Clinical application of the Quantiplex HCV RNA 2.0 and Amplicor HCV Monitor assays for quantifying serum hepatitis C virus RNA

Genetic variation of hepatitis C virus in a cohort of injection heroin users in Wuhan, China

Since the majority of heroin abusers use injection as the primary route of admission, heroin abuse contributes significantly to the transmission of hepatitis C virus (HCV). We determined HCV infection and its genotype distribution among injection heroin users in Wuhan, the largest city in the central China. Eight hundred seventy-eight (84%) out of 1046 serum specimens from the injection drug users were positive for HCV antibody. Out of randomly selected 122 specimens positive for HCV antibody, seventy-eight (64%) had detectable HCV RNA with genotype 6a as the predominant strain (50%), followed by 3b (32.2%), 1a (8.1%), 1b (6.5%), and 3a (3.2%). HCV RNA levels in male heroin users were significantly higher (P=0.013) than those in the female subjects. Although there was no significant difference in HCV RNA levels among the specimens positive for HCV 6a and 1a/1b, the samples with 6a or 1a/1b contained higher levels of HCV RNA than the specimens positive for HCV 3b (P=0.019, P=0.012, respectively). These findings indicate that there is a high prevalence of HCV infection with genotypes 6a and 3b as predominated strains among injection heroin users in Wuhan, China.

Hepatitis C virus genotypes in southern Taiwan: prevalence and clinical implications

The role of hepatitis C virus (HCV) genotypes in the development of hepatocellular carcinoma (HCC) is still controversial. To determine the distribution and clinical implications of HCV genotypes in southern Taiwan, we analysed 418 patients with chronic HCV infections. HCV genotypes were determined using an HCV Line Probe Assay. The predominant HCV genotype was 1b (45.5%), followed by 2a/2c (30.9%) and 2b (6.9%). The prevalence of genotype 1b in HCC patients (60.3%) was significantly higher than in those with liver cirrhosis (38.7%) and chronic hepatitis (38.7%) (P=0.003 and P<0.001, respectively). Patients with chronic HCV 2a/2c infection had higher alanine aminotransferase (ALT) levels than those with chronic HCV 1b infection (P<0.001). Univariate analysis revealed that disease severity was significantly correlated with older age, genotype 1b, lower ALT levels and lower viral load. Based on multiple logistic regression analysis, after adjusting for age and serum HCV RNA levels, HCV 1b infection was still a significant risk factor for HCC. In conclusion, the predominant genotypes in southern Taiwan were 1b and 2a/2c, and disease severity was associated with genotype 1b.

Treatment of Chronic Hepatitis C in Southern Taiwan

Chronic hepatitis C virus (HCV) infection may lead to cirrhosis and hepatocellular carcinoma. Interferon (IFN)-alpha is effective in the treatment of chronic hepatitis C. The rate of response to IFN is enhanced by increasing the IFN dose. Extending the treatment duration can reduce the relapse rate. Addition of ribavirin to IFN increases the sustained virological response (SVR). Thus, combination therapy with IFN and ribavirin was adopted for the treatment of chronic hepatitis C in Kaohsiung Medical University Hospital in 1998. Approximately 60% of patients receiving IFN/ribavirin therapy gained SVR. IFN 6 million units three times per week combined with daily ribavirin for 6 months achieved SVR more frequently than combination therapy with 3 million units. Factors for SVR in these combination regimens were HCV genotype, viral load and early virological response. Long-term follow-up of patients treated with IFN has shown that SVR might reduce the risk of progression to cirrhosis and hepatocellular carcinoma. Pegylated (peg)-IFN has a longer half-life and better efficacy. Combination therapy with peg-IFN and ribavirin accomplished higher SVR than conventional IFN and ribavirin. A multicenter clinical trial was conducted in Taiwan to compare the efficacy of combination therapy between peg-IFN/ribavirin and conventional IFN/ribavirin for 6 months. SVR was higher in patients receiving peg-IFN and ribavirin, especially in those infected with HCV genotype 1b. Based on the results obtained, the national health insurance started to sponsor the combination therapy in October 2003, with a suggested duration for 6 months. Some small-scale studies in Taiwan have postulated higher SVR for treatment duration of 12 than of 6 months in patients with genotype 1b. Further investigation should be conducted in the near future.

