Comparison of three commercially available assays for HCV RNA using the international unit standard: implications for management of patients with chronic hepatitis C virus infection in clinical practice

Hepatitis C virus: Virology, diagnosis and treatment

More than twenty years of study has provided a better understanding of hepatitis C virus (HCV) life cycle, including the general properties of viral RNA and proteins. This effort facilitates the development of sensitive diagnostic tools and effective antiviral treatments. At present, serologic screening test is recommended to perform on individuals in the high risk groups and nucleic acid tests are recommended to confirm the active HCV infections. Quantization and genotyping of HCV RNAs are important to determine the optimal duration of anti-viral therapy and predict the likelihood of response. In the early 2000s, pegylated interferon plus ribavirin became the standard anti-HCV treatment. However, this therapy is not ideal. To 2014, boceprevir, telaprevir, simeprevir, sofosbuvir and Harvoni are approved by Food and Drug Administration for the treat of HCV infections. It is likely that the new all-oral, interferon-free, pan-genotyping anti-HCV therapy will be available within the next few years. Majority of HCV infections will be cured by these anti-viral treatments. However, not all patients are expected to be cured due to viral resistance and the high cost of antiviral treatments. Thus, an efficient prophylactic vaccine will be the next challenge in the fight against HCV infection.

Rapid detection of hepatitis C virus RNA by a reverse transcription loop-mediated isothermal amplification assay

The usefulness of reverse transcription loop-mediated isothermal amplification (RT-LAMP) for the rapid diagnosis of hepatitis C virus (HCV) RNA was evaluated. This assay showed higher sensitivities than that of nested RT-PCR, with a detection limit of 600 IU mL(-1) , and no cross-reactivity was observed with hepatitis A virus, hepatitis B virus and hepatitis E virus. Furthermore, 106 stored sera from recently diagnosed cases were retrospectively investigated with real-time RT-PCR, the nested RT-PCR, in parallel with this new assay. The general detection rates of HCV RT-LAMP, real-time PCR and the nested RT-PCR for 106 stored sera samples were 95%, 96% and 88%, respectively. This study provides the first data on the usefulness of HCV RT-LAMP in the diagnosis of HCV RNA, especially in the early clinical diagnosis of acute HCV infection.

Quantification of hepatitis C virus (HCV) RNA in a multicenter study: implications for management of HCV genotype 1-infected patients

Assessment of the viral load in hepatitis C virus (HCV) genotype 1-infected patients is critical before, during, and after antiviral therapy. In patients achieving a rapid virological response at week 4 of treatment, the viral load at the baseline is considered a predictive criterion of a sustained virological response 24 weeks after the discontinuation of treatment. A >or=2-log(10) drop in the viral load at week 12 of treatment (early virological response) triggers the continuation of therapy. We organized a multicenter study (MS) for diagnostic laboratories involved in the quantification of HCV RNA. Commercial assays, including two based on real-time reverse transcription-PCR (TaqMan system), and in-house methods, were used by the 61 participants. The overall reproducibility of the commercial quantitative nucleic acid amplification techniques (qNAT) was acceptable. As the intermethod variability among commercial qNAT for HCV RNA was still present, the manufacturers of these test kits should join efforts to harmonize the means of quantification of HCV RNA. This study also shows that caution should be exercised when the baseline viral load is evaluated and when the 2-log(10) reduction after 12 weeks of therapy is interpreted. Finally, this MS confirms the higher sensitivity of the commercial qNAT based on the TaqMan system, making them the elective assays for the monitoring of therapy.

Expert opinion on the treatment of patients with chronic hepatitis C

The current preferred treatment for patients with hepatitis C virus (HCV) is combination therapy consisting of pegylated interferon alfa and ribavirin (RBV) for 24-48 weeks. Although this approach appears to be highly effective for patients with HCV genotypes 2 or 3, who have a sustained virological response (SVR) of approximately 80%, the treatment algorithm is less effective for patients with HCV genotype 1, as these patients have SVR rates of just 40-50%. In order to improve treatment outcomes, this article explores potential approaches for the optimization of treatment for patients with HCV genotype 1: considering shorter treatment periods for patients with a rapid virological response (RVR), increasing treatment periods for slow responders, and increasing RBV dose are all suggestions. Results from clinical trials suggest that approximately 20% of the HCV genotype 1-infected population are slow responders, and around 15% of all HCV genotype-1 infected patients could benefit from a shorter treatment duration without compromising the SVR rate. Interest has also focused on whether treatment duration could be individualized in some patients with genotype 2 and 3 infection. Here all the findings from recent studies are translated into practical advice, to help practitioners make evidence-based treatment decisions in everyday clinical practice. Although there are areas where currently available data do not provide conclusive evidence to suggest amending treatment approaches, there is clearly potential for individualized treatment in all aspects of hepatitis treatment in the future.

