Changes in HCV Viremia following LDL Apheresis in a HCV Positive Patient with Familial Hypercholesterolemia

It has been suggested that hepatitis C virus (HCV) can be associated with beta-lipoprotein in human serum. According to this, the LDL receptor could promote endocytosis of such a virus. In the present study, we evaluated the changes in HCV viremia in a HCV positive patient with familial hypercholesterolemia, undergoing both selective (DALI System, Fresenius) and non-selective (plasma exchange) LDL apheresis. HCV-RNA levels did not decrease following selective LDL apheresis, on the contrary showed a random, odd variation pattern (from –35% to +72%). Conversely, plasma exchange steadily induced a drop in HCV viremia (–35/43%), to a lower extent than that of a totally intravascular plasmaprotein, i.e., alpha 2-macroglobulin (–53/54%). These data indicate that beta-lipoprotein may not function as a plasma carrier of HCV, at least in the present case. Moreover, a continuous, quantitatively unforeseeable circulation of HCV virions from the intravascular plasma compartment to other extravascular and intracellular sites, seems to occurr during an apheresis session.

Development and evaluation of a quantitative competitive reverse transcription polymerase chain reaction (RT-PCR) for hepatitis C virus RNA in serum using transcribed thio-RNA as internal control

A method for quantitation of hepatitis C virus (HCV) RNA was developed based on competitive reverse transcription polymerase chain reaction (RT-PCR) using in vitro transcribed mutated thio-RNA as a competitor template. The thio-RNA is more resistant to RNAse and is stable over a year. This assay was compared with the commercially available Roche Amplicor HCV Monitor assay V 2.0 and real time PCR using SYBR green 1 dye method. A total of 18 pre-therapy serum samples from chronic hepatitis C cases were tested in parallel by the three assays. All samples could be quantitated using the in-house competitive RT-PCR and real time PCR and there was a significant correlation in the virus titer (P<0.05). However, 8 (44%) samples could not be quantified by Amplicor HCV Monitor assay, which has a lower detection range (10(2) to 10(5.5) copies/ml). The in-house method of competitive RT-PCR showed a detection range of 10(3) to 10(10) copies/ml. In the patients the mean viral titer was found to be (9.66+/-9.3)x10(6) copies/ml. Ten (55%) of the samples, assessed by the Amplicor HCV Monitor assay showed a mean viral titre of (1.13+/-0.75)x10(6) copies/ml, which was lower than the other two tests. The competitive PCR method and real time PCR could amplify all prevalent genotypes. This in-house quantitative competitive RT-PCR method is simple, cheap, reproducible and useful for estimation of HCV RNA load.

Hepatitis C virus genetic variability: pathogenic and clinical implications

HCV is variable because of the properties of the viral RdRp, high levels of replication, and large population sizes. The Darwinian evolution of HCV has been characterized by the emergence of the HCV genotypes, including six main types and a large number of subtypes. The study of HCV genotype epidemiology provides useful information on the worldwide HCV epidemics. The HCV genotype is an important predictor of the response to IFN-alpha-based antiviral therapy, and genotype determination is currently used to tailor treatment indications. In addition, HCV circulates and behaves in infected individuals as mixtures of closely related but distinct viral populations referred to as quasispecies. This particular nature of the virus influences its transmission, the pathogenesis of liver disease and extra-hepatic manifestations, and the outcome during and after antiviral therapy or after transplantation for HCV-related end-stage liver disease. Further studies are needed to understand better the implications of HCV quasispecies diversity in the pathophysiology of HCV infection.

Immunohistochemical detection of hcv in cirrhosis, dysplastic nodules, and hepatocellular carcinomas with parallel-tissue quantitative RT-PCR

Hepatitis C virus is a major risk factor for hepatocarcinogenesis in humans. In situ detection of the virus in early sequential lesions of hepatocarcinogenesis could provide information about the role of the virus in the transformation and promotion process. Parallel in situ detection of HCV proteins and RNA in human tissues were performed in 55 posthepatitis C cirrhosis, 17 dysplastic nodules (DN), and 25 hepatocellular carcinomas (HCC), using immunohistochemistry and tissue quantitative RT-PCR. A consistent cytoplasmic hepatocellular staining was obtained in 73% of cirrhosis cases (with or without HCC) and in 55% DN cases. A few tumoral hepatocytes were unambiguously stained in 28% HCC. The percentage of positive cells and the intensity of immunostaining significantly decreased from cirrhosis to HCC through DN, whereas there was no difference in the prevalence of positivity or the number of viral copies between cirrhosis and HCC using tissue-quantitative RT-PCR. Finally, RT-PCR levels were found parallel with the immunostaining in cirrhosis but not in HCC. These results suggest that HCV protein synthesis may persist but be down-regulated during sequential hepatocarcinogenesis. A putative role of HCV proteins on cell proliferation and differentiation during the early steps of carcinogenesis cannot therefore be excluded.

