Detection of hepatitis C virus RNA by a combined reverse transcription PCR assay: comparison with nested amplification and antibody testing

Circulating macrophage inflammatory protein-1β/IL-12p40 ratio predicts sofosbuvir-based treatment outcome in HCV- genotype 4 patients

This study aimed to evaluate the prognostic value of baseline macrophage inflammatory protein (MIP)-1β/IL12p40 ratio for antiviral treatment outcome in HCV genotype 4 patients.

METHODS

Sera of 450 treatment-naïve chronic HCV patients and 50 healthy individuals were collected. Liver transaminases, total bilirubin and albumin were biochemically tested, viral RNA was quantified, and circulating MIP-1β and IL-12p40 were estimated using human anti-MIP-1β and IL-12p40 antibodies in Sandwich ELISA.

RESULTS

No difference was observed in the baseline chemokines levels between responders and relapsers, but the later had a significantly higher MIP-1β/IL-12p40 ratio (P< 0.0001). Multivariate regression analysis of baseline characteristics showed that gender, age, viral load, albumin level and chemokine ratios can significantly predict treatment outcome (P= 0.0114, 0.0095, 0.042, 0.0004 and < 0.0001; respectively). Accordingly, a predictive threshold of baseline chemokine ratio was calculated and it showed an AUC of 0.6917 (P= 0.0108; 95% CI: 0.5566 to 0.8268). The calculated threshold for predicting virologic response was 8.245, with positive and negative predictive values of 92.98% and 100%; respectively. The chemokine ratios had significant correlations with liver transaminases in treated groups whether pre or post-treatment.

CONCLUSION

Baseline MIP-1β/IL-12p40 ratio represents a non-invasive prognostic biomarker that would provide shorter treatment duration and minimizes the emergence of drug-resistant variants in HCV genotype 4-patients.

Prevalence of hepatitis C among haemodialysis patients in a tertiary care hospital in south India

Background and Objectives:

Hepatitis C is the most common hepatotropic viral infection that affects patients on maintenance hemodialysis. Most of the laboratories in India depend on HCV antibody detection by ELISA. PCR based studies on detection of HCV RNA among haemodialysis patients are very scanty in India. The current study was undertaken to find the prevalence of HCV among haemodialysis patients by ELISA and PCR.

Materials and Methods:

This prospective study was conducted from January to May 2018 in a total of 100 samples. Patients more than 18 years of age, who had undergone at least 15 sessions of dialysis were enrolled in the study. All samples were screened for HCV antibody by ELISA and HCV RNA by PCR. Data regarding age and gender of the patients, history of blood transfusion, duration of hemodialysis, total bilirubin levels were collected from medical records.

Results:

Among the 100 samples, only one was positive for HCV antibody by ELISA. Eight samples were positive for HCV RNA by PCR. In this study 62.5% of the HCV positives had a previous history of blood transfusion. Duration of dialysis was more among the HCV positive group but there was no statistical significance.

Conclusion:

This is the first study from the southern state of Kerala in India showing the prevalence of HCV among hemodialysis patients by PCR. Our study showed an overall HCV prevalence of 8% by PCR. All the PCR positive samples were negative by 3rd generation ELISA which is an alarming finding and further justifies the need for PCR for detecting HCV.

Development and validation of an RT-qPCR assay for rapid detection and quantification of hepatitis C virus RNA for routine testing in Moroccan clinical specimens

A one-step reverse transcription quantitative PCR (RT-qPCR) assay in combination with rapid RNA extraction was evaluated for routine testing of hepatitis C virus (HCV) RNA. Specific primers and probes were designed for the detection of a 150 bp sequence located in the 5'untranslated region (5'UTR) of HCV RNA. The target sequence was selected as the most conserved region between the six known HCV subtype sequences following an alignment. The assay was able to quantify a dynamic linear range of 10⁸ to 10¹ plasmid copies/reaction (r²  = 0.98) containing the target sequence. Two copies of this HCV plasmid corresponds to one international unit (IU) measured using a standard obtained by serial dilutions of the World Health Organization (WHO) standard. The detection limit of the assay was about 10 IU/mL of HCV RNA (20 copies/mL) in plasma samples. The assay was comparable to Cobas AmpliPrep/Cobas TaqMan® HCV Test, v2.0 Quantitative assay (Roche Molecular Systems, Inc., Branchburg, NJ) with correlation coefficient r²  = 0.98. The present assay could be completed within 3 hours from RNA extraction to data analysis of at least 30 plasma samples. Our test provides sufficient sensitivity, specificity, and reproducibility and proved to be fast, labor-saving, and cost-effective. Indeed, our system will definitely allow low-income countries to monitor accurately this viral infection and to efficiently treat their infected patients.

Use of duplex mutation primers for real-time PCR quantification of hepatitis C virus RNA in serum

BACKGROUND

The duplex mutation primers offer many advantages over other multi-labeled probes for real-time detection of amplification products.

OBJECTIVES

To develop and validate a novel real-time PCR for quantification of HCV RNA based on the duplex mutation primers technology.

MATERIALS AND METHODS

The duplex mutation primers were selected in the highly conservative 5' non-coding region (5'NCR) of the HCV RNA. The assay was validated with the Viral Quality Control panel, which also includes Chinese HCV RNA standards.

RESULTS

The detection limit was 57 IU/mL, and a good linear correlation in the range of 102-108 IU/mL was revealed (r(2) = 0.999) with the novel method. This assay has a dynamic range of at least 8 log10 without the need for specimen dilution, good clinical intra- and inter-run precision, and excellent correlation with a commercially available assay(r(2) = 0.95).

CONCLUSIONS

The high sensitivity, wide linear range, and good reproducibility, combined with low cost, make this novel quantitative HCV real-time PCR assay particularly well suited for application to clinical and epidemiological studies.

Development of a low-cost real-time reverse transcriptase-polymerase chain reaction technique for the detection and quantification of hepatitis C viral load

BACKGROUND

It is necessary to develop a highly specific and sensitive assay to quantify the exact amount of hepatitis C virus (HCV) RNA in blood of patients with hepatitis C. For this reason, a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assay for quantification of HCV RNA in human plasma was developed.

METHODS

A pair of primers as well as hybridization probes were selected. A real-time RT-PCR was set up and optimized. To establish the sensitivity of the assay, a serial dilution of HCV standards and reference sera, including the six major HCV genotypes, was used. The performance of the assay was evaluated with 191 known HCV-RNA positive and 100 negative samples.

RESULTS

The real-time assay had a sensitivity of 50 IU/mL, with a dynamic range of detection between 10(3) and 10(6) IU/mL. The coefficients of variation of threshold cycle values in intra- and inter-day-runs were <1.77% and 3.40%, respectively. Measurement of HCV-RNA positive samples yielded reproducible data with 100% specificity.

CONCLUSIONS

The high sensitivity, simplicity, reproducibility, wide dynamic range, and low cost of this real-time HCV RNA quantification makes this method especially suitable for monitoring viral load during therapy and tailoring of treatment schedules accordingly.

Hepatic iron accumulation may be associated with insulin resistance in patients with chronic hepatitis C

BACKGROUND/AIM

Insulin resistance and hepatic iron overload are frequently demonstrated in hepatitis C virus (HCV)-related liver diseases. We investigated the relationship between insulin resistance and hepatic iron deposition in patients with chronic HCV infection.

METHODS

Insulin resistance was evaluated using the homeostasis model assessments for insulin resistance (HOMA-IR) in 56 non-diabetic non-obese patients with biopsy proven chronic hepatitis C. The relationship between insulin resistance and serum ferritin levels or the grade of hepatic iron deposition was assessed.