Optimizing the current therapy for chronic hepatitis C virus: peginterferon and ribavirin dosing and the utility of growth factors

Achieving a sustained virologic response depends on the patient achieving three sequential independent milestones: virologic response, maintaining this response throughout treatment, and not relapsing after treatment has been completed. The ability to achieve these milestones depends on the doses of interferon/peginterferon and ribavirin used and on whether treatment with these medications is adjusted, interrupted, or prematurely discontinued in response to adverse events. This review discusses strategies to optimize peginterferon and ribavirin dosing and the impact that growth factors may have on the ability to achieve a sustained virologic response.

Performance characteristics of a real-time RT-PCR assay for quantification of hepatitis C virus RNA in patients with genotype 1 and 2 infections

BACKGROUND

Polymerase chain reaction (PCR) methods play an essential role in providing data relating to diagnosis, monitoring and treatment of hepatitis C virus (HCV) infection. The real-time reverse transcription PCR (RT-PCR) assay is an established and promising tool in terms of quantifying HCV RNA for clinical application. This study aimed to evaluate the performance characteristics of a real-time RT-PCR-based test in a clinical setting.

METHODS

Validation and reproducibility tests were performed using a standard panel. Sera from 197 chronic HCV patients were analyzed by the real-time RT-PCR assay and the results were compared with the Versant bDNA3.0 assay (bDNA3.0).

RESULTS

The real-time RT-PCR assay showed an acceptable linear response (r2=0.989-0.995) in the serial dilutions regarding genotypes 1b, 2a, 2b and 1b+2a. HCV viral loads were quantifiable in all 197 patients (100%) by the real-time RT-PCR assay and in 194 (98.5%) by the bDNA3.0. HCV RNA quantification values measured by the real-time RT-PCR and bDNA3.0 assays were positively correlated (Pearson's correlation coefficient r=0.734, p<0.001). The real-time RT-PCR assay values were on average 0.13 logs higher than the bDNA3.0 results. The correlation coefficients with genotypes 1b, 2a, 2b and mixed were 0.737, 0.711, 0.791 and 0.766, respectively (p<0.01).

CONCLUSIONS

The real-time RT-PCR assay showed comparable performance with bDNA3.0 regarding quantification of HCV viral loads with genotype 1 and 2 HCV infections.

Approach to the management of patients with chronic hepatitis C who failed to achieve sustained virologic response

The combination of PEGIFN and RBV is the most effective therapy for patients with chronic hepatitis C. Although more than half of all patients are able to achieve SVR, a significant proportion of patients, particularly those with genotype 1, fail to have undetectable HCV RNA during treatment or relapse after completing therapy with return of detectable HCV RNA. An approach in the management of these patients is to identify factors that could have led to the NR or relapse and that could be corrected before or during a second course of therapy. Because fibrosis progression occurs slowly over decades for many patients with chronic hepatitis C, avoiding alcohol or other factors that could lead to fibrosis progression may be sufficient for the vast majority of patients. Other options that could be considered in patients who have more advanced disease include retreating with one of several new antiviral agents; retreating with higher doses of IFN or PEGIFN and RBV; or using IFN, PEGIFN, or RBV monotherapy long-term as maintenance therapy. The safety and efficacy of these approaches is being evaluated in numerous clinical trials.

Comparison of the abbott 7000 and bayer 340 systems for measurement of hepatitis C virus load

This study compared two commercially available assays for the measurement of hepatitis C virus (HCV) RNA levels, the Bayer HCV RNA (version 3.0) branched DNA assay and the Abbott HCV analyte-specific reagent real-time PCR assay, to assess their quantitative relationships, ease of performance, and time to completion. The study group consisted of randomly selected patients from the NIAID human immunodeficiency virus (HIV) outpatient clinic who were infected with HIV type 1 and HCV. One hundred eighty-four samples from 66 patients coinfected with HIV and HCV receiving treatments under various protocols were analyzed for the correlation and agreement of the results. The results indicated that the two assays correlate well in the overlapping linear ranges of the assays and show good agreement. From the results obtained, we have derived a mathematical formula to compare the viral load results between the two assays, which is given as log(10) Abbott assay measure = 0.032 + 1.01 log(10) Bayer assay measure. Although it is preferable to use the same quantitation assay throughout the course of a patient's treatment, valid comparisons of the HCV RNA levels may be made between the results obtained by either of these assays in the overlapping linear range (615 to 7,700,000 IU/ml).