Hepatitis C virus carriers with persistently normal aminotransferase levels: healthy people or true patients?

Since the discovery of hepatitis C virus, the availability of serological hepatitis C virus screening has led to the identification of many subjects with normal aminotransferase levels who are chronically infected by the hepatitis C virus. To date, the epidemiology and natural history of subjects with normal aminotransferase levels are far from being clarified. Further, whether subjects with persistently normal aminotransferase levels should routinely undergo liver biopsy is still extremely controversial, and benefit from interferon treatment in this group of patients is yet to be proven. On account of the consistent normality of aminotransferases, it is not easy to calculate the rate of persons with normal aminotransferase levels among chronic hepatitis C virus carriers, nor their prevalence in the general population. It has been estimated that up to 25% of patients with chronic hepatitis C virus infection have persistently normal aminotransferase levels (10% to 40%, according to different studies). Most studies showed a clear prevalence of females, ranging from 58% to 90%. Liver biopsy shows some degree of chronic liver disease in up to 80% of these subjects, although in the majority, histological damage is mild and probably does not progress to more severe liver disease, moreover, the progression to fibrosis is slower than in patients with elevated aminotransferase levels. Virological features of these subjects (hepatitis C virus genotype distribution, viral load, quasispecies diversity) do not differ with respect to patients with elevated aminotransferase levels although a higher frequency of non 1 hepatitis C virus types has been reported. To date, no biochemical or virological tools to assess the presence and severity of liver damage exist. Antiviral treatment with interferon may induce a long-term response in only a small proportion of hepatitis C virus carriers with persistently normal aminotransferase levels, and many patients develop aminotransferase-flare-up during or shortly after treatment. Thus, interferon or combination antiviral treatment of hepatitis C virus carriers with normal aminotransferase values should be avoided in clinical practice.

HCV RNA levels in hepatocellular carcinomas and adjacent non-tumorous livers

To determine the antiviral effects of drugs targeted to hepatitis C virus (HCV) in chronic hepatitis patients, an accurate quantitative method with high sensitivity is needed. Reverse transcription nested polymerase chain reaction (RT-PCR) is the most sensitive method for the detection of HCV sequences in clinical specimens. However, this method is not quantitative. For this purpose, a quantitative competitive assay was developed that combines RT and PCR followed by image analysis to quantify HCV RNA. This assay targets the highly conserved 5' non-coding region of HCV and is based on the co-amplification of wild type HCV RNA with known amounts of mutant synthetic RNA. The mutant internal control used in these experiments differs from the wild type RNA by two nucleotide substitutions, which introduces an internal restriction enzyme site. In this report, this method was used to determine the levels of positive strand RNA in 11 HCV positive hepatocellular carcinomas (HCC) and compared these with adjacent non-tumorous liver tissue. To confirm that the difference in viral titers is not related to variations in the amount of RNA used in the assay, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA was also assessed by competitive RT-PCR in all tissue extracts. Using this competitive assay it was determined that HCV RNA levels in the liver and tumor samples ranged from 10(3) to 10(6) molecules per microg of total RNA which is similar to previous reports. Interestingly, the amount of HCV in all the non-tumorous liver specimens were found to be significantly higher (P<0.05) than the surrounding tumors, while the GAPDH mRNA levels were found to be similar in both liver and tumor. Competitive RT-PCR is a sensitive, accurate and reliable method to determine HCV titers in clinical specimens. Using this method it was determined that malignant tumor cells harbor less HCV as compared with the surrounding non-tumorous liver cells.

Performance characteristics of the COBAS AMPLICOR hepatitis C virus MONITOR Test, version 2.0

We evaluated the performance characteristics of the COBAS AMPLICOR Hepatitis C Virus (HCV) MONITOR Test, version 2.0. Dilution studies using patient specimens demonstrated a lower limit of detection of 1,000 copies per milliliter. The assay was linear from 1,000 to 1 million HCV RNA copies per milliliter. Within-run precision and between-run precision were acceptable (approximately 0.100 and 0.14 SD for log10 [copies per milliliter]). A comparison of this version of the test (y), with the manual AMPLICOR HCV MONITOR Test, version 1.0 (x), yielded the following Deming regression equation: y = 1.004(+/- 0.04)x + 0.654(+/- 0.22); Sy/x¿D = 0.336; n = 92; r2 = 0.846; r = 0.920. Further comparison of the COBAS version 2.0 assay (x) with the QUANTIPLEX HCV bDNA Test (y) yielded the following Deming regression equation: y = 0.943 (+/- 0.130)x + 0.473 (+/- 0.717); Sy/x¿D = 0.194; n = 26; r2 = 0.600; r = 0.774. Version 2.0 detected the spectrum of HCV genotypes better than version 1.0.