RESULTS

The levels of plasma immunoreactive insulin (IRI) and HOMA-IR were significantly correlated with serum ferritin levels and the grade of hepatic iron deposition (P = 0.003).Although IRI and HOMA-IR increased in parallel with the development of hepatic fibrosis, insulin resistance (HOMA-IR > 2) was observed in 11 (26.2%) of 42 patients even without severe fibrosis (F0-2). Among patients without severe fibrosis, IRI and HOMA-IR were significantly higher in patients with iron deposits than in those without iron deposits.

CONCLUSION

Hepatic iron overload may be associated with insulin resistance in patients with chronic hepatitis C, especially in patients with mild to moderate fibrosis.

Strategic approach to produce low-cost, efficient, and stable competitive internal controls for detection of RNA viruses by use of reverse transcription-PCR

Molecular diagnostics based on reverse transcription (RT)-PCR are routinely complicated by the lack of stable internal controls, leading to falsely negative results. We describe a strategy to produce a stable competitive internal control (CIC) based on a Qbeta phage derivative (recombinant Qbeta [rQbeta]) bearing primers KY78 and KY80, which are widely used in the detection of hepatitis C virus (HCV). rQbeta was RNase resistant and stable at 4 degrees C for 452 days in SM medium (0.1 M NaCl, 8 mM MgSO(4).7H(2)O, 50 mM Tris HCl [pH 7.5], 2% gelatin) and for 125 days after lyophilization and reconstitution. rQbeta performance as a CIC was evaluated. rQbeta was added to HCV-positive samples, followed by RNA extraction and a CIC-HCV RT-PCR assay. This method combines RT-PCR, liquid hybridization with nonradioactive probes, and enzyme immunoanalysis. No influence of the CIC on qualitative HCV detection was observed independently of viral load, and results had high concordance with those of commercial kits. In conclusion, we describe a versatile, low-cost alternative strategy to armored RNA technology that can be adapted for detection or real-time applications of any RNA target. Moreover, the CIC reported here is an essential reagent for HCV screening in blood banks in resource-limited settings.

Correlation of hepatic steatosis with body mass index, serum ferritin level and hepatic fibrosis in Japanese patients with chronic hepatitis C

AIMS

The present study was aimed at determining the predictors of hepatic steatosis and fibrosis in Japanese patients with chronic hepatitis C.

METHODS

The relationship between the degrees of hepatic steatosis or fibrosis and several clinical parameters was evaluated using univariate and multivariate analyses.

RESULTS

Steatosis was observed in 117 out of 184 patients (64%), including 45 patients (25%) with grade 1 (<10% of hepatocytes affected), 56 patients (30%) with grade 2 (10-30%), 12 patients (7%) with grade 3 (30-50%), and four patients (2%) with grade 4 (>50%). In the multivariate analysis, body mass index (BMI) (P = 0.0038) and serum ferritin (P < 0.0001) were selected as independent predictors of hepatic steatosis. Six of the 184 patients (3%) had stage 0 fibrosis (no fibrosis), 87 patients (47%) had stage 1, 55 patients (30%) had stage 2 and 36 patients (20%) had stage 3. In the multivariate analysis, platelet count (P = 0.0012), aspartate aminotransferase (AST) (P = 0.0219), hyaluronic acid (P < 0.0001) and the grade of steatosis (P = 0.0008) were selected as independent predictors of hepatic fibrosis.

CONCLUSION

Obesity and iron storage, as evaluated by BMI and serum ferritin level, respectively, have important roles in the pathogenesis of hepatic steatosis, which is a factor responsible for the development of hepatic fibrosis in Japanese patients with chronic hepatitis C.

Effects of dietary iron reduction versus phlebotomy in patients with chronic hepatitis C: results from a randomized, controlled trial on 40 Japanese patients

BACKGROUND AND AIM

Iron may play an important role in the pathogenesis of hepatitis C. We conducted this randomized, controlled trial comparing phlebotomy with dietary iron reduction.

METHODS

Forty patients with chronic hepatitis C showing serum ferritin levels of over 150 ng/ml were randomized to either group A (low-iron diet for six months) or group B (phlebotomy biweekly). Phlebotomy was continued until serum ferritin had reached 20 ng/ml or less.

RESULTS

At enrollment the clinical characteristics of patients in the two groups were similar. Serum ALT levels were significantly reduced in both groups, but the percent change in alanine aminotransferase (ALT) was larger in group B (median, -47.1 [range, -69.1 to -16.7] %) than in group A (-24.2 [-72.6 to 15.9] %, p<0.001). In group A subjects, no correlation was detected between percent change in ALT and clinical parameters. In group B subjects, the baseline ALT activity was significantly correlated with percent change in ALT (p<0.05), but iron-related parameters were not correlated.

CONCLUSION

The efficacy of phlebotomy is superior to that of dietary iron reduction in chronic hepatitis C. Serum levels of transaminase activities were a better indicator for phlebotomy than conventional indices of iron overload.

Reduction of virus burden-induced splenectomy in patients with liver cirrhosis related to hepatitis C virus infection

AIM: To examine the hepatitis C virus (HCV) levels and immunological markers in cirrhotic patients after splenectomy.

METHODS: HCV RNA titers as well as cellular and humoral immune markers were determined in 20 cirrhotic patients after splenectomy and in 32 cirrhotic controls with an intact spleen.

RESULTS: Serum HCV RNA titers were lower in the splenectomized patients than in the controls (186  ±  225 × 10³ copies/mL vs 541  ±  417 × 10³ copies/mL, P < 0.01). HCV RNA was judged to have been spontaneously eradicated in 4 splenectomized patients, but in none of the controls. Natural killer cell activity was higher in the splenectomized patients than in the controls (41.2  ±  19.3% vs 24.7  ±  15.3%, P < 0.01), and natural killer cell activity was negatively correlated to HCV RNA titers in the splenectomized patients except in those with serotype 2-related infection. The CD4/CD8 ratio was significantly lower in the splenectomized patients than in the controls.

CONCLUSION: The findings suggest that splenectomy may diminish virus burden in cirrhotic patients with HCV infection at least in part, through augmentation of natural killer cell activity.

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

BACKGROUND

Hepatitis C virus (HCV) is an important etiologic agent for chronic liver diseases.

METHODS

The aim of this study was to evaluate the clinical usefulness of second-generation HCV core antigen assay by comparing the results of the assay with those of the COBAS AMPLICOR HCV MONITOR version 2.0 (COBAS v2.0).

RESULTS

HCV core antigen was detectable by this assay in 142/149 (95.3%) of serotype 1 (3821+/-322 fmol/l; mean+/-SD), in 56/58 (96.6%) of serotype 2 (2589+/-449 fmol/l), and in 6/6 (100%) of serotypes 1+2 (1240+/-548 fmol/l). The HCV core antigen levels measured by this assay correlated well with the HCV RNA levels by COBAS v2.0 (r=0.848, P<0.0001). In relation to the outcome of interferon monotherapy, the pretreatment HCV core antigen levels of sustained and non-sustained virological responders were 659+/-189 and 4904+/-376 fmol/l in serotype 1, 1993+/-740 and 3145+/-519 fmol/l in serotype 2. The cutoff values with the best accuracy for HCV core Ag levels to discriminate between sustained and non-sustained virological response were 699 fmol/l for serotype 1 and 292 fmol/l for serotype 2, respectively, by receiver operating characteristic curve analysis.

CONCLUSION

This new assay was considered to be useful in evaluating the HCV levels in patients with chronic hepatitis C.

