Accurate quantification of hepatitis C virus (HCV) RNA from all HCV genotypes by using branched-DNA technology

Detmer, Jill; Lagier, Robert; Flynn, Jacqueline K.; Zayati, C; Kolberg, Janice A.; Collins, Mark L.; Urdea, M. S.; Sánchez-Pescador, Ray

doi:10.1128/jcm.34.4.901-907.1996

Cited by 226 publications

(97 citation statements)

References 52 publications

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“…Each sample was tested for routine biochemical parameters. The HCV RNA level was analyzed by improved branched chain amplification technology (HCV RNA 2.0 assay, Chiron Corp., Emeryville, CA), 33 and the results were expressed as genomic equivalents per milliliter (eq/mL), with 10 6 eq/mL expressed as 1 Meq/mL. The lower limit of detection of the assay was 0.2 ϫ 10 6 eq/mL (0.2 Meq/mL).…”

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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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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“…This newer version has been shown to accurately quantitate HCV RNA from all genotypes. 16,17 HCV genotype was determined by restriction fragment length polymorphism based at the 5Ј-untranslated genomic region. 18,19 The nomenclature of HCV genotypes was according to the system proposed by Simmonds et al 20 Liver Histology.…”

Section: Patients Betweenmentioning

confidence: 99%

Intrahepatic hepatitis C virus-specific cytotoxic T lymphocyte activity and response to interferon alfa therapy in chronic hepatitis C

et al. 1998

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Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) have been shown to play a role in host defense and pathogenesis of chronic HCV infection. Our aim was to test the hypothesis that intrahepatic HCV-specific CTL activity may impact subsequent response to interferon alfa (IFN-␣) therapy. Of the 37 patients that we have prospectively evaluated for HCV-specific CTL activity in liver, 21 received IFN therapy, and 19 completed a 6-month course and attended 6 to 18 months of follow-up. Intrahepatic CD8 ؉ cells were isolated from liver biopsy tissue and tested against target cells expressing HCV antigens to determine intrahepatic CTL activity. The relationship between treatment response and HCV-specific CTL activity and other factors known to associate with response (genotype, viremia, histology) was analyzed. HCV-specific CTL activity was detected in 9 of 21 patients (and 9 of 19 who completed therapy). After 6 months of IFN therapy, 8 of 19 (42%) patients had normal serum alanine transaminase (ALT) (complete responders). After 18 months of follow-up, only 3 patients (16%) had a sustained biochemical response. Of the 9 patients with detectable HCV-specific CTL activity in their liver before treatment, 7 (78%) developed a complete response. In contrast, only 1 of the 10 patients with no detectable HCV-specific CTL activity developed a complete response to IFN (P F .01). In 6 of 8 patients with a complete response, including the 3 sustained responders, the CTL response appeared to be directed predominately to the HCV core region. These data suggest that the host immune response, particularly that mediated by CD8 ؉ CTL, may be important in determining the outcome of IFN therapy for chronic HCV infection. Further understanding of the mechanism of action of IFN should impact the design of better therapeutic strategies against chronic HCV infection. (HEPATOLOGY 1998;28:225-230.)The host cellular immune defense, including the CD4 ϩ and CD8 ϩ T-cell response, is activated in patients with hepatitis C virus (HCV) infection. The intensity of the T-cell response during the early stages of infection may be a critical determinant of disease resolution and control of infection. 1,2 In chronic viral infection, viral-specific CD8 ϩ cytotoxic T lymphocytes (CTL) have been shown to be important in host defense and in the control of the viral infection. [3][4][5][6][7] In lymphocytic choriomeningitis virus infection, virus-specific CTL activity reduces viral titers by 4 to 5 logs. 8 It is felt that CTL might lead to viral clearance through either direct lysis of infected cells or cytokine-mediated mechanisms. We and others have shown that HCV-specific CTL activity is detectable in the liver in a proportion of patients with chronic HCV infection. The presence of HCV-specific CTL activity in bulk-expanded CTL was found to be associated with a lower level of viremia and a greater inflammatory activity in the liver, suggesting that HCV-specific CTLs may assist in the control HCV infection, but, in so doing, contribute to hepatoce...

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“…As shown in the present study, 204 (95.8%) of 213 cases were detectable by the second-generation assay, providing evidence that sensitivity was indeed significantly improved. The sensitivity of this assay was comparable with that of the COBAS v2.0 assay, a well-calibrated, sensitive and non-serotype-dependent assay (8,(17)(18)(19)(20)(24)(25)(26).…”

Section: Figmentioning

confidence: 72%

Evaluation of clinical usefulness of second‐generation HCV core antigen assay: comparison with COBAS AMPLICOR HCV MONITOR assay version 2.0

Yokosuka

Kawai

Suzuki

et al. 2005

Liver International

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Accurate quantification of hepatitis C virus (HCV) RNA from all HCV genotypes by using branched-DNA technology

Cited by 226 publications

References 52 publications

Association of Amino Acid Sequence in the Pkr–Eif2 Phosphorylation Homology Domain and Response to Interferon Therapy

Association of Amino Acid Sequence in the Pkr–Eif2 Phosphorylation Homology Domain and Response to Interferon Therapy

Intrahepatic hepatitis C virus-specific cytotoxic T lymphocyte activity and response to interferon alfa therapy in chronic hepatitis C

Evaluation of clinical usefulness of second‐generation HCV core antigen assay: comparison with COBAS AMPLICOR HCV MONITOR assay version 2.0

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