Extension of platelet shelf life from 4 to 5 days by implementation of a new screening strategy in Germany.

BACKGROUND: The Paul-Ehrlich-Institute analysed all fatalities due to bacterial infections between 1997 and 2007. Thereafter, the platelet shelf life was reduced to a maximum of 4 days after blood donation because the majority of all cases of severe transfusion-transmitted bacterial infections occurred with day 5 platelets. The current study compares the analytical sensitivity and the diagnostic specificity of four rapid bacterial detection procedures. METHODS: Nine transfusion-relevant bacterial strains were spiked in pooled platelets or apheresis platelets at a low concentration (10 CFU/bag). Samples were collected after day 3, day 4 and day 5 and investigated by four rapid bacterial detection methods (modified BacT/ALERT, Bactiflow, FACS method and 16s DNA PCR methods). RESULTS: Seven out of nine bacterial strains were adequately detected by BacT/ALERT, Bactiflow and PCR in apheresis platelets and pooled platelets after sample collection at day 3, day 4 and day 5. For three bacterial strains, analytical sensitivity was reduced for the FACS method. Two bacterial strains did not grow under the storage conditions in either pooled or apheresis platelets. CONCLUSIONS: A late sample collection on day 3, day 4 or day 5 after blood donation in combination with a rapid bacterial detection method offers a new opportunity to improve blood safety and reduce errors due to sampling., BacT/ALERT, Bactiflow or 16s ID-NAT are feasible for late bacterial screening in platelets may provide data which support the extension of platelet shelf life in Germany to 5 days.

The t(6;9) associated DEK/CAN fusion protein targets a population of long-term repopulating hematopoietic stem cells for leukemogenic transformation.

The t(6;9)-positive acute myeloid leukemia (AML) is classified as a separate clinical entity because of its early onset and poor prognosis. The hallmark of t(6;9) AML is the expression of the DEK/CAN fusion protein. The leukemogenic potential of DEK/CAN has been called into question, because it was shown to be unable to block the differentiation of hematopoietic progenitors. We found that DEK/CAN initiated leukemia from a small subpopulation within the hematopoietic stem cell (HSC) population expressing a surface marker pattern of long-term (LT) HSC. The propagation of established DEK/CAN-positive leukemia was not restricted to the LT-HSC population, but occurred even from more mature and heterogeneous cell populations. This finding indicates that in DEK/CAN-induced leukemia, there is a difference between 'leukemia-initiating cells' (L-ICs) and 'leukemia-maintaining cells' (L-MCs). In contrast to the L-IC cells represented by a very rare subpopulation of LT-HSC, the L-MC seem to be represented by a larger and phenotypically heterogeneous cell population.

Analysis of leukocyte binding to depletion filters: role of passive binding, interaction with platelets, and plasma components.

Since limited knowledge exists on the mechanisms which regulate cell binding to leukocyte removal filter surfaces, we investigated the binding patterns of leukocytes to individual layers of leukocyte depletion filters. After passage of 1 unit of whole blood, blotting of isolated filter layers on glass slides or elution of cells from filter layers revealed that most leukocytes were located within the first 10 of a total of 28 filter layers, peaking at layers 6 to 8, with granulocytes binding on average to earlier filter layers than lymphocytes. Leukocytes preincubated with inhibitors of actin activation showed unchanged distribution between filter layers, suggesting that cytoskeletal activation does not significantly contribute to their binding. When leukocytes were directly incubated with single filter layers, binding of up to 30% of input cells was recorded in the absence of Ca(2+). Immunohistological analyses showed colocalization of platelets and leukocytes, with co-clustering of platelets and leukocytes. Monocytes and to some degree lymphocytes but not granulocytes competed with platelets for filter binding. Precoating of filter layers with individual plasma components showed that hyaluronic acid, plasma type fibronectin, and fibrinogen all increased the binding of leukocytes compared with albumin coating. In conclusion, leukocytes can bind passively to filters in a process which does not require Ca(2+), which is independent of cytoskeletal activation and which may depend on individual plasma components. These results are of importance when new selective cell enrichment or depletion strategies through specific filters are envisaged.

Mutations in the putative HCV-E2 CD81 binding regions and correlation with cell surface CD81 expression.