Comparison of hepatitis C virus NS5b and 5' noncoding gene sequencing methods in a multicenter study

A national evaluation study was performed in 11 specialized laboratories with the objective of assessing their capacities to genotype hepatitis C virus (HCV) and define the applicability of a given genotyping method. The panel consisted of 14 samples positive for HCV RNA of different genotypes (including 3 samples with two different artificially mixed genotypes) and 1 HCV-negative sample. Seventeen sets of data were gathered from the 11 participating laboratories. The sensitivities ranged from 64.3 to 100% and from 42.7 to 85.7% for the methods that used sequencing of the NS5b region and the 5' noncoding (5' NC) region, respectively. When the data for the artificially mixed samples were excluded, NS5b genotyping gave correct results for 80% of the samples, 1.7% of the samples were misclassified, and 18.3% of the samples had false-negative results. By 5' NC-region genotyping methods, 58.3% of the results were correct, 29.7% were incomplete, 8.3% were misclassifications, 1.2% were false positive, and 2.4% were false negative. Only two procedures based on NS5b sequencing correctly identified one of the three samples with mixtures of genotypes; the other methods identified the genotype corresponding to the strain with the highest viral load in the sample. Our results suggest that HCV 5' NC-region genotyping methods give sufficient information for clinical purposes, in which the determination of the subtype is not essential, and that NS5b genotyping methods are more reliable for subtype determination, which is required in epidemiological studies.

Simultaneous assay of DNA and RNA targets in the whole blood using novel isolation procedure and molecular colony amplification

A universal procedure that permits the whole human blood to be tested for the presence of single molecules of DNA and RNA targets is described. The procedure includes a novel protocol for the isolation of total nucleic acids from the guanidinium thiocyanate lysate of unfractionated blood in which, prior to phenol/chloroform extraction, the sample is deproteinized by precipitation with isopropanol. The procedure results in a nearly 100% yield of DNA and RNA, preserves the integrity of RNA, and removes any polymerase chain reaction (PCR) inhibitors. Following reverse transcription (RT), target molecules are counted after having been amplified as molecular colonies by carrying out PCR in a polyacrylamide gel. The entire procedure was checked by assaying viral DNA and RNA in 100-microl aliquots of the whole blood and was found to be capable of detecting 100% molecules of DNA target and 50% molecules of RNA target. Unexpectedly, nucleic acids at relatively high concentrations (1 ng/microl) were found to selectively inhibit the RT activity of Thermus thermophilus DNA polymerase without affecting its DNA-dependent polymerization activity. It follows that the popular single-enzyme RT-PCR format, in which this DNA polymerase serves for both RT and PCR, is not appropriate for assaying rare RNA targets.

Laboratory evaluation of a fully automated chemiluminescence immunoassay for rapid detection of HBsAg, antibodies to HBsAg, and antibodies to hepatitis C virus

The performance of a fully automated, random access, enhanced chemiluminescence immunoassay (Ortho/ECi) for the detection of antibody to hepatitis C virus (HCV) (anti-HCV), HBsAg, and antibody to HBsAg (anti-HBsAg), in human serum was compared to a Abbott second-generation enzyme immunoassay (EIA 2.0). The Ortho/ECi assays employ an immunometric technique with enhanced chemiluminescence for optimal assay performance. With regard to the study of clinical laboratory performance, six groups of sera prescreened with Abbott EIAs were assayed: anti-HCV-negative samples (n = 318), anti-HCV-positive samples (n = 177), anti-HBsAg-negative samples (n = 241), anti-HBsAg-positive samples (n = 239), HBsAg-positive samples (n = 158), and HBsAg-negative samples (n = 312). Sera with discrepant results in the two serological assays were resolved by confirmatory tests. Sera with indeterminate results by one or more confirmatory tests were evaluated by reviewing medical records. The overall concordance between the Ortho/ECi assay and the Abbott EIA were 97.78, 93.54, and 97.66% for anti-HCV antibodies, anti-HBsAg antibodies, and HBsAg, respectively. After resolving the discrepancies, the specificities of the new assay for anti-HCV and anti-HBsAg antibodies and HBsAg were 98.1, 92.8, and 100%, respectively. The sensitivities of the new assay for anti-HCV, anti-HBsAg, and HBsAg were 100, 98.8, and 97.4%, respectively. In conclusion, The Ortho/ECi assays for diagnosis of HCV and hepatitis B virus (HBV) infections are highly specific and sensitive assays. The rapid turnaround time, random access, full automation, and high throughput make it an effective assay system for clinical laboratory diagnosis of HCV and HBV infections.

Hepatitis C virus infection in a Brazilian population with sickle-cell anemia

Patients with sickle-cell anemia submitted to frequent blood transfusions are at risk of contamination with hepatitis C virus (HCV). Determination of HCV RNA and genotype characterization are parameters that are relevant for the treatment of the viral infection. The objective of the present study was to determine the frequency of HCV infection and the positivity for HCV RNA and to identify the HCV genotype in patients with sickle-cell anemia with a history of blood transfusion who had been treated at the Hospital of the HEMOPE Foundation. Sera from 291 patients were tested for anti-HCV antibodies by ELISA 3.0 and RIBA 3.0 Chiron and for the presence of HCV RNA by RT-PCR. HCV genotyping was performed in 19 serum samples. Forty-one of 291 patients (14.1%) were anti-HCV positive by ELISA and RIBA. Both univariate and multivariate analysis showed a greater risk of anti-HCV positivity in those who had started a transfusion regime before 1992 and received more than 10 units of blood. Thirty-four of the anti-HCV-positive patients (34/41, 82.9%) were also HCV RNA positive. Univariate analysis, used to compare HCV RNA-negative and -positive patients, did not indicate a higher risk of HCV RNA positivity for any of the variables evaluated. The genotypes identified were 1b (63%), 1a (21%) and 3a (16%). A high prevalence of HCV infection was observed in our patients with sickle-cell anemia (14.1%) compared to the population in general (3%). In the literature, the frequency of HCV infection in sickle-cell anemia ranges from 2 to 30%. The serological screening for anti-HCV at blood banks after 1992 has contributed to a better control of the dissemination of HCV infection. Because of the predominance of genotype 1, these patients belong to a group requiring special treatment, with a probable indication of new therapeutic options against HCV.

Evaluation of the clinical usefulness of COBAS AMPLICOR HCV MONITOR assay (ver2.0): Comparison with AMPLICOR HCV MONITOR assay (ver1.0) and HCV core protein level

The quantitation of serum levels of hepatitis C virus (HCV) RNA in chronic hepatitis C has been regarded as one of the most important indicators for the outcome of interferon (IFN) therapy. The AMPLICOR HCV MONITOR version 1.0 (AMPLICOR v1.0) assay is widely used for the evaluation of the HCV level. A new generation assay called the COBAS AMPLICOR HCV MONITOR version 2.0 (COBAS v2.0) assay, which is semiautomated and modified to amplify all genotypes equally, has been developed. The aim of this study was to evaluate the clinical relevance of the COBAS v2.0 assay in comparison with the AMPLICOR v1.0 assay and HCV core protein assay in patients with chronic hepatitis C before IFN therapy. HCV RNA was detectable in 230 cases (97.5%) and undetectable in 6 cases (2.5%) by the COBAS v2.0 assay. The RNA levels measured by the AMPLICOR v1.0 assay correlated significantly with those measured by the COBAS v2.0 assay, and the sensitivity of the new version 2.0 assay was better than that of version 1.0, especially in serotype 2. In relation to the outcome of IFN therapy, HCV RNA levels from virologically sustained responders by the AMPLICOR v1.0 assay were 82.3 +/- 22.9 kcopies/ml in serotype 1 and 36.9 +/- 13.4 kcopies/ml in serotype 2, and those from virologically nonsustained responders were 525.2 +/- 48.6 kcopies/ml in serotype 1 and 76.7 +/- 19.5 kcopies/ml in serotype 2. The rates of sustained response to <100 kcopies/ml were 34/63 (54.0%) in serotype 1 and 24/48 (50.0%) in serotype 2. A statistically significant virological response was seen in serotype 1 (P < 0.0001), but not in serotype 2. In contrast, the levels in virologically sustained responders by the COBAS v2.0 assay were 88.2 +/- 20.5 KIU/ml in serotype 1 and 136.8 +/- 40.1 KIU/ml in serotype 2, and those in virologically nonsustained responders were 608.8 +/- 48.4 KIU/ml in serotype 1 and 328.3 +/- 62.8 KIU/ml in serotype 2. The rates of sustained response to <100 KIU/ml were 33/60 (55.0%) in serotype 1 and 21/35 (60.0%) in serotype 2. Statistical significance in virological response was seen in both serotype 1 (P < 0.0001) and serotype 2 (P < 0.05). Although the sensitivity of the HCV core protein assay was lower than that with the COBAS v2.0 assay, the HCV core protein levels also correlated well with the results of the COBAS v2.0 assay. The HCV core protein levels of virologically sustained responders were 37.6 +/- 12.0 pg/ml in serotype 1, 81.3 +/- 37.0 pg/ml in serotype 2, and those of virologically nonsustained responders were 289.9 +/- 23.5 pg/ml in serotype 1, 191.4 +/- 32.1 pg/ml in serotype 2. This assay could predict the outcome of IFN therapy in both serotype 1 (P < 0.0001) and serotype 2 (P < 0.05). Thus, both the COBAS v2.0 assay and the HCV core protein assay showed that the viral load was an indicator of virologically sustained response in serotype 2 and in serotype 1.