Real-time PCR assays for hepatitis C virus (HCV) RNA quantitation are adequate for clinical management of patients with chronic HCV infection

Because of the use of viral kinetics during polyethylene glycol (PEG)-interferon-ribavirin therapy and the development of specific new anti-hepatitis C virus (anti-HCV) drugs, assessment of the efficacy of anti-HCV drugs needs to be based not on end-point PCR assays but on real-time PCR. The aim of this study was to determine if the two available commercial real-time PCR assays, the Abbott RealTime HCV assay and the Roche Cobas TaqMan HCV assay, can become the standard for HCV RNA quantification. We investigated the prognostic relevance of HCV RNA viral loads at baseline, week 4, and week 12 to a rapid and early virological response to antiviral therapy by using the two assays. Of 59 naïve patients chronically infected by HCV (41 infected with genotype 1) who were treated with ribavirin plus PEG-interferon alfa-2b for 48 weeks, 24 patients (41%) showed a sustained virological response (SVR). With the two assays, viral loads were highly correlated, irrespective of genotype (R2=0.94 for all cases). No difference in diagnostic value was found between the Abbott and Roche assays at week 4, with respective negative predictive values (NPVs) of 84% and 78% and positive predictive values (PPVs) of 62% and 56% (not significant), and at week 12, the respective NPVs were 91% and 90% and PPVs were 44% and 46% (not significant). At week 12, 83% (20/24) and 96% (23/24) of patients with SVR tested negative for HCV RNA by the Abbott and Roche assays, respectively (the difference is not significant). In conclusion, the high sensitivities and large dynamic ranges of the Abbott and Roche assays show that a single real-time quantitative PCR assay is fully adequate for clinical and therapeutic management of HCV.

Assessment of early virological response to antiviral therapy by comparing four assays for HCV RNA quantitation using the international unit standard: implications for clinical management of patients with chronic hepatitis C virus infection

WHO International Standards for nucleic acid tests are used widely to compare the different assays used in HCV RNA quantitation. The aim of the study was to assess the impact of the international unit standard for measuring HCV RNA in the management of patients with chronic hepatitis C virus (HCV) infection. Twenty-seven naïve patients infected chronically by HCV were treated with ribavirin plus PEG-interferon-alfa-2b for 48 weeks. SVR was obtained for 16 patients (the other were non-responders). For HCV RNA quantitation, four assays were undertaken: Versant HCV RNA 3.0 (Bayer), Real time PCR (TaqMan, Roche), LCx HCV RNA (Abbott), and Cobas Amplicor-Monitor v2 (Roche). Considering a 2-log decline at Week 12 after the beginning of therapy, discordant results were found with the four HCV RNA methods in predicting SVR or non-response. At Week 4 and Week 12, significant differences were observed between Versant HCV RNA 3.0 versus PCR HCV Taqman, Versant HCV RNA 3.0 versus LCx HCV RNA, Cobas Monitor Amplicor HCV 2.0 versus LCx HCV RNA, and Cobas Monitor Amplicor HCV 2.0 versus PCR HCV Taqman (P < 0.001). The HCV RNA cutoff, given a 100% negative predictive value at Week 4 and Week 12, differed with the assays used to quantify HCV RNA, despite the use of the IU/ml units. Eighty-nine percent of serum values for HCV RNA were concordant by the IU standard. All assays, however, failed to detect HCV RNA in some cases. Despite the use of the IU standard HCV-infected patients might be monitored with only one assay.

A refined long RT-PCR technique to amplify complete viral RNA genome sequences from clinical samples: application to a novel hepatitis C virus variant of genotype 6

The goal of this study was to adapt a long RT-PCR technique to amplify large PCR fragments from the genome of hepatitis C virus (HCV) isolates using clinical samples. This was done by using a reverse transcriptase devoid of RNase H activity and a mixture of two antibody-bound thermostable polymerases to combine the high processivity of Taq and the high fidelity of Pwo with its 3'-->5' exonuclease activity. Other modifications included gentle handling during RNA extraction, the absence of tRNA and random primers, a two-step reverse transcription procedure to optimize cDNA synthesis, and increasing the annealing temperature for primers. With this approach, the HCV-1 genome (nucleotides 35-9282) was amplified consistently as two overlapping fragments of 5344 and 4675 bp from a pooled chimpanzee plasma sample containing approximately 10(6) genome copies of HCV RNA/ml. Using the conditions that we identified, 96% of the complete genomic sequence of a distinct HCV genotype 6 variant (km45) was determined from less than 300 microl of serum. This method should prove useful for molecular, epidemiological and clinical studies of hepatitis C where samples are limited but complete virus sequence is required, for example, identifying mutational hot spots of HCV under specific clinical conditions.