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

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

Genotype and viral load as prognostic indicators in the treatment of hepatitis C

Interferon-alpha (IFN-alpha), either alone or in combination with ribavirin, is the standard treatment for patients with hepatitis C. However, most patients do not achieve a sustained remission with this treatment regimen. A number of studies have demonstrated that genotype, baseline viral load and/or a decrease in viral load early after treatment induction are the major predictive factors for response to treatment with IFN. Patients with hepatitis C virus (HCV) genotype 1 are more resistant to treatment with IFN, whereas low viral load at baseline and a marked decline in the HCV RNA level during the first 2-12 weeks of IFN therapy are associated with enhanced treatment efficacy. These variables could potentially be used to develop treatment algorithms that tailor therapies for specific clinical situations. Continued development and refinement of such algorithms would facilitate both the selection of patients who are most likely to benefit from therapy and the development of optimal treatment regimens for different patient groups. Predictive factors will also enable clinicians to identify subsets of patients who are not expected to respond well to current treatment. The development of new delivery methods for IFN that produce sustained antiviral pressure may provide a means of treating these previously difficult-to-treat patient groups.

Comparison between three quantitative assays in patients with chronic hepatitis C and their relevance in the prediction of response to therapy

To compare three quantitative assays measuring viral load in patients with chronic hepatitis C and to determine their value in predicting response to interferon (IFN) therapy, we analysed serum from 896 patients from eight European Centres using QUANTIPLEXtrade mark bDNA, MONITOR AMPLICORtrade mark and SUPERQUANTtrade mark assays. Analyses were performed on the same sample. Viral genotype was assessed using INNO-LiPA HCV II kits. Intercentre variations were observed that were related to the handling of specimens not processed and stored within 6 h of blood sampling. Among sera with optimal handling, a stronger correlation was observed between bDNA and SUPERQUANT (0.806) than between bDNA and MONITOR (0.677) and between MONITOR and SUPERQUANT (0.632). These discrepancies were greatest with genotype 2 (bDNA/SUPERQUANT= 0.772; bDNA/MONITOR=0. 456; SUPERQUANT/MONITOR= 0.299). This correlation was influenced by viraemia level and was better at lower viral loads. The proportion of sera with undetectable viral load was 15% with bDNA, 9.7% with MONITOR and 7.7% with SUPERQUANT. For the three measurements, the best cut-offs of sustained response to IFN treatment were located at their detection threshold. Among patients with viral load below the detection level, a sustained response was observed in 35% tested with bDNA, 38% with MONITOR and 80% with SUPERQUANT. Hence a stronger correlation was observed between bDNA and SUPERQUANT than between either of these assays and MONITOR. SUPERQUANT was the most sensitive assay and this greater sensitivity was associated with a better predictive value of treatment response.

Performance of an automated system for quantification of hepatitis C virus RNA

The Amplicor HCV Monitor test for quantitative determination of serum or plasma hepatitis C virus (HCV) RNA was modified recently and introduced onto the Cobas Amplicor instrument to automate fully amplification, detection and calculation of results. This new version (v2.0) was evaluated in a routine diagnostic laboratory. The sensitivity and reproducibility were assessed on well-characterized panels (Eurohep) and clinical samples. HCV RNA levels measured by the v2.0 Monitor test were about 1log(10) higher than those detected by the previous version test, and genotypes 1 and 3 were quantified with equal sensitivity. Within the linear dynamic range of 10(3) to 10(6) copies/ml, the coefficients of variation for both intra- and inter-assay reproducibility ranged from 1.9 to 2.95%. This test system was found to be a reliable and labor saving assay for the quantification of HCV RNA.

[Viral quantitation of hepatitis C virus: present and future]

INTRODUCTION

Hepatitis C virus (HCV) plasmatic load, also called HCV viremia, is expressed in copies per milliliter or viral particle equivalents per milliliter.

CURRENT KNOWLEDGE AND KEY POINTS

The methods used to measure HCV viremia are based on two principles: the quantitation of viral proteins (measure of antigenemia using monoclonal antibodies), and the quantitation of viral nucleic acid using PCR after reverse transcription (RT-PCR), or signal amplification (branched DNA). There is no relationship between viremia and liver histologic activity.

FUTURE PROSPECTS AND PROJECTS

The use of HCV quantitative viremia in a treatment algorithm, including other factors such as age, genotype, degree of viral genetic heterogeneity, and liver fibrosis score will help adapt therapeutic associations for each individual.