A reverse-transcription competitive PCR assay based on chemiluminescence hybridization for detection and quantification of hepatitis C virus RNA

A reverse-transcription competitive PCR (RT-cPCR) combined with chemiluminescence hybridization was designed for the detection and quantitative determination of serum hepatitis C virus (HCV) RNA. The concentration of HCV RNA was calculated based on an external standard curve that was generated by coamplification of internal competitor and target sequences in serial dilutions. The detection limit of the chemiluminescence RT-cPCR was 100 copies/ml (94 IU/ml). Meanwhile, the linear range for quantitation extended from 850 copies/ml (795 IU/ml) to 4.95x10(7) copies/ml. The performance of the current assay for measuring circulating HCV levels from 26 anti-HCV-antibody positive patients was compared with that of branched-chain DNA (bDNA) and nested RT-PCR assays. Eighteen patients had HCV RNA levels that exceeded the quantitation limit by the chemiluminescence RT-cPCR, but only 11 patients were quantitation-positive by the bDNA. A significant correlation of the quantitation values was found between the chemiluminescence RT-cPCR and the bDNA (R2=0.8391). Among the eight patients with HCV RNA titers below the quantitation limit, four remained positive by the chemiluminescence cRT-PCR, demonstrating the results in agreement with those using the nested RT-PCR. Furthermore, good linearity was revealed for the HCV genotypes 1b, 2a, 2b in 3-order magnitude diluted serum samples. In conclusion, the proposed chemiluminescence RT-cPCR method can detect quantitatively HCV RNA as accurately as the bDNA method and has sensitivity as high as nested RT-PCR.

Real-time RT-PCR for quantitation of hepatitis C virus RNA

A newly developed real-time RT-polymerase chain reaction assay for quantitation of hepatitis C virus (HCV) RNA in human plasma and serum was applied. A pair of primers and a probe (molecular beacon) were designed that are specific for the recognition of a highly conservative 5'-non-coding region (5'-NCR) in HCV genome. HCV real-time RT-PCR assay had a sensitivity of 1000 RNA copies per reaction, with a dynamic range of detection between 10(3) and 10(7) RNA copies. The coefficient variation of threshold cycle (Ct) values in intra- and inter-runs were less than 1.37 and 4.66%, respectively. The real-time RT-PCR assay on the HCV sero-positive samples yielded reproducible data, with less than 2.09% of the inter-assay variation. In order to determine its potential for clinical diagnosis, real-time RT-PCR was used to examine the HCV RNA levels in plasma from sero-positive and negative subjects, showing that the assay is highly sensitive and has specificity of 100%. It was demonstrated that the real-time RT-PCR was able to amplify HCV RNA in reference sera with seven genotypes (1A, 1B, 2B, 3A, 4, 5A and 6A) that include six major HCV genotypes circulated in the world. Since HCV is a major pathogen of post-transfusion and community-transmitted non-A, non-B hepatitis, this assay has a broad application for basic and clinical investigations.

Advances in the molecular diagnosis of hepatitis C and their clinical implications

Serologic assays for diagnosis of hepatitis C infection may yield indeterminate results despite improvements in sensitivity and specificity through second- and third-generation assays. Direct detection of hepatitis C virus (HCV) RNA based on qualitative reverse transcription-polymerase chain reaction or transcription-mediated amplification allows diagnosis in the early stages of acute infection and in patients unable to mount an antibody response. Quantitative HCV RNA assays are useful for selecting appropriate antiviral therapies, but until recently they have lacked comparability between tests. More sensitive qualitative assays should be used for determining duration of treatment or recognizing a sustained virologic response to therapy. Hepatitis C virus genotyping can be performed from a limited sequence analysis of the viral genome by using various techniques. Although newer genotyping methods are relatively practicable and are satisfactory for the discrimination of the majority of genotypes, discrimination between subtypes can be challenging. Serologic typing of HCV lacks sensitivity and specificity compared with molecular-based techniques. Recent advances in serologic assays and nucleic acid detection techniques allow physicians to make accurate diagnoses, and these assays serve as important tools in treatment planning.

Advances in the molecular diagnosis of hepatitis C and their clinical implications

Serologic assays for diagnosis of hepatitis C infection may yield indeterminate results despite improvements in sensitivity and specificity through second- and third-generation assays. Direct detection of hepatitis C virus (HCV) RNA based on qualitative reverse transcription-polymerase chain reaction or transcription-mediated amplification allows diagnosis in the early stages of acute infection and in patients unable to mount an antibody response. Quantitative HCV RNA assays are useful for selecting appropriate antiviral therapies, but until recently they have lacked comparability between tests. More sensitive qualitative assays should be used for determining duration of treatment or recognizing a sustained virologic response to therapy. Hepatitis C virus genotyping can be performed from a limited sequence analysis of the viral genome by using various techniques. Although newer genotyping methods are relatively practicable and are satisfactory for the discrimination of the majority of genotypes, discrimination between subtypes can be challenging. Serologic typing of HCV lacks sensitivity and specificity compared with molecular-based techniques. Recent advances in serologic assays and nucleic acid detection techniques allow physicians to make accurate diagnoses, and these assays serve as important tools in treatment planning.

Quantitation of HCV RNA using real-time PCR and fluorimetry

Real-time PCR technology may provide an accurate and sensitive method to quantify hepatitis C virus (HCV) RNA. So far, studies have been carried out using the Taqman technology with the ABI Prism 7700 sequence detector. An alternative and simple real-time PCR assay is described with no probe requirement, based on the SYBR Green I dye and LightCycler fluorimeter. Amplicon synthesis was monitored continuously by SYBR Green I dye binding to double stranded DNA during PCR of the 5' HCV non-coding (NC) region. Specificity was verified by amplicon melting temperatures. An external standard curve was constructed with serial 10 fold dilutions of a modified synthetic HCV 5' NC RNA. A wide range linear relationship (up to 3.7x10(9) copies/ml) was observed between number of PCR cycle needed to detect a fluorescent signal and number of RNA copy. Intra- and inter-assay coefficients of variation were 0.7 to 2.1 and 3.7% respectively, indicating good reproducibility of the method. Thirty-three HCV positive sera of different genotypes were quantified by this method and gave similar but more sensitive results compared to the branched DNA (bDNA) technology.