The hepatitis C virus (HCV) envelope (E)2 protein interacts with the cellular receptor CD81 leading to modulation of B and T cell function. Recently, a higher binding affinity of subtype 1a in comparison with 1b derived E2 proteins for CD81 in vitro was described. The importance of mutations within the putative CD81 binding regions of different HCV geno-/subtypes in correlation with CD81 expression is unknown. In the present study, CD81 expression on blood lymphocytes of patients with chronic hepatitis C infected with different HCV geno-/subtypes were analysed by fluorescence activated cell sorter analyses. In addition, the putative CD81 binding regions on the E2 gene comprising the hypervariable region (HVR)2 were analysed by direct sequencing. CD81 expression on CD8(+) T-lymphocytes from patients infected with subtype 1a (n = 6) was significantly higher in comparison with subtype 1b (n = 12) and 3 (n = 5) infected patients before and during antiviral therapy (P = 0.006; P = 0.021, respectively). Sequencing of the putative CD81 binding regions in the E2 protein comprising the HVR2 (codon 474-495 and 522-552 according to the HCV-1a prototype HCV-H) showed a highly conserved motif within HVR2 for subtype 1a isolates and an overall low number of mutations within the putative CD81 binding regions, whereas numerous mutations were detected for subtype 1b isolates (12.0 vs 23.6%). HCV-3 isolates showed an intermediate number of mutations within the putative binding sites (19.2%; P = 0.022). In conclusion, the highly conserved sequence within HVR2 and putative CD81 binding sites of subtype 1a isolates previously associated with a high CD81 binding affinity in vitro is correlated with high CD81 expression on CD8(+) T-lymphocytes in vivo.

Dynamics of hepatitis C virus quasispecies turnover during interferon-alpha treatment.

Interferon-alpha (IFN) has been shown to accelerate the evolution of hepatitis C virus (HCV) variants (quasispecies) in nonresponder patients. Different sensitivities of HCV variants to IFN are discussed as a possible mechanism. In the present study, quasispecies were investigated in detail by a newly established and validated direct solid-phase sequencing of the hypervariable region 1 (HVR1), during the initial 3 months of IFN therapy. According to single strand conformation polymorphism (SSCP) analysis, 14 of 26 (54%) virologic nonresponders with quasispecies evolution were identified. Six representative patients with SSCP changes were selected for frequent HVR1 sequencing. Pre-existing variants were identified by cloning and sequencing of the pretreatment serum HCV sample. In one patient the major type was substituted by a minor variant within 3 days of treatment while in the majority of patients the pretreatment major type did not decline before days 26-57 of treatment. Total serum HCV RNA levels remained constant in all patients. In conclusion, although quasispecies evolution during IFN therapy is common, it occurs after a wide range of time intervals after initiation of therapy. Thus, nonresponse to IFN cannot exclusively be explained by changes in the quasispecies.

Quasispecies heterogeneity of the carboxy-terminal part of the E2 gene including the PePHD and sensitivity of hepatitis C virus 1b isolates to antiviral therapy.

Two regions within the HCV genome, hypervariable region 1 (HVR1) within the envelope (E)2 region and the PKR-binding domain (PKRbD) comprising the interferon sensitivity determining region (ISDR) within the nonstructural (NS)5A protein, have been reported to correlate with the outcome of antiviral treatment. Recently, a PKR/eIF2alpha phosphorylation homology domain (PePHD) within the E2 protein of HCV-1 isolates was described to inhibit PKR in vitro. PePHD deleted HCV-1 mutants remain capable of binding PKR to some extent while inhibition of PKR was found to be abolished by carboxy-terminal truncated E2 protein. The importance of mutations and quasispecies heterogeneity within the carboxy-terminal part of the E2 protein comprising the PePHD of HCV-1b is unknown. Therefore, the carboxy-terminal part of the HCV E2 gene (codons 618-746) including the PePHD was analyzed by sequencing of PCR products and individual clones of 41 HCV-1b-infected patients with sustained (SR, n = 12), end-of-treatment (ETR, n = 10), or no virological (NR, n = 19) response to antiviral therapy. Two highly conserved regions (codons 658-673 comprising the PePHD and codons 675-704) and one variable region (codons 705-720) were detected within the carboxy-terminal part of E2. No significant correlation of specific mutations or number of mutations with treatment response was observed for the PePHD and the carboxy-terminal part of the E2 protein. Phylogenetic and conformational analyses showed no specific clusters related to treatment outcome. Calculation of genetic complexity and diversity based on nucleotide sequence analyses of 20 individual clones per patient showed no differences between matched SR, ETR, and NR patients. However, calculation of genetic complexity and diversity on the basis of amino acid sequences showed significantly lower normalized Shannon entropy as well as mean Hamming distances for SR patients than in ETR and NR patients (P = 0.029 and P = 0.027, respectively). This indicates that patients achieving a sustained virological response to interferon-alpha-based antiviral therapy may elicit more effective immunological pressure, resulting in continuous clearing of individual variants of HCV quasispecies.

