Genotypic subtyping of hepatitis C virus

Chayama, Kazuaki; Tsubota, Akihito; Arase, Yasuji; Saitoh, Satoshi; Koida, Isao; Ikeda, Kenji; Matsumoto, Toyomi; Kobayashi, Mariko; Iwasaki, Satomi; Koyama, Shima; Morinaga, Tsuto; Kumada, Hiromitsu

doi:10.1111/j.1440-1746.1993.tb01507.x

Cited by 158 publications

(100 citation statements)

References 26 publications

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“…HCV genotyping was determined by amplification of specific gene fragments from both the core 26 and NS5 regions of the genome. 27 The distribution of HCV genotypes among the 52 patients was similar to that of the U.S. population. 30 There was a higher percentage of genotype 1a in the NR group, which is consistent with previous reports showing that this genotype is relatively poorly responsive to interferon therapy.…”

Section: Resultsmentioning

confidence: 67%

Effect of interferon therapy on hepatitis C virus RNA in whole blood, plasma, and peripheral blood mononuclear cells

Schmidt¹,

Wu²,

Brashear³

et al. 1998

Hepatology

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Fifty-two patients with chronic hepatitis C virus (HCV)infection were treated with standard doses of interferon alfa-2b. During treatment, HCV RNA detection was studied in samples of whole blood (WB), plasma (Pl), and peripheral blood mononuclear cells (PBMCs). Individuals were classified as sustained responders (SRs), complete responders with relapse (CRs), partial responders (PRs), or nonresponders (NRs) according to normalization of serum alanine transaminase (ALT) during treatment and follow-up. Before treatment, 100% of WB samples and more than 95% of Pl and PBMC samples were positive for HCV RNA. During treatment, there was progressive clearance of HCV RNA from Pl and PBMCs in SRs and CRs, but CRs had significantly more positive WB samples during and following treatment (P Ͻ.0001). At 6 months, only 10% of CR patients were positive by Pl assay, but 50% were positive by WB assay (P Ͻ.01). In the PR group, all WB samples remained positive throughout treatment, although 25% to 40% of PBMC and Pl samples became negative for HCV RNA during the first 2 months of therapy (WB Ͼ Pl or PBMC; P Ͻ .001). However, at later times during treatment most Pl and PBMC samples in the PR group were positive. Samples from the NR group showed no clearance of HCV RNA from WB, Pl, or PBMC fractions. These data document the increased sensitivity of WB assays for detecting HCV RNA in the peripheral blood of patients during interferon therapy. Furthermore, our findings suggest that WB analysis of HCV RNA may be a useful parameter to monitor in determining the end point of interferon therapy.(HEPATOL-OGY 1998;28:1110-1116.)Hepatitis C virus (HCV) is a small, enveloped RNA virus of approximately 9,500 nucleotides that is responsible for more than 90% of parenterally transmitted cases of non-A, non-B hepatitis. 1-3 Infection with HCV usually results in chronic active hepatitis, which may progress to cirrhosis. Currently, end-stage liver disease resulting from chronic HCV infection is a major reason for referral of patients for orthotopic liver transplantation in the United States. 4,5 Interferon therapy is the only approved treatment for chronic hepatitis C. Approximately 50% of patients who are treated respond with normalization of serum aminotransferase levels, although more than half of these responders will relapse after discontinuation of the drug. Thus, approximately 20% of treated patients have a durable, sustained response. 6,7 Although the reasons responsible for relapse are unclear, variables such as length of treatment, HCV genotype, and histological evidence of inflammation and fibrosis at the start of therapy appear to correlate with treatment outcomes. 3,[8][9][10][11] Reverse-transcription (RT) polymerase chain reaction (PCR) techniques to detect HCV RNA during interferon therapy have been widely employed and are considered to be important for optimum management. 12,13 A high level of HCV RNA in serum before treatment is a poor prognostic sign for sustained response; unfortunately, clearance of virus from serum or plasma ...

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Section: Resultsmentioning

confidence: 67%

Effect of interferon therapy on hepatitis C virus RNA in whole blood, plasma, and peripheral blood mononuclear cells

Schmidt¹,

Wu²,

Brashear³

et al. 1998

Hepatology

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“…All patients had an abnormal alanine transaminase level (ALT) for more than 6 months, chronic active hepatitis confirmed by tissue biopsy and histopathological examination, and were positive for genotype 1b HCV on PCR-based genotyping. 32 All patients were negative for HBs antigen and serological markers for human immunodeficiency virus, and did not receive immunosuppressive or antiviral therapy within 6 months before IFN therapy.…”