Differences in the efficacy of ursodeoxycholic acid and bile acid metabolism between viral liver diseases and primary biliary cirrhosis

AIM AND METHODS

The effects of ursodeoxycholic acid (UDCA, 600 mg/day) on liver function test values, and serum and urinary bile acids levels in hepatitis C virus-related chronic hepatitis (CH, n = 39) and liver cirrhosis (LC, n = 25), and in primary biliary cirrhosis (PBC, n = 25) were compared.

RESULTS

The percentages of improvement in alanine transaminase (ALT) and gamma-glutamyl transpeptidase (gamma-GTP) in CH were almost the same in LC. The rates of improvement in ALT in PBC were negatively correlated with histological stages in the liver. Total serum bile acid levels in LC rose to the same extent as in CH, but the increases in PBC were significantly smaller at stages 3-4 than stages 1-2. The urinary levels of hydroxylated metabolites of UDCA only slightly increased in LC, but they increased significantly at PBC stages 3-4.

CONCLUSIONS

The efficacy of UDCA was preserved in LC, but diminished at PBC stages 3-4. The poor enrichment of UDCA in the bile acid pool and extensive biotransformation of UDCA may cause the limited efficacy of UDCA in the cirrhotic stage of PBC.

Interferon-alpha treatment of chronic hepatitis C in children with hemophilia

BACKGROUND

In children with hemophilia, hepatitis C virus (HCV) is the major cause of chronic liver disease. In this study, long-term efficacy of interferon-alpha was studied to determine the factors that predict a sustained response to interferon therapy in young children with hemophilia who have chronic hepatitis C.

METHODS

Seventeen Korean children with hemophilia and chronic hepatitis C were treated with 3.7 million units/m2 of interferon-alpha2a three times weekly for 6 months. Liver biopsy, pretreatment serum HCV RNA quantitation with competitive reverse transcription assay, and HCV genotyping with reverse hybridization assay were performed.

RESULTS

Hepatitis C virus genotypes 1a, 1b, and 2a were found in three (18%), five (29%), and six (35%) patients, respectively. Interferon-alpha was well tolerated, and the frequency of bleeding did not increase. Of the 17 patients, 7 (41%) had a sustained response for 3 years after the end of therapy. Patients with a sustained response had lower pretreatment serum HCV RNA levels. One (13%) of eight patients with genotype 1 and five (83%) of six with genotype 2 had a sustained response (P < 0.05).

CONCLUSIONS

Interferon-alpha treatment of chronic hepatitis C in children with hemophilia was safe and effective in producing sustained responses. The pretreatment serum HCV RNA level and viral genotype may be predictive factors for sustained response to interferon therapy.

Different turnover rate of hepatitis C virus clearance by different treatment regimen using interferon-beta

BACKGROUND/AIM

Since patients with high viral load and HCV subtype 1b are known to respond poorly to interferon (IFN) therapy, the viral dynamics of HCV RNA after initiation of interferon therapy were examined in the present study with respect to two different administration regimens, once vs. twice a day.

METHODS

Twenty-two patients with chronic hepatitis C confirmed by liver biopsy and with >1 Meq/ml of HCV RNA and HCV subtype 1b were randomly assigned to two different IFN administration regimens (6 million units of IFN once a day or 3 million units of IFN twice a day), and the serum HCV RNA level was serially measured.

RESULTS

Graphs of HCV RNA levels vs. treatment time showed an initial rapid fall, followed by a slower clearance phase. Fitting the data to a model for HCV decay proposed by Neumann et al. showed that the treatment efficacy was significantly higher with twice daily administration. Negativity for HCV RNA measured by Amplicor assay in the twice-a-day administration group was 18%, 73% and >89% at 1, 2 and 3 weeks, respectively, in contrast to 0%, 0%, and 18%, respectively, with once-a-day administration. However, a significant reduction of platelet count and albumin level, a marked increase in serum aspartate aminotransferase/alanine aminotransferase, and a high incidence of renal toxicity (proteinuria) were found in patients receiving IFN twice a day in comparison with those receiving it once a day.

CONCLUSION

The twice-a-day administration of IFN accelerated the clearance of HCV RNA from serum, leading to a more efficient virological response for patients with chronic hepatitis C, but with a high rate of renal toxicity.

Performance of the COBAS AMPLICOR HCV MONITOR test, version 2.0, an automated reverse transcription-PCR quantitative system for hepatitis C virus load determination

A clinical evaluation of an automated quantitative PCR assay, the COBAS AMPLICOR HCV MONITOR test, version 2.0 (v2.0), was carried out to assess the performance of this test in comparison with that of the previous, manual version, the AMPLICOR HCV MONITOR test, and with that of nested PCR. Serial dilutions of serum samples infected with genotype 1b, 2a, or 3, as well as synthetic RNA transcripts and serum samples derived from 87 patients with chronic hepatitis C and infected with genotype 1a, 1b, 2a, 2b, 3a, 3b, 4, or 5, were analyzed to determine the ability of the system to efficiently quantify various hepatitis C virus (HCV) genotypes. These experiments showed that the COBAS AMPLICOR HCV MONITOR test, v2.0, has mean intra-assay, interassay, and interoperator coefficients of variation that range from 22 to 34.5% and a 3-logarithm dynamic range, which spans from 10(3) to 10(6) copies/ml. Compared to the previous, manual version of the test, the COBAS AMPLICOR HCV MONITOR test, v2.0, showed an improved efficacy for all genotypes, especially genotypes 2, 3, and 4, whose estimated concentrations were on average 1 logarithm higher. When used to monitor patients under treatment, however, both versions showed the same patterns of viremia, indicating that the COBAS AMPLICOR HCV MONITOR test, v2.0, and the AMPLICOR HCV MONITOR test were equally effective at detecting relative viremia changes in serial samples. As expected, the automated test was less sensitive than nested PCR; among specimens from a cohort of patients treated with interferon, nested PCR identified three more viremic specimens, which probably contained very low concentrations of HCV RNA.

Simultaneous detection of multiplex-amplified human immunodeficiency virus type 1 RNA, hepatitis C virus RNA, and hepatitis B virus DNA using a flow cytometer microsphere-based hybridization assay

The feasibility of performing a multiplex assay for the detection of human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) RNAs and hepatitis B virus (HBV) DNA is demonstrated. This assay is based (i) on the coamplification of a 142-bp fragment from the gag region of the HIV-1 genome and a 142-bp HIV-1 quantitation standard fragment, a 244-bp fragment from the 5' noncoding region of the HCV genome, and a 104-bp fragment from the pre-C and C gene regions of the HBV genome, using three sets of specific primers; (ii) on the capacity of these four biotinylated PCR products to hybridize to their specific oligonucleotide probe-coated microspheres; and (iii) on the ability of the flow cytometer to discriminate between distinct fluorescent-microsphere categories. Absence of cross-hybridization between the unrelated oligonucleotide probes and PCR products generated by the multiplex reverse transcription-PCR (RT-PCR) and the highly sensitive detection method allowed us to assess unambiguously the HIV-1 viral load and the infectious status of 35 serologically well-established clinical samples and 20 seronegative blood donor plasma samples tested. The results indicate that multiplex RT-PCR and flow cytometer microsphere-based hybridization assays, when combined, provide a rapid, sensitive, and specific method for the quantitation and detection of the major viral agents of infectious diseases in a single plasma sample.