High versus standard doses interferon-alpha in the treatment of naïve chronic hepatitis C patients in Taiwan: a 10-year cohort study

Background

Interferon-alpha monotherapy is effective in less than one-third patients with chronic hepatitis C. The dose-effect, tolerability and durability of interferon-alpha treatment and its long-term effect on the prevention of cirrhosis and hepatocellular carcinoma in naïve Taiwanese patients with chronic hepatitis C have not been well investigated. We conducted the present cohort study treated with high and standard interferon-alpha to illustrate the issues.

Methods

We performed a long-term virologic and histological follow-up of 214 chronic hepatitis C patients treated with interferon-alpha, 3 million units (3-MU, n = 80) or 6-MU (n = 134) thrice weekly for 24 weeks, in Taiwan between 1992 and 2001.

Results

There was no difference in the incidence of discontinuation between 3-MU and 6-MU groups (4/80, 5.0% versus 10/134. 7.5%). The 6-MU group had similar incidence of adverse events with the 3-MU group, except that 6-MU group had significantly higher incidence of psychological manifestations, mainly presented as irritability. The rates of sustained virological response (SVR) were significantly higher in 6-MU regimen (37.1%) than in 3-MU regimen (23.7%, p < 0.05) in per protocol analysis. Based on multivariate analysis, baseline viral load was strongly associated with SVR, followed by hepatitis C virus genotype, interferon-alpha regimen, and liver fibrosis. A histological improvement in necroinflammatory activity, but not in fibrosis was observed in the follow-up biopsy performed 0.5–5.5 years (mean: 1.9 years, n = 51) after end-of-treatment. Among patients without SVR, there was more activity improvement in 6-MU group. The durability of SVR was 100% (18/18) and 97.8% (45/46) for 3-MU and 6-MU group, respectively, in a mean follow-up period of 6.81 years (5.25–9.18 years). For 163 baseline non-cirrhotic patients, 9 of 84 (10.7%) non-responders and 3 of 79 (3.8%) sustained responders progressed to cirrhosis during a mean follow-up period of 5.52 and 5.74 years, respectively (p = 0.067, Kaplan-Meier survival analysis, log-rank test). For all 200 patients, hepatocellular carcinoma was detected in 12 of 113 (10.6%) non-responders and one of 87 (1.1%) sustained responders during a mean follow-up period of 5.67 and 5.73 years, respectively (p < 0.01, Kaplan-Meier survival analysis, log-rank test).

Conclusion

We confirm the dose effect of interferon-alpha in chronic hepatitis C. Six-MU regimen had better efficacy than 3-MU regimen in virologic and histological responses. Both regimens had good tolerability and durability in Taiwan. Sustained response could reduce the incidence of cirrhotic change and hepatocarcinogenesis.

Performance of an automated system for quantitation of hepatitis C virus core antigen

The performance of an automated system for the HCV core antigen assay using the Lumispot LS-2000 automated analyzer was evaluated against that of the COBAS AMPLICOR HCV MONITOR Test, version 2.0 (COBAS HCM-2) for the testing of sera from 155 chronic hepatitis C patients. The within-run coefficient of variations (CVs) and the between-day CVs were <9.6 and <8.4%, respectively. The analytical detection limit of the HCV core antigen assay was 5.0 fmol/l and it was linear up to at least 45000 fmol/l. No blood elements interfered with the assay. HCV core antigen levels were significantly correlated with HCV RNA levels in both serogroup 1 and serogroup 2 (r=0.829, P<0.001). It is estimated that 100 fmol/l of HCV core antigen level was equivalent to approximately 30000 IU/ml of HCV RNA level. Three sera had HCV core antigen levels below the detection limit of the assay and their HCV RNA levels as determined by COBAS HCM-2 assay were very low at 1000, 1100 and 1700 IU/ml, respectively. In six IFN responders among seven patients, HCV core antigen levels were in parallel with HCV RNA levels. In conclusion, since this assay demonstrated good reproducibility, a favorable dynamic range and adequate sensitivity, it may be useful as an alternative direct marker of viral level monitoring in patients with hepatitis C.

