [17,22] .…”

Section: Variability In Six Different Regions Along the Ns5a Genementioning

confidence: 99%

“…The fulllength NS5A gene was amplified by nested RT-PCR. RT was combined with the first round of PCR with outer primers E1 and E2 while second amplification was performed with inner primers I3 and I4 as previously described (Table 1) [17,31] . PCR products were then subjected to electrophoresis in a 1% agarose gel (NuSieve GTG, FMC) and visualized by ethidium bromide staining before purification.…”

Section: Rna Extraction and Amplification By Rt-pcrmentioning

confidence: 99%

“…Furthermore, a n o t h e r d o m a i n i n t h e N S 5 A r e g i o n , n a m e d V 3 (NS5A2356-2379) [26] , could also be linked to IFN resistance. It has been suggested that mutations in the V3 domain may correlate with IFN response [17] . However, two reports have shown that insertion and deletion around the ISDR and the V3 domain had no impact on HCV RNA replication in cell culture [27,28] .…”

Section: Introductionmentioning

confidence: 99%

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Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy

Veillon

Payan²,

Guillou‐Guillemette³

et al. 2007

WJG

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AIM:To evaluate the implication of substitutions in the hepatitis C virus (HCV) non-structural 5A (NS5A) protein in the resistance of HCV during mono-interferon (IFN) or combined IFN-ribavirin (IFN-R) therapy. Although NS5A has been reported to interact with the HCV RNAdependent RNA polymerase, NS5B, as well as with many cellular proteins, the function of NS5A in the life cycle of HCV remains unclear.METHODS: HCV quasispecies were studied by cloning and sequencing of sequential isolates from patients infected by HCV genotype 1b. Patients were treated by IFN-α2b for 3 mo followed by IFN-α2b alone or combined IFN-R therapy for 9 additional months. Patients were categorized intro two groups based on their response to the treatments: 7 with sustained virological response (SVR) (quasispecies = 150) and 3 non-responders (NR) to IFN-R (quasispecies = 106). RESULTS:Prior to treatment, SVR patients displayed a lower complexity of quasispecies than NR patients. Most patients had a decrease in the complexity of quasispecies during therapy. Analysis of amino acids substitutions showed that the degree of the complexity of the interferon sensitivity-determining region (ISDR) and the V3 domain of NS5A protein was able to discriminate the two groups of patients. Moreover, SVR patients displayed more variability in the NS5A region than NR patients. CONCLUSION:These results suggest that detailed molecular analysis of the NS5A region may be important for understanding its function in IFN response during HCV 1b infection.

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Section: Introductionsupporting

confidence: 80%

Section: Variability In Six Different Regions Along the Ns5a Genementioning

confidence: 99%

Section: Rna Extraction and Amplification By Rt-pcrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy

Veillon

Payan²,

Guillou‐Guillemette³

et al. 2007

WJG

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“…This might suggest that other viral factors, such as HCV genetic changes other than the ISDR 56 or host factors, 51 might have a more profound influence on the outcome of interferon therapy in cases in which NS5A is not divergent. Recent studies from other areas of Europe confirmed the correlation between NS5A mutations and interferon sensitivity showing the comparative frequency of the HCV-1b mutant types as seen in Japan.…”