Sustained viral response is rarely achieved in patients with high viral load of HCV RNA by excessive interferon therapy

Adequate dosing of interferon (IFN) and its cost-effectiveness for sustained virological response were evaluated in relation to viral load and subtype. Prospective analysis of IFN therapy on 326 patients with chronic hepatitis C free from cirrhosis was performed using 9 or 6 million unit (MU) of IFN for six months daily and/or three times a week. Sustained virological response was achieved in 50-94% of patients with < or =2 x 10(4) copies/ml (competitive RT-PCR) or <100 x 10(3) copies/ml (Amplicor monitor) of HCV RNA by 468-1206 MU of IFN, but response was only 0-25% of the patients with > or =2 x 10(5.5) copies/ml (competitive RT-PCR) or >200 x 10(3) copies/ml (Amplicor monitor), even with 468-1206 MU of IFN. A high sustained rate was demonstrated in patients with 100-200 x 10(3) copies/ml of HCV RNA by 901-1206 MU of IFN, in comparison to that with < or =900 MU of IFN. Multivariate analysis showed that IFN dose had a significant value for the efficacy of IFN therapy in patients presenting 100-200 x 10(3) copies/ml of HCV RNA. Cost efficacy analysis indicated that it cost approximately $10,000, $26,000, and $50,000-227,000 for one person-viral eradication in the patients with <100, 100-200, and >200 x 10(3) copies/ml, respectively. High-dose IFN is only cost effective in patients with intermediate viral loads, and IFN therapy could be recommended in patients with <200 x 10(3) copies/ml of HCV RNA.

Nucleotide and amino acid complexity of hepatitis C virus quasispecies in serum and liver

The quasispecies nature of the hepatitis C virus (HCV) is thought to play a central role in maintaining and modulating viral replication. Several studies have tried to unravel, through the parameters that characterize HCV circulating quasispecies, prognostic markers of the disease. In a previous work we demonstrated that the parameters of circulating viral quasispecies do not always reflect those of the intrahepatic virus. Here, we have analyzed paired serum and liver quasispecies from 39 genotype 1b-infected patients with different degrees of liver damage, ranging from minimal changes to cirrhosis. Viral level was quantified by real-time reverse transcription-PCR, and viral heterogeneity was characterized through the cloning and sequencing of 540 HCV variants of a genomic fragment encompassing the E2-NS2 junction. Although in 95% of patients, serum and liver consensus HCV amino acid sequences were identical, quasispecies complexity varied considerably between the viruses isolated from each compartment. Patients with HCV quasispecies in serum more complex (26%) than, less complex (28%) than, or similarly complex (41%) to those in liver were found. Among the last, a significant correlation between fibrosis and all the parameters that measure the viral amino acid complexity was found. Correlation between fibrosis and serum viral load was found as well (R = 0.7). With regard to the origin of the differences in quasispecies complexity between serum and liver populations, sequence analysis argued against extrahepatic replication as a quantitatively important contributing factor and supported the idea of a differential effect or different selective forces on the virus depending on whether it is circulating in serum or replicating in the liver.

Spontaneous negativation of serum hepatitis C virus RNA is a rare event in type C chronic liver diseases: analysis of HCV RNA in 320 patients who were followed for more than 3 years

BACKGROUND/AIMS

The natural course of hepatitis C virus (HCV) replication in type C liver diseases has not yet been elucidated. The aim of the study was to investigate the spontaneous outcome of the viremia by examining the changes in HCV RNA in patients with chronic type C liver diseases.

METHODS

Among patients who visited our liver clinic between June 1981 and December 1993, 320 patients with chronic type C liver diseases were followed for at least 3 years and had no history of interferon treatment. HCV RNA was examined by a highly specific reverse transcription-polymerase chain reaction method in paired serum samples obtained from these patients at the beginning and end of follow-up.

RESULTS

Among the 320 cases, HCV RNA was seropositive in 310 (97%) cases at the beginning of follow-up. Of these 310, HCV RNA remained seropositive in 304 (98%) and became seronegative in six (2%) cases by the end of follow-up. All of these six patients had liver cancer. HCV RNA became seronegative after the patients entered the state of liver failure because of the development of tumors or portal thrombosis. The remaining 10 cases who were seronegative for HCV RNA at the beginning were seropositive at the end of follow-up. Among the 320 cases, serum alanine aminotransferase normalized and remained normal for more than 12 months until the end of follow-up in 11 cases (0.6%/year/case), but none became negative for HCV RNA.

CONCLUSIONS

Thus, during the natural course of chronic HCV infection, spontaneous negativation of serum HCV RNA seems extremely rare, at least in patients with chronic active hepatitis or cirrhosis of the liver, and may occur primarily at the terminal stage when tumors cause liver failure.

High rate of chronicity in HCV infection determined by antibody confirmatory assay and PCR in 4110 patients during long-term follow-up

BACKGROUND

It is still unclear how many patients with hepatitis C virus (HCV) antibodies have viremia and hence are infectious.

OBJECTIVES

To determine the chronicity of HCV infection by correlation of HCV antibodies with presence of viremia in long-term follow-up.

STUDY DESIGN

In a longitudinal study sera of 4110 patients were analyzed with second generation HCV-enzyme immunoassay (EIA) and polymerase chain reaction (PCR). Only those patients were included in this study in whom sequential serum samples over a period of 2 years were available. To avoid preanalytical and analytical failures, we used a transport solution to prevent RNA degradation and a four-antigen recombinant immunoblot assay, established in our laboratory, for confirmation of antibody reactivity.

RESULTS

Of 2815 patients with confirmed HCV antibodies 2784 (98.9%) were also positive in HCV-PCR assay. False reactive EIA results were detected in 177 (13.7%) individuals as shown by confirmatory assay and PCR. Only one patient (0.04%) spontaneously lost detectable HCV viremia and subsequently HCV-specific antibodies.

CONCLUSIONS

Our study clearly demonstrates that presence of confirmed HCV-specific antibodies correlates significantly (98.9%; P < 0.001) with HCV viremia, and that spontaneous loss of viremia is a very rare event in HCV infection. We also found that elimination of HCV infection is not sufficiently predicted by the loss of detectable viremia in PCR, but can be concluded from the disappearance of virus-specific antibodies.

Hepatitis C virus RNA profiles in chronically infected individuals: do they relate to disease activity?

Fluctuations of hepatitis C virus (HCV)-RNA serum levels were monitored in a multicenter study in 76 chronic HCV carriers who had been followed longitudinally without receiving antiviral therapy to assess their relation with the course of liver disease activity. Forty-four patients had normal transaminases over more than 2 years, while 32 additional patients had fluctuating levels. Viral load was measured in serial serum samples prospectively collected for 10 to 12 months in 54 patients and in sera stored yearly up to 8 years in an additional 22 patients. In patients tested monthly, a lesser extent of fluctuations was detected in cases with constantly normal transaminases as compared with those with fluctuating transaminases. In the former group, the mean difference between maximum and minimum values observed in each individual patient was 0.7 Log, while in the latter group, it was 1.3 Log (P =.0004). Most of these patients experienced, on average, three peaks of viremia over 1 year. The range of variation observed upon yearly testing was between 0.2 and 2.2 Log and did not reach statistical significance between the two groups. In conclusion, a careful viral replication profile can be achieved only by monthly testing, because longer time intervals could miss viremia fluctuations. HCV-RNA levels are more stable in asymptomatic HCV carriers than in patients with biochemical activity of liver disease.