Determination of HCV genotype by direct sequence analysis of quantitative PCR products

Hepatitis C virus (HCV) genotyping, combined with quantitative evaluation of HCV RNA, may be beneficial for the management of chronic hepatitis C and in the selection of candidates for interferon treatment. In this study, the COBAS AMPLICOR HCV MONITOR test, a commercially available quantitative assay for HCV RNA, was used. Amplification products obtained from HCV-positive cases were subjected to direct sequencing and genotyping based on seven phylogenetically informative regions within the 5'UTR. Results were compared with those obtained by INNO-LiPA assay. Typing results yielded by both methods were in complete accordance for type and subtype assignment. Twenty-nine of 500 specimens (5.8%) were unclassifiable and belonged to samples with a titer of <70.000 IU, as determined by quantitative assay. Despite this limitation, the overall gain in efficiency, the low rate of test failure and a better resolution of mixed genotypes all constitute a considerable advantage of this system over the commercial hybridization technique for routine clinical laboratory use.

Quantitative assay of hepatitis C virus RNA using an automated extraction system for specific capture with probes and paramagnetic particle separation

A commercially available automated specimen preparation instrument for specific probe capture and paramagnetic separation has been developed (AmpliCap/GT-12; Roche Molecular Systems). We evaluated assay performance of the AmpliCap/GT-12 in the quantitative assay for hepatitis C virus (HCV) RNA with the AMPLICOR HCV MONITOR Test (version 2.0). Assay linearity using serial dilutions from a serum panel was observed in the range of 500 to 850000 IU/ml, with a slightly compromised slope in the higher viral titers. The overall within-run and between-run reproducibility of the entire detection process for 3 and 5 log(10) (IU/ml) of HCV RNA in samples had a standard deviation of <0.2, which was comparable to a manual method based on organic extraction and isopropanol precipitation (Roche Molecular Systems). Comparison of the test results with those obtained by the manual method showed a good correlation (R(2) = 0.972, n = 86). Using heparin (3, 6.5, and 13 U/ml), dextran sulfate (0.1, 1, and 5 mM), hemoglobin (1.13, 2.25, and 4.5 g/liter), conjugated or unconjugated bilirubin (7.5, 15, and 30 mg/dl), and ATP (1.25, 2.5, and 5.0 mM) as known inhibitors, inhibition was only detected at a dextran sulfate concentration of 1 mM with the manual method but not with the AmpliCap/GT-12 extraction. In summary, the AmpliCap/GT-12 system was shown to permit a stable extraction process and accurate results for the quantitative assay of HCV RNA, successfully eliminating the inhibitory effect of dextran sulfate. This automated extraction system provides reliable and reproducible test results and saves labor; thus, it is suitable for routine diagnostic PCR.

Quantitation of hepatitis C virus RNA by third generation branched DNA-based signal amplification assay

Quantitation of hepatitis C virus (HCV) RNA has become an important tool in different clinical settings and is used extensively for pretreatment evaluation of patients infected chronically with HCV. In this study, the performance characteristics of the third generation branched DNA-based signal amplification assay (bDNA 3.0) for HCV RNA quantitation were established. The new assay version showed an analytical specificity of 98%. Mean intra- and between-run imprecisions were 6.8 and 11.2%, respectively. The assay was linear over its entire dynamic range. Quantitation appeared to be unaffected by the genotypic variability of HCV. A comparison of bDNA 3.0 with the second generation bDNA assay calibrated against the international WHO HCV RNA standard, and the PCR-based Cobas Amplicor HCV Monitor 2.0 revealed a fairly good correlation among the assays. Twenty-nine and 11% of the paired quantitative results differed by more than log(10)0.5 (i.e. three-fold). All three assays after calibration against the WHO standard also yielded clinically comparable results with regard to the tailoring of interferon alpha/ribavirin treatment duration in patients infected by HCV genotypes 1, 4, and 5.