Section: Patientsmentioning

confidence: 99%

Association of Amino Acid Sequence in the PKR-eIF2 Phosphorylation Homology Domain and Response to Interferon Therapy

et al. 2000

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Hepatitis C virus (HCV) usually causes chronic infection, which can result in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. [1][2][3][4] The only drug that effectively reduces the virus load is interferon (IFN), but complete eradication of the virus occurs in only some treated patients. [5][6][7][8] Currently, genotype 1b and a high virus titer are well-established predictive factors of a poor response to IFN. 9-11 Enomoto et al., 12,13 recently reported that amino-acid-sequence substitutions in a 40 amino acid stretch (codons 2209-2248) in the NS5A region of HCV genotype 1b are tightly associated with the outcome of IFN therapy, and designated this region as the IFN-sensitivity-determining-region (ISDR). A recent in vitro study by Gale et al., 14,15 suggested that the ISDR (or the amino-acid stretch adjacent to it) binds to IFN-inducible protein kinase (PKR), and inhibits its action as a blocker of viral protein synthesis. However, whether this region is really predictive of the outcome of IFN therapy is still controversial. A few Japanese studies have confirmed the fact that HCV virus with multiple amino-acid substitutions in this region is sensitive to IFN, [16][17][18][19] but studies from Europe and the United States have reported that such an association was not observed in their patients. [20][21][22][23][24][25][26][27][28] One recent study from Europe did however show the partial predictive value of amino-acid analysis in the ISDR. 29,30 More recently, Taylor et al. 31 reported that HCV E2 protein contains a 12 amino-acid-sequence domain that is highly homologous to the autophosphorylation site of PKR and initiation factor eIF2 ␣, a target of PKR (the PKR-eIF2 ␣ phosphorylation homology domain [PePHD]). They showed that the E2 protein inhibited the kinase activity of PKR and blocked its inhibitory effect on protein synthesis and cell growth, suggesting that the interaction of E2 and PKR may be one of the mechanisms by which HCV circumvents the antiviral effect of IFN. They also reported that E2 proteins with a PePHD sequence identical to genotypes 2 and 3 HCV, which are known IFN-sensitive genotypes, showed only a weak inhibitory effect against PKR activity.The above results prompted us to investigate whether aminoacid substitutions in the PePHD domain correlate with outcome of IFN therapy in patients with genotype 1b HCV infection. Furthermore, we sequenced multiple clones of PePHD in patients before and during IFN to investigate the behavior of HCV quasispecies in this region and to determine whether an IFN-resistant strain was selected during IFN treatment. We also studied amino-acid sequences of the ISDR and virus load in the same population using 3 different quantitative measurements of HCV, namely, branched (b)DNA assay and real time Abbreviations: ALT, alanine transaminase; HCV, hepatitis C virus; ISDR, interferon sensitivity determining region; PCR, polymerase chain reaction, PePHD, PKR-eIF2 ␣ phosphorylation homology domain; RT, reverse transcription; PKR, IFN-inducible prot...

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“…At present PCR-based methods are the principal means by which variants of HCV may be identified (Okamoto et al, 1992c;Stuyver et al, 1993a;Chayama et al, 1993;. The major drawbacks of PCR-based methods, however, are the expense and complexity of the procedure which makes difficult the processing of large numbers of clinical samples on a routine basis.…”

Section: Introductionmentioning

confidence: 99%

Use of NS-4 peptides to identify type-specific antibody to hepatitis C virus genotypes 1, 2, 3, 4, 5 and 6

Bhattacherjee

Prescott²,

Pike³

et al. 1995

Journal of General Virology

131

100

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The 5' end of the NS-4 protein of different genotypes of hepatitis C virus (HCV) is highly variable in nucleotide and inferred amino acid sequence, with frequent predicted amino acid substitutions between all six of the major HCV genotypes described to date. This region has been shown to be antigenic by epitope mapping, and elicits antibody in HCV-infected individuals with a detectable type-specific component. We have used this sequence data to specify branched peptides for an indirect binding/competition assay to detect typespecific antibody to each major genotype. A total of 183 out of 210 samples (87%) from blood donors and patients with chronic hepatitis C infected with genotypes 1 to 6 showed detectable type-specific antibody to NS-4 peptides that in almost all cases (> 97 %) corresponded to the genotype detected by a PCR typing method. These findings demonstrate the existence of major antigenic differences between genotypes of HCV, and indicate how infection with different variants of HCV may be detected by a serological test.

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Genotypic subtyping of hepatitis C virus

Cited by 158 publications

References 26 publications

Effect of interferon therapy on hepatitis C virus RNA in whole blood, plasma, and peripheral blood mononuclear cells

Effect of interferon therapy on hepatitis C virus RNA in whole blood, plasma, and peripheral blood mononuclear cells

Association of Amino Acid Sequence in the PKR-eIF2 Phosphorylation Homology Domain and Response to Interferon Therapy

Use of NS-4 peptides to identify type-specific antibody to hepatitis C virus genotypes 1, 2, 3, 4, 5 and 6

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