High-throughput real-time reverse transcription-PCR quantitation of hepatitis C virus RNA

We describe a rapid and reproducible method for assessment of the hepatitis C virus (HCV) load in serum samples. The method combines Taqman technology (Roche) and the ABI Prism 7700 (Perkin Elmer) real-time sequence detection system. We have optimized a single-tube reverse transcription-PCR (RT-PCR) that contains a dual-labeled fluorogenic probe to quantify the 5' noncoding region (5' NCR) of HCV. The probe contains a fluorescent reporter at the 5' end and a fluorescent quencher at the 3' end. The use of such a probe combined with the 5'-3' nuclease activity of Taq polymerase allows direct quantitation of the PCR product by the detection of a fluorescent reporter released in the course of the exponential phase of the PCR. For accurate quantitation of the number of copies of HCV in samples containing unknown quantities, we have used serial dilutions of a synthetic 5' NCR RNA standard of HCV that was previously quantified with an isotopic tracer. The method has a 5-log dynamic range (10(3) to 10(7)). The coefficient of regression of the standard curve was, on average, 0.98. The intra-assay and the interassay coefficients of variation of the threshold cycle were 1% and 6.2%, respectively. Seventy-nine RNA samples from the sera of infected patients were quantified by this method. Comparison of the results with those obtained by other quantitation methods (the Quantiplex 2.0 branched-DNA assay and the Superquant assay from the National Genetics Institute) revealed a significant correlation with all of the results. The mean values were also statistically comparable. In conclusion, the high sensitivity, simplicity, and reproducibility of the real-time HCV RNA quantitation which allows the screening of large numbers of samples, combined with its wide dynamic range, make this method especially suitable for monitoring of the viral load during therapy and tailoring of treatment schedules.

How soon can a virological sustained response be determined after withdrawal of interferon therapy in chronic hepatitis C? Tokyo-Chiba Hepatitis Research Group

Hepatitis C virus (HCV)-RNA status and alanine aminotransferase (ALT) levels determined shortly after interferon (IFN) therapy in patients with chronic hepatitis C do not predict long-term response. To determine the virological sustained response after the completion of IFN therapy, HCV-RNA was measured at the end of treatment and at 3-4 months and 12 months after the completion of therapy in 537 patients with chronic hepatitis C. In 347 patients, HCV-RNA was not detected by polymerase chain reaction (PCR) at the completion of therapy and 175 of these patients (50%) were still PCR negative 12 months later. In contrast, of the 180 patients who were HCV-RNA negative at 3-4 months after completion of therapy, 99% remained negative at 12 months. Normal ALT levels were found in 80, 93 and 95% of patients who were negative for HCV-RNA either at the end of treatment or at 3-4 months and 12 months after the completion of therapy, respectively. Of patients who were HCV-RNA positive, 30, 15 and 20% were found to have normal ALT levels at the same respective time points. To determine a sustained virological response shortly after the completion of therapy, serum HCV-RNA was serially examined in 66 patients negative for HCV-RNA at the end of therapy. Of 31 patients who relapsed, HCV-RNA reappeared in 33, 80, 97 and 100% of patients by 1, 2, 4 and 8 weeks after the completion of therapy. In conclusion, a sustained virological response could be determined with 97 and 99% certainty at 4 weeks and at 3-4 months after the completion of therapy, respectively.

Multicenter evaluation of the COBAS AMPLICOR HCV assay, an integrated PCR system for rapid detection of hepatitis C virus RNA in the diagnostic laboratory

The benefits shown by the recent introduction of PCR for the in vitro diagnosis of hepatitis C virus (HCV) infection has prompted the development of standardized, ready-to-use assays that can be implemented in routine clinical laboratories. We have evaluated the clinical performance of COBAS AMPLICOR HCV (COBAS), the first instrument system that allows the automation of HCV RNA amplification and detection, to determine its performance in the routine laboratory setting. More than 2,000 specimens collected at five centers were analyzed in parallel by the COBAS and the manual AMPLICOR HCV (AMPLICOR) tests, and the results were compared with the results for biochemical and serological markers of HCV. In this study the two PCR systems showed the same accuracy, with a concordance rate of 99.8%. As expected, the correlation between serology and PCR was not absolute because the presence of anti-HCV antibodies may be associated with a latent or past infection. On the other hand, if the presence of confirmed anti-HCV antibodies and elevated alanine aminotransferase levels are taken as the "gold standard," indicating an active, ongoing infection, the COBAS and AMPLICOR tests show high and comparable sensitivities (100%) and specificities (98%), with positive and negative predictive values of 100 and 97%, respectively. During the study no false-positive reactions were detected. The use of an internal control allowed the identification of inhibitory substances that prevented amplification for 0.3 and 0.4% of samples tested by the COBAS and AMPLICOR tests, respectively. Compared to the manual system, the COBAS system allowed a significant reduction of hands-on time and could improve the overall laboratory work flow. In conclusion, these results support the use of the COBAS and AMPLICOR tests for the molecular diagnosis of active HCV infections.

Virology of hepatitis C virus

Advances in molecular biology techniques have allowed the cloning of HCV and the characterization of this virus. This article provides a short summary of our current knowledge on the genomic organization of HCV, the implications of its genetic heterogeneous nature, and the probable replication strategy of this virus.

Use and interpretation of HCV diagnostic tests in the clinical setting

The rapidly emerging and sometimes complicated field of HCV diagnostics can be simplified by classification of tests into two general categories: serologic tests which screen for anti-HCV antibodies, and molecular tests which are used to assess HCV viremia and characterize viral infection at the genetic level. Antibody tests include the highly sensitive screening enzyme immunoassays (current versions: EIA-2 and EIA-3), and supplemental tests such as the recombinant immunoblot assay (RIBA-2). Molecular assays such as HCV RNA polymerase chain reaction (PCR) may play an important role in confirming HCV infection in several clinical situations, such as immunosuppressed patients with chronic hepatitis C, patients with acute hepatitis who might be in the diagnostic "window" period prior to seroconversion, and seropositive patients with normal ALT values. Quantitative HCV-RNA tests, such as quantitative PCR (Q-PCR) and branched DNA (bDNA), provide valuable tools for assessing the level of HCV viremia prior to and during therapy. Genotype tests allow classification of HCV infection in one of six distinct HCV genotypes, although the clinical relevance of HCV genotype tests has not been established.

Clinical application of hepatitis C virus genotyping and quantitation

Genotyping and quantitation of hepatitis C virus have provided great insights into the pathogenesis of chronic hepatitis C. The assays that are currently available for characterizing HCV remain powerful research tools that will be invaluable in future studies of the next generation of antiviral agents for the treatment of hepatitis C in much the same way that they have provided information about the effectiveness of interferon. Retrospective studies have demonstrated that HCV genotype and viral burden may play some role in disease progression and response to therapy. However, their utility in daily clinical practice in making decisions about treatment regimens or monitoring therapy in an individual patient remains difficult to define. As newer, more effective treatment strategies evolve (longer duration of treatment, combination therapy), previously identified predictors of disease severity or response to treatment may no longer be applicable.

Quantitative assays for hepatitis C virus in serum as predictors of the long-term response to interferon

BACKGROUND/AIMS

Interferon therapy has a beneficial effect in patients with chronic hepatitis C who have a low viral load. The aim of this study was to compare the core protein level with HCV RNA levels and to analyze whether virus quantitation predicts the efficacy of interferon therapy.

METHODS

HCV core protein level assessed by the recently developed assay was compared with HCV RNA levels measured by three different methods (Amplicor-HCV monitor, competitive RT(CRT)-PCR, and bDNA probe assay) in 352 patients with chronic hepatitis C in relation to viral serotype.

RESULTS

From 91% (320/352) to 93% (299/322) of patients with viremia were detected by Amplicor-monitor and CRT-PCR, in contrast to 60% (187/312) and 74% (191/258) by bDNA and HCV core protein assay, respectively. The HCV core protein level was positively correlated with HCV RNA levels measured by the three assays (r = 0.680 to 0.731). Serum HCV RNA and core protein levels were significantly lower in patients with serotype 2 than in those with serotype 1. Viral eradication after interferon therapy was observed in 60-70% of the patients with < 1 x 10(4) copies/ml of HCV RNA by Amplicor-monitor assay, < 2 x 10(5) copies/ml by CRT-PCR, < 0.5 Meq/ml by bDNA assay, and < 20 pg/ml of core protein by HCV core protein assay. Viral eradication was uncommon (< 11%) among the patients with higher viral loads. Bivariate analysis revealed that the outcome of interferon therapy was more closely associated with both HCV core protein and RNA levels than the HCV serotype.