Comparison of qualitative (COBAS AMPLICOR HCV 2.0 versus VERSANT HCV RNA) and quantitative (COBAS AMPLICOR HCV monitor 2.0 versus VERSANT HCV RNA 3.0) assays for hepatitis C virus (HCV) RNA detection and quantification: impact on diagnosis and treatment of HCV infections

Quantitative measurements of serum hepatitis C virus (HCV) RNA are becoming increasingly important in the management of HCV-infected patients. Here we compared two quantitative assays, the COBAS AMPLICOR HCV Monitor 2.0 assay (Roche Diagnostics) and the branched DNA-based VERSANT HCV RNA 3.0 assay (Bayer Diagnostics) for HCV RNA measurement in 344 samples derived from 120 patients with chronic genotype 1 HCV infection. The overall concordance between the results of the two tests was 95%, and the HCV RNA titers within the dynamic ranges of the assays correlated very well (r2=0.86). Furthermore, both tests performed equally well in determining an early viral response at week 1 or 4 during antiviral therapy. We also compared two qualitative HCV RNA detection assays: the COBAS AMPLICOR HCV 2.0 assay versus the transcription-mediated amplification (TMA)-based VERSANT HCV RNA qualitative assay. Stored samples from sustained responders to interferon-ribavirin therapy were retested by the HCV TMA assay and were found to contain no detectable HCV RNA, demonstrating complete concordance between the results of PCR and TMA. However, HCV RNA was detected by the TMA assay in end-of-treatment (ETR) samples from 33% of patients with relapses who were HCV RNA negative according to the COBAS AMPLICOR assay. This observation suggests that a TMA assay can lead to a more correct definition of the ETR response.

Approach to the management of patients with chronic hepatitis C who failed to achieve sustained virologic response

The combination of peginterferon and ribavirin is the most effective therapy for patients with chronic hepatitis C virus (HCV) infection. Although more than half of all patients are able to achieve a sustained virologic response (SVR), a significant proportion of patients, particularly those with genotype 1, fail to have undetectable HCV RNA during treatment or relapse after completing therapy with return of detectable HCV RNA. The management of these patients creates a formidable challenge. This article outlines various strategies for patients who have failed to achieve SVR and discusses the merits of different approaches to management.

Clinical performance of the LCx® HCV RNA quantitative assay

This study was conducted to assess the performance of the Abbott laboratories LCx HCV RNA Quantitative Assay (LCx assay) in the clinical setting. Four clinical laboratories measured LCx assay precision, specificity, and linearity. In addition, a method comparison was conducted between the LCx assay and the Roche HCV Amplicor Monitor, version 2.0 (Roche Monitor 2.0) and the Bayer VERSANT HCV RNA 3.0 Assay (Bayer bDNA 3.0) quantitative assays. For precision, the observed LCx assay intra-assay standard deviation (S.D.) was 0.060-0.117 log IU/ml, the inter-assay S.D. was 0.083-0.133 log IU/ml, the inter-lot S.D. was 0.105-0.177 log IU/ml, the inter-site S.D. was 0.099-0.190 log IU/ml, and the total S.D. was 0.113-0.190 log IU/ml. The specificity of the LCx assay was 99.4% (542/545; 95% CI, 98.4-99.9%). For linearity, the mean pooled LCx assay results were linear (r=0.994) over the range of the panel (2.54-5.15 log IU/ml). A method comparison demonstrated a correlation coefficient of 0.881 between the LCx assay and Roche Monitor 2.0, 0.872 between the LCx assay and Bayer bDNA 3.0, and 0.870 between Roche Monitor 2.0 and Bayer bDNA 3.0. The mean LCx assay result was 0.04 log IU/ml (95% CI, -0.08, 0.01) lower than the mean Roche Monitor 2.0 result, but 0.57 log IU/ml (95% CI, 0.53, 0.61) higher than the mean Bayer bDNA 3.0 result. The mean Roche Monitor 2.0 result was 0.60 log IU/ml (95% CI, 0.56, 0.65) higher than the mean Bayer bDNA 3.0 result. The LCx assay quantitated genotypes 1-4 with statistical equivalency. The vast majority (98.9%, 278/281) of paired LCx assay-Roche Monitor 2.0 specimen results were within 1 log IU/ml. Similarly, 86.6% (240/277) of paired LCx assay and Bayer bDNA 3.0 specimen results were within 1 log, as were 85.6% (237/277) of paired Roche Monitor 2.0 and Bayer specimen results. These data demonstrate that the LCx assay may be used for quantitation of HCV RNA in HCV-infected individuals.