Detection of residual hepatitis C virus RNA by transcription-mediated amplification in patients with complete virologic response according to polymerase chain reaction-based assays

A considerable proportion of patients with chronic hepatitis C who achieve a virologic end-of-treatment response relapse after discontinuation of therapy. It is conceivable that polymerase chain reaction (PCR)-based assays with a lower detection limit of 100 to 1, 000 hepatitic C virus (HCV) RNA copies/mL are still too insensitive to detect residual viremia. End-of-treatment serum samples of 47 patients with a virologic relapse according to results of qualitative PCR assays (Amplicor HCV; Roche Molecular Systems, Mannheim, Germany) were tested by transcription-mediated amplification (TMA), an isothermal, autocatalytic target amplification method that has the potential to detect less than 50 HCV RNA copies/mL. Virologic sustained responders (n = 59) and nonresponders (n = 49) served as controls. In end-of-treatment serum samples of virologic sustained responders and nonresponders an almost complete concordance between PCR and TMA results was observed (98%). However, HCV RNA was detectable by TMA in end-of-treatment serum samples from 16 of 25 relapse patients (64%) who were HCV-RNA-negative according to Amplicor HCV version 1.0 (lower detection limit 1,000 copies/mL) and in 8 of 22 patients (36%) who were HCV-RNA-negative according to Amplicor HCV version 2.0 (lower detection limit 100 copies/mL). End-of-treatment alanine transaminase (ALT) levels of sustained virologic responders and TMA-negative relapsers were similar, whereas a trend toward higher ALT values was observed in TMA-positive relapsers compared with sustained virologic responders (P = 0.09). In conclusion, HCV RNA can be detected at the end of treatment by TMA in a considerable proportion of patients who were classified as virologic end-of-treatment responders with a subsequent virologic relapse according to PCR-based methods.

Clinical evaluation of the automated COBAS AMPLICOR HCV MONITOR test version 2.0 for quantifying serum hepatitis C virus RNA and comparison to the quantiplex HCV version 2.0 test

A second-generation hepatitis C virus (HCV) quantitative assay (COBAS AMPLICOR HCV MONITOR Test, version 2.0; COBAS HCM-2) has been developed, with the intention of achieving equivalent quantification of all HCV genotypes and improving assay performance. To evaluate the clinical performance of COBAS HCM-2 and its utility in predicting the response to alpha interferon treatment, sera from 215 chronic hepatitis C patients were analyzed and the results were compared with those obtained by the Quantiplex bDNA HCV RNA, version 2.0, assay (bDNA-2). The COBAS HCM-2 had significantly greater sensitivity than bDNA-2 (94.9 versus 88.4%; P < 0.001) when performed with sera from chronic hepatitis C patients who were viremic by a qualitative PCR test. The standard deviations for the within-run and between-run reproducibilities of COBAS HCM-2 were <0. 1 and <0.2, respectively, and it showed an improved linear range between genotypes with the threefold serial dilutions tested (r(2) = 0.986 to 0.995). The COBAS HCM-2 results were positively correlated with the bDNA-2 results, but the values for COBAS HCM-2 were on average 0.96 log lower than the values for bDNA-2. The mean difference in quantification values between these two assays did not differ among samples with different genotypes (0.70 to 1.00 log). No genotype-dependent difference in viral load was observed. The pretreatment viral load was significantly lower in complete responders. By using multivariate analysis, the viral load 2 weeks after the initiation of alpha interferon treatment was the strongest predictor of a complete response. In conclusion, COBAS HCM-2 demonstrated good sensitivity, linearity, and reproducibility and efficiency equal to that of bDNA-2 for the quantification of HCV genotypes 1 and 2. Hence, this assay provides a rapid and reliable method for the quantification of HCV RNA in serum and is useful for the planning of interferon treatment.