CONCLUSIONS

Quantitation of HCV core protein and HCV RNA in useful for prediction of the interferon response.

Development of a quantitative PCR assay for monitoring HCV viraemia levels in patients with chronic hepatitis C

The need to improve the efficacy of anti-viral agents directed against the hepatitis C virus (HCV) has prompted the development of quantitative tests to monitor viraemia levels in relation to therapy. In this respect, we have produced a non-competitive, quantitative PCR assay (Amplicor HCV Monitor) which is based on the single, combined, reverse transcription and amplification of the 5' non-coding region of HCV RNA as well as of an internal standard which serves to assess the overall efficiency of the system. The dynamic range of the assay and its precision allows for an accurate quantification between 1000 and 1,000,000 copies of the viral genome per ml. The results of the first clinical evaluation of the test indicated that determination of viraemia may have predictive value when assessed prior to treatment, as patients with less than 50,000 HCV RNA copies per ml tend to show a long-term response to interferon-alpha (IFN-alpha) treatment. Moreover, a decrease of more than 1.5-2 logarithms occurring at 1 month post-initiation of therapy predicts response in a more timely and accurate fashion than ALT measurement. This may help in a better selection of patients to treat, therapy approaches and schedules and in the optimization of the cost-benefit balance.

Single-step PCR in molecular diagnosis of hepatitis C virus infection

The diagnostic utility of two PCR systems and three PCR detection methods for hepatitis C virus (HCV) RNA was evaluated in serum samples. A nested PCR was considered the reference assay and was compared with two single-step PCR methods: the first is based on the detection of PCR products by liquid hybridization with a 32P-end-labeled probe, and the second is the Roche Amplicor colorimetric assay using microwell plate hybridization with a specific nucleic acid probe. Using the Pelicheck HCV RNA Eurohep genotype 1 proficiency panel, our laboratory achieved medium-high levels of performance with all three methods. The highest sensitivity was, however, observed with the isotopic single-step PCR (ss-PCR) method. The analytical sensitivity of ss-PCR with isotopic detection and ss-PCR with colorimetric detection was identical to that of nested PCR, with a 100% result concordance. Comparison of ss-PCR with enzyme-linked immunosorbent and RIBA assays in the analysis of clinical samples showed a high concordance. ss-PCR methods appear more suitable for diagnostic application. Nevertheless, HCV RNA PCR cannot be considered a screening assay; it should be requested in the presence of reactive serology or specific clinical symptomatology with altered liver parameters, and it is a potential tool for the follow-up of patients with HCV infection.

Hepatitis C virus detection by single-round PCR specific for the terminal 3' noncoding region

A single-round PCR method with primers specific for the 3' noncoding region (NCR) of hepatitis C virus (HCV) has been developed. Using a double RNAzol-B extraction, a high-temperature reverse-transcription step with SuperScript II reverse transcriptase, and a 40-cycle two-temperature PCR with a TaqStart antibody hot-start procedure, we were able to detect a 92-nucleotide fragment of the recently discovered 98-nucleotide highly conserved sequence at the 3' terminus of the HCV genome. Direct sequencing of the PCR products confirmed the specificity of the PCR and demonstrated conservation in this region. Only one nucleotide change in 14 specimens was found. End point dilution titration of sera with known viral RNA titers showed the sensitivity of the single-round 3' NCR PCR to be comparable to those of the established nested 5' NCR assays (fewer than 25 HCV genome equivalents). To evaluate specificity and sensitivity, a panel of 116 serum samples characterized by nested 5'-end PCR, genotyping, and quantitative assays was tested. A high degree of concordance (96%) between the 3' NCR and 5' NCR PCR results was found. The sequence conservation at the 3' end of the HCV genome among common genotypes and the savings in time, labor, and reagents from a single-round PCR make this assay a useful addition to the detection systems available to identify and monitor HCV infection.

Detection of hepatitis C virus by PCR in second-generation enzyme immunoassay-seropositive blood donors by using matched pairs of fresh frozen plasma and pilot tube sera

Between April 1993 and March 1995, 429 of 334,454 (0.13%) blood donations at the Toronto Centre of the Canadian Red Cross were reactive for hepatitis C virus (HCV) by second-generation enzyme immunoassay (EIA-2). Of the 429 EIA-2-positive donations, 189 (44%), 138 (32%), and 102 (24%) were positive, indeterminate, and negative by Second-Generation Recombinant Immunoblot Assay (RIBA-2). To assess HCV viremia and minimize the risk that specimen handling affected PCR-based detection, the qualitative AMPLICOR HCV test was performed on both pilot tube sera (PTS) and the corresponding fresh frozen plasma (FFP) from 294 EIA-2-reactive donations. AMPLICOR PCR results for PTS and FFP were 100% concordant and were confirmed by nested HCV PCR for 27 of 294 donations. The AMPLICOR HCV test was positive for 127 of 140 (91%) of RIBA-2-positive donations (81, 91, and 96% of donations with two, three, and four reactive bands, respectively), 5 of 88 (5.7%) indeterminate donations, and 0 of 66 (0%) RIBA-2-negative donations. The Third-Generation Recombinant Immunoblot Assay (RIBA-3) was performed on RIBA-2-negative, -indeterminate, and -positive, PCR-negative donations. RIBA-3 demonstrated enhanced specificity and resolved 18 of 88 (20%) of RIBA-2-indeterminate samples as HCV antibody positive. The study demonstrates that PTS are as suitable as FFP for PCR-based detection of HCV and can be used to determine if EIA-2-reactive blood donors are viremic at the time of donation.

Distribution of HCV genotypes among blood donors, patients with chronic liver disease, hepatocellular carcinoma, and patients on maintenance hemodialysis in Korea

Hepatitis C virus (HCV) is a single-stranded RNA virus related to the Flaviviridae family, and striking nucleotide sequence diversity has been reported among HCV isolates from different geographic areas. To study the distribution HCV genotypes among disease group in Korea, we subtyped HCV using the method of Okamoto et al. [(1992a): Journal of General Virology 73:673-679] and the reverse hybridization method (INNO-LiPA) on 138 patients who were HCV polymerase chain reaction (PCR)-positive: 30 blood donors, 30 with hepatocellular carcinoma (HCC), 33 with chronic hepatitis, 15 with liver cirrhosis, and 30 patients on maintenance hemodialysis in Korea. In 30 blood donors, HCV genotype 1b was most dominant (80%), followed by genotype 2a (13.3%), and 2b (6.7%). In 30 HCC cases, HCV genotype 1b was less frequent (60%), compared to blood donors, followed by genotype 2a (33.3%), and unclassified (6.7%). In 33 chronic hepatitis cases, HCV genotype 1b was also dominant (63.6%), followed by genotype 2a (30.3%), and 1a (6.1%). In 15 patients with liver cirrhosis, HCV genotype 1b was also dominant (60%), followed by genotype 2a (33.3%), and 1a (6.7%). In 30 patients on maintenance hemodialysis, HCV genotype 1b was dominant (86.7%), followed by genotype 2a (13.3%). In conclusion, among 138 HCV PCR-positive patients, type 1b was the prevailing type (71%), followed by type 2a (23.9%), type 1a (2.1%), type 2b (1.5%), and unclassified (1.5%) in Korea. The prevalence of type 1b in blood donors (80%) was higher than in patients with liver disease (61.5%) and the prevalence of type 1b was the lowest in patients with HCC (60%).