Interferon alfa down-regulates CD81 in patients with chronic hepatitis C.

CD81 protein has been shown to bind hepatitis C virus (HCV) envelope 2 (E2) glycoprotein in vitro and may act as a (co)receptor for HCV. Regulation of CD81 expression by interferon alfa (IFN-alpha) and ribavirin could thereby affect the response to antiviral therapy. In the present study, the effects of IFN-alpha and ribavirin on CD81 protein and CD81 mRNA were assessed in peripheral blood lymphocytes (PBL) and isolated human hepatocytes by fluorescence-activated cell sorter (FACS) analysis and real-time polymerase chain reaction (PCR), respectively. In addition, regulation of CD81 in PBL was investigated in 10 patients treated with combination therapy. Incubation with IFN-alpha (50 U/mL) down-regulated total CD81 in PBL (81.7 +/- 11.6% of control; P =.003) and in isolated human hepatocytes (91.6 +/- 8.1% of control; P =.034). Incubation with IFN-alpha with and without ribavirin (2.2 microg/mL) significantly reduced cell surface-associated CD81 protein (83.9 +/- 10.3% of control; P =.003). PBL of untreated patients chronically infected with HCV had significantly higher levels of total CD81 protein compared with PBL obtained from healthy donors (631.1 +/- 93.3 vs. 538.9 +/- 95.2 relative fluorescence units [RFU]; P =.030). Pretreatment cell surface-associated CD81 protein was lower in patients infected with genotype HCV-3 than those infected with HCV-1 (111.8 +/- 15.0 vs. 162.0 +/- 41.3 RFU; P =.019). Furthermore, cell surface-associated CD81 protein was lower 4 weeks after initiation of therapy in patients with an initial virologic response compared with initial virologic nonresponders (110.5 +/- 8.5 vs. 139.8 +/- 27.5 RFU; P =.057). In conclusion, IFN-alpha and ribavirin regulate CD81 expression in vitro and in vivo. CD81 expression correlates with HCV genotype and initial virologic response in patients with chronic hepatitis C.

Comparative sequence analysis of the core- and NS5-region of hepatitis C virus from tumor and adjacent non-tumor tissue.

The sequence variability within the core- and non-structural 5 (NS5)-region of the hepatitis C virus (HCV) was investigated in tumor and non-tumor tissue of 8 patients with HCV-associated hepatocellular carcinoma (HCC). Analyses of multiple clones containing polymerase chain reaction-amplified HCV sequences revealed a significantly higher variability within the core-region of tumor tissue isolates than of isolates from non-tumor tissue. Mutant sequence diversity ranged from silent mutations, as well as amino acid substitutions, appearance of in frame stop codons and deletions leading to frame-shifts. In contrast, the variability of the NS5-region sequences between isolates from tumor and non-tumor tissue was not significantly different. These observations might have important implications on the pathology of HCV, especially its potential tumorigenicity.

Hepatocellular proliferation in patients with chronic hepatitis C and persistently normal or abnormal aminotransferase levels.