Section: Discussionmentioning

confidence: 99%

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection

et al. 1999

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An association has been reported between mutations in the amino acid residues 2209-2248 of the nonstructural protein 5A (NS5A) gene (interferon-sensitivity determining region [ISDR]) and interferon efficacy in hepatitis C virus (HCV)-1b infection. This relationship was analyzed in chronic HCV-2 infection. Forty patients with HCV-2a and 35 with HCV-2b were treated with interferon alfa for 6 months with a total dose of 468 to 860 million units. Pretreatment NS5A sequences were determined by direct sequencing. A higher complete and sustained response rate was observed in HCV-2a than in HCV-2b (70% vs. 34%; P ‫؍‬ .003). Serum HCV-RNA levels were lower in complete responders than nonresponders in HCV-2a (P ‫؍‬ .049) and HCV-2b (P ‫؍‬ .02). The number of amino acid mutations was greater in complete responders than nonresponders in NS5A2193- The current primary therapy for chronic hepatitis C is parenteral administration of type 1 interferons (interferon alfa and beta), while the rate of sustained and complete responses with virus eradication is obtained in only up to 30% of the patients. 1-3 To date, hepatitis C virus (HCV) is classified into at least 9 major genotypes and more than 30 subtypes. 4,5 In Japan, about 70% of the patients with chronic hepatitis C are infected with HCV genotype 1b (HCV-1b), and the rest are infected with HCV genotype 2 (HCV-2) 6 (25% with HCV-2a and 5% with HCV-2b). While the complete response is as low as 10% to 20% in HCV-1b infection, it is considered more than 60% in HCV-2 infection in Japan. [7][8][9][10][11][12] Such differences in interferon efficacy among various HCV genotypes suggest that a certain kind of genetic change of the virus could affect the sensitivity to interferon.We recently identified a region that is associated with the response to interferon in HCV-1b genomes in Japan. 13 An increase in the number of amino acid changes in the nonstructural protein 5A gene (NS5A) (NS5A2209-2248, interferon sensitivity determining region [ISDR]) makes HCV more sensitive to interferon. 14 However, the mechanism of the different response to interferon therapy among patients with HCV-2 infection is still unclear. Some studies suggested that a lower viral load is associated with the good response to interferon in HCV-1b or non-1b, 12,15 the mechanism of which is still unknown. In previous studies, interferon effect and pretreatment viral load were also associated with the mutations in ISDR in HCV-1b. 13,16 Thus, the relation between NS5A structure and interferon effect or viral load in HCV genotypes other than HCV-1b is of great interest.Several studies that focused on biological functions of NS5A revealed some aspects of its properties. In particular, Gale et al. 17 suggested that the NS5A protein inhibits an RNA-dependent protein kinase (PKR), which plays a major role in the viral protection by inhibiting viral protein translation. The NS5A protein of HCV-1b and -1a forms a complex with the PKR and inhibits the phosphorylation of eukaryotic translation initiation factor-2 (eIF-2). Mor...

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The NS5a gene of hepatitis C virus in patients treated with interferon-?

2000

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Patients infected with hepatitis C virus (HCV) genotype 3 have a better response to interferon-alpha (IFN-alpha) therapy than those infected with genotype 1. There are extensive sequence differences between genotypes in the 3' half of the NS5a gene. An association between IFN-alpha response and the interferon sensitivity-determining region (ISDR) (amino acids 2209-2248) of HCV genotype 1b has been described [Enomoto et al. (1996) New England Journal of Medicine 334:771-776]. A prospective study was conducted to determine whether the derived NS5A amino acid sequence or quasi-species diversity could predict response to IFN-alpha therapy. Serum samples were obtained before, during, and after treatment from 35 IFN-alpha-treated patients chronically infected with HCV (eight with type1b,13 with type1a, and 14 with type3a). Nucleotide sequences were determined, and amino acid sequences corresponding to residues 2178-2390 of the polyprotein were derived. Quasi-species complexity was analysed by amplification of the ISDR region (2270-2403), followed by single-stranded conformation polymorphism (SSCP). No amino acid sequence that could be used to predict response to treatment was found, and there was no selection of specific amino acid residues during treatment. A striking lack of variability was seen in HCV genotype 3a, but the small degree of variation could suggest an effect on response. SSCP showed that variation in the predominant NS5a sequence occurred in the presence and absence of therapeutically administered IFN-alpha. HCV quasi-species diversity pretreatment did not predict IFN-alpha treatment outcome. The conclusion of the study is that the amino acid sequence of NS5a cannot be used to predict the efficacy of treatment with IFN-alpha in HCV-infected patients in Scotland. No evidence was found to support the selection of IFN-alpha-resistant strains in the NS5a gene.

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Sequence analysis of the NS5A protein of European hepatitis C virus 1b isolates and relation to interferon sensitivity.

Cited by 139 publications

References 34 publications

Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy

Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection

The NS5a gene of hepatitis C virus in patients treated with interferon-?

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