Effects of interferon treatment on liver histology and allograft rejection in patients with recurrent hepatitis C following liver transplantation

Recurrent hepatitis C after liver transplantation remains a significant cause of graft loss and retransplantation. Although treatment of recurrent hepatitis C with interferon-based regimens has become widely accepted as safe and can lead to sustained virologic clearance of hepatitis C virus (HCV) RNA, long-term histologic improvement and the risk of precipitating graft rejection remain controversial. The present study is a retrospective evaluation of the clinical and histological consequences of treating recurrent hepatitis C with interferon-based therapy in a selected group of liver transplant recipients. Twenty-three liver transplant recipients with recurrent hepatitis C and histologic evidence of progressive fibrosis completed at least 6 months of interferon, 83% of whom received pegylated-interferon alpha-2b; only 4 tolerated ribavirin. Overall, 11 patients (48%) had undetectable HCV RNA at the end of 6 months of treatment. Of these patients, 3 remained HCV RNA-negative on maintenance interferon monotherapy for 33 months, and the other 8 (35%) completed treatment and remained HCV RNA-undetectable 24 weeks after discontinuation of interferon. Overall necroinflammatory activity in liver biopsies obtained 2 years after HCV RNA became undetectable decreased significantly (7.73 +/- 2.37 vs. 5.64 +/- 2.94 units before and after treatment, respectively; P =.016). However, 5 of these 11 patients had no histologic improvement in follow-up liver histology. Liver biopsies in the 12 nonresponders demonstrated disease progression. Of the 23 patients treated with interferon, 8 (35%) had evidence of acute or chronic rejection on posttreatment liver biopsy, most of whom had no previous history of rejection (P <.01 for comparison of pretreatment and posttreatment prevalence of histologic rejection), and 2 experienced graft loss from chronic rejection, requiring retransplantation. In conclusion, interferon treatment of recurrent hepatitis C does not consistently improve histologic disease after virologic response, and it may increase the risk of allograft rejection.

Hepatitis C Infection: A Clinical Review

Nearly three million persons in the United States are viremic with hepatitis C (HCV). Despite a decreasing incidence of HCV in this country, the prevalence of HCV-related chronic liver disease is increasing. Most infections in the United States are acquired by intravenous drug use. The chronicity rate of HCV is high, reaching 85% in some populations, and the risk of progression to advanced liver disease is as high as 20% within twenty years of infection. Host factors like alcohol use accelerate the rate of progression. The enzyme immunoassay is the preferred initial test for diagnosis; the third generation assay has greater than a 99% specificity in immunocompetent patients. Barring contraindications, the standard of care for treatment of chronic HCV has become pegylated interferon and ribavirin. With this therapy, the cure rate for treatment-naïve patients is about 55%, but rates are higher in certain groups. Common side effects of therapy include neuropsychiatric symptoms, influenza-like symptoms and hematological abnormalities.

Strengths and limitations of commercial tests for hepatitis C virus RNA quantification

The sensitivity of the Roche COBAS Monitor v.2.0 test was slightly better than that of the Bayer bDNA 3.0 test, but the Monitor test underquantified specimens by 2.5- to 10.6-fold even at relatively low hepatitis C virus RNA concentrations. Dilution prior to assay minimally decreased the reproducibility of the Monitor assay, leading to the recommendation for all specimens to be diluted 1:100 prior to testing by this assay.

Controversies in the management of hepatitis C virus infection after liver transplantation

Recurrence of hepatitis C virus infection after liver transplantation is universal. A significant percentage of these patients develop progressive graft injury and cirrhosis. Those factors that modulate disease progression in liver transplant recipients with recurrent hepatitis C virus infection remain controversial and are poorly understood. Treatment of recurrent hepatitis C virus after liver transplantation with either interferon or interferon and ribavirin has yielded only limited success. Regardless of this, treatment is instituted. Peginterferon is more effective than standard interferon for treatment of chronic hepatitis C virus infection in the nontransplantation setting when used either alone or with ribavirin. The effectiveness of peginterferon, both with and without ribavirin in the posttransplantation setting, is currently being explored. In this review those factors thought to affect disease progression in patients with recurrent hepatitis C virus will be discussed, strategies that have been used to treat recurrent hepatitis C virus will be reviewed, and the impact that peginterferon may have on hepatitis C virus infection in the pretransplantation and posttransplantation setting will be explored.