BACKGROUND/AIMS: Some patients chronically infected with the hepatitis C virus (HCV) have persistently normal alanine aminotransferase (ALT) levels while progressive liver damage is observed histologically. In the present study, we compared the rate of proliferation, apoptosis, and necrosis in liver biopsy specimens of patients with persistently normal or elevated ALT levels. METHODS: Fourteen patients with persistently normal and 14 age- and sex-matched patients with elevated ALT levels were enrolled. Proliferation was detected using anti-Ki 67 in 10-microm liver biopsy specimens of the patients. Apoptosis was measured by TUNEL-assay and by monoclonal anti-M30 directed against caspase-cleaved cytokeratin 18 filaments. RESULTS: The mean number of anti-Ki 67 positive hepatocytes was lower in patients with persistently normal aminotransferases (3.1 +/- 2.8/10(3) vs 10.8 +/- 8.8/10(3) hepatocytes, p<0.0011) and was correlated with serum ALT (r=0.86, p<0.01) and aspartate aminotransferase levels (r=0.83, p<0.01). The rate of apoptosis detected by TUNEL assay was low and not different between patients with persistently normal and elevated aminotransferases. Staining with anti-M30 revealed a granular staining pattern and showed a trend towards higher cell death rates in patients with elevated aminotransferase levels (apoptotic hepatocytes with >75% staining: 3.97 +/- 6.24/10(3) hepatocytes vs 13.65 +/- 19.41/10(3) hepatocytes; p=0.08). CONCLUSIONS: Patients with chronic hepatitis C and normal aminotransferases have significantly lower hepatocyte proliferation rates and show a trend towards lower apoptosis rates compared with patients with elevated aminotransferases.

Prospective follow-up of patients with GBV-C/HGV infection: specific mutational patterns, clinical outcome, and genetic diversity.

An association between a specific mutational pattern within the nonstructural (NS)3 region of GB virus-C/hepatitis G virus (GBV-C/HGV) genome and fulminant hepatic failure has been suggested recently. The mutational pattern consists of 3-6 nucleotide mutations of which one is leading to an amino acid exchange. In the present study, patients with GBV-C/HGV mono-infection (n = 24) or GBV-C/HGV and HCV co-infection (n = 20) were investigated prospectively. In 6/44 patients (14%) the mutational pattern within GBV-C/HGV NS3 previously associated with fulminant hepatic failure was identified by direct sequence analysis of the NS3 region. All 44 patients were asymptomatic clinically and had normal liver functions at initial presentation and after a median follow-up of 2.2 years. In 22/24 patients with GBV-C/HGV mono-infection and all patients with GBV-C/HGV and HCV co-infection GBV-C/HGV RNA remained detectable at the end of the study period, whereas two patients infected with GBV-C/HGV alone became negative for GBV-C/HGV RNA and developed GBV-C/HGV anti-E2 antibodies indicating recovery from GBV-C/HGV infection. Aminotransferase levels remained elevated or became normal independent of the persistence of serum GBV-C/HGV RNA. The median rate of nucleotide substitutions in GBV-C/HGV mono-infected and HCV co-infected patients was 3.4 x 10(-3) and 3.2 x 10(-3) per site per year, respectively. In conclusion, the prevalence of the mutational pattern within NS3 region of GBV-C/HGV associated previously with fulminant hepatic failure is about 14% and not associated specifically with severe liver disease. Over a median follow-up of 2.2 years less than 5% of patients cleared spontaneously GBV-C/HGV and no correlation between viraemia and elevated liver enzymes was observed.

Mutations within the E2 and NS5A protein in patients infected with hepatitis C virus type 3a and correlation with treatment response.

Defined regions of hepatitis C virus (HCV) envelope 2 (E2), PePHD, and nonstructural 5A (NS5A) protein (PKR-binding domain) have been shown to interact with interferon alfa (IFN-alpha)-inducible double-stranded RNA-activated protein kinase (PKR) in vitro, suggesting a possible mechanism of HCV to evade antiviral effects of IFN-alpha. The clinical correlation between amino acid mutations within the E2 PePHD or the NS5A PKR-binding domain and response to antiviral treatment in HCV-3a-infected patients is unknown. Thirty-three patients infected with HCV-3a isolates were treated with IFN-alpha with or without ribavirin. The carboxyterminal half of E2 and of the NS5A gene were sequenced. Sixteen patients achieved a sustained virological response (SR), 6 patients an end-of-treatment response with relapse thereafter (ETR), and 11 patients were nonresponders (NR). Within the PePHD of the E2 protein 0.5 (range, 0-2) mutations were observed in SR patients, whereas the number of mutations in ETR or NR patients was 0.2 (0-1). Quasispecies analyses showed almost no heterogeneity. The mean number of mutations within the PKR-binding domain of the NS5A protein was 1.6 (range, 0-4) in SR patients, 1 (0-2) in ETR patients, and 1.6 (0-3) in NR patients. Patients with higher numbers of mutations within the E2 or NS5A region showed a trend towards lower pretreatment viremia. Phylogenetic and conformational analyses of E2 or NS5A sequences allowed no differentiation between sensitive and resistant isolates. However, mutations within the E2 PePHD in SR patients were frequent, and hydrophobic mutations within the hydrophilic area of PePHD at codon 668 and 669 were exclusively observed in sustained virological responders.