Ribonuclease-resistant RNA Controls (Armored RNA) for Reverse Transcription-PCR, Branched DNA, and Genotyping Assays for Hepatitis C Virus

Background: Comparison and evaluation of molecular diagnostic assays for the detection and quantification of hepatitis C virus (HCV) RNA have been limited by the lack of RNA controls and calibrators. Armored RNA® technology is a means for producing RNA that is completely protected from plasma ribonucleases. This method produces recombinant pseudoviral particles that are noninfectious and contain predefined RNA sequences.

Methods: A consensus 412-base sequence from the 5′NCR/Core region of HCV subtype 2b was derived from 34 individually sequenced HCV genotype 2b variants. A DNA fragment encoding the consensus HCV-2b sequence was synthesized de novo, cloned, and expressed as an Armored RNA control. The resulting HCV-2b Armored RNA (AR-HCV-2b) contained the complete HCV-2b consensus RNA sequence encapsidated within a protective protein coat.

Results: AR-HCV-2b was fully recoverable from human plasma incubated at 4 °C for &gt;300 days. The particles were tested in three clinical assay formats: AmplicorTM HCV Monitor 1.0, QuantiplexTM HCV RNA 2.0, and INNO-LiPATM HCV II. When added into seronegative, nonviremic plasma, AR-HCV-2b showed reproducible signals and linear dilutions in both the Amplicor and Quantiplex assays. AR-HCV-2b was correctly identified as subtype 2b in the INNO-LiPA line probe assay.

Conclusion: The HCV-2b Armored RNA control is a versatile, durable, ribonuclease-resistant viral RNA control that is compatible in three different clinical assay formats.

Clinical use of hepatitis C virus tests for diagnosis and monitoring during therapy

This article reviewed various methods used for the diagnosis and monitoring of HCV infection and discusses potential clinical applications. Substantial improvements have recently been made in assay technology. Moreover, the role of molecular testing in the clinical setting of hepatitis C is becoming better defined. The major challenge facing clinical laboratories is the further refinement, implementation, and standardization of optimized molecular tests, so that reliable data may be made available to clinicians. In turn, clinicians must understand the limitations of each methodology, including the variability of testing that may occur among different laboratories. As more experience is gathered, molecular testing will probably provide important data regarding the most effective use of current and future therapies for individual patients to achieve maximum benefit in the management of hepatitis C.

Quantification of hepatitis C virus RNA in serum by branched DNA-based signal amplification assays

The objective of the study was to compare the clinical sensitivity and specificity of versions 1.0 and 2.0 of the branched DNA (bDNA)-based hepatitis C virus (HCV) RNA quantification assay, and also to compare the values yielded by the two versions according to the HCV genotype. Serum samples from 268 patients tested routinely by a non-quantitative HCV RNA PCR assay (group A) were tested with version 2.0 of the bDNA assay. Samples from 342 HCV PCR-positive patients with chronic hepatitis C eligible for interferon treatment (group B) were tested with both version 1.0 and version 2.0 of the bDNA assay. Version 2.0 had a clinical sensitivity of 92% (95% confidence interval (CI): 87-97%) in group A and 89% (86-92%) in group B. In group B, the gain in sensitivity with bDNA 2.0 was 16% relative to bDNA 1.0 (P < 0.001). The log values of the two assays correlated with samples positive by both assays (r = 0.83, P < 0.0001), but the distribution of values was larger in samples containing HCV genotypes 2 and 3. The mean ratio of assay 2.0/assay 1.0 values was 1.69 +/- 1.44 (range: 0.33-13.43). The mean ratio was close to 1 with samples containing genotype 1 or 4, but ranged from 0.33 to more than 5. The mean ratio was close to 3 with samples containing genotype 2 or 3, and ranged from 0.5 to more than 13. HCV RNA levels were significantly lower in samples containing genotype 4 than in those containing other genotypes. Sera from 200 anti-HCV-negative, HCV RNA PCR-negative blood donors (group C), and from 164 anti-HCV-negative patients with symptoms of chronic liver disease (group D) were used to assess the clinical specificity of bDNA 2.0. In addition, samples with an HCV RNA titer between 0.2 (assay cutoff) and 0.5 MEq/ml from a group of 546 patients tested routinely for HCV RNA load by bDNA 2.0 (group E) were retested by bDNA 2.0 and by qualitative PCR. The specificity of bDNA 2.0 was 100% (98-100%) in group C and 99% (97-100%) in group D. Among the 41 samples from group E, 38 were positive by bDNA 2.0 retesting (36 were PCR-positive) and three were negative by bDNA 2.0 retesting (all were PCR-positive). It is concluded that version 2.0 of the bDNA assay is markedly more sensitive than version 1.0 and has a good specificity. In contrast with version 1.0, version 2.0 is not influenced by the HCV genotype. The relationship between values obtained with assays 1.0 and 2.0 on clinical specimens is not linear, indicating that HCV RNA titers cannot reliably be calculated from the results of version 1.0.