Mutations in the protein kinase-binding domain of the NS5A protein in patients infected with hepatitis C virus type 1a are associated with treatment response.

An interaction of the hepatitis C virus (HCV) NS5A protein with the interferon (IFN)-alpha-inducible double-stranded RNA-activated protein kinase (PKR) was demonstrated in vitro. The clinical correlation between amino acid mutations within the HCV NS5A region and response to antiviral treatment is controversial. Thirty-two patients chronically infected with HCV-1a, who were treated with IFN-alpha with or without ribavirin, were studied. The carboxy-terminal half of HCV NS5A was sequenced and was investigated by phylogenetic and conformational analyses. Eight patients achieved a sustained virologic response. An end-of-treatment response but relapse thereafter was observed among 8 patients, whereas 16 patients were nonresponders. The median number of mutations within the PKR-binding domain but not within the previously described IFN sensitivity-determining region was significantly higher for patients with sustained (3 mutations [range, 1-5]) or end-of-treatment (4 mutations [range, 1-5]) virologic response than for nonresponders (2 mutations [range, 0-3]) (P=.0087). Phylogenetic and conformational analyses of NS5A sequences allowed no differentiation between sensitive and resistant strains.

Quantification of the initial decline of serum hepatitis C virus RNA and response to interferon alfa.

Although several virus- and host-related predictive factors for the response to interferon alfa (IFN-alpha) have been defined in patients with chronic hepatitis C, no pretreatment parameter can definitely predict the response to antiviral treatment. Assessment of the initial response by quantification of serum hepatitis C virus RNA before and 4 weeks after initiation of therapy may be a clinically applicable and reliable parameter to predict long-term response. Therefore, the aims of the present study were to test the predictive value of a decline in HCV RNA of at least 3 log in the first 4 weeks of treatment (deltaHCV RNA) in patients treated with 3 x 10(6) units of recombinant IFN-alpha2a (rIFN-alpha2a) three times per week subcutaneously and to compare deltaHCV RNA with other established predictive factors, such as HCV genotype and pretreatment viremia. Serum HCV RNA was measured by a validated quantitative reverse transcription-polymerase chain reaction (RT-PCR). Geno/subtyping of HCV was performed by direct sequencing of the nonstructural (NS) 5B region of PCR-amplified isolates and subsequent phylogenetic analysis. Stable HCV RNA levels (deltaHCV RNA < or = 1 log) within the first 4 weeks of IFN-alpha treatment were present in 42 of 70 patients. A decline in HCV RNA levels between 1 to 3 log and more than 3 log was observed in 9 (13%) and 19 patients (27%), respectively. In 21 of 70 patients (30%), HCV RNA was not detectable at the end of 12 months' treatment. Three of 26 patients (11%) with a pretreatment viremia of < or = 10(6) copies/mL (all HCV subtype 3a) and 6 of 44 patients (14%) with a pretreatment viremia of > 10(6) copies/mL (HCV subtypes 1b, 2a, 2c, 3a [two patients], and 4) achieved a virological sustained response to interferon-alpha2a treatment. All patients with a virological sustained response had an initial deltaHCV RNA of more than 3 log. In a stepwise discriminant-function analysis, the initial deltaHCV RNA was confirmed as the strongest predictor of virological sustained response (P < .0001). In conclusion, the data of the present study suggest that IFN-alpha treatment can be terminated after 4 weeks in patients with a decrease in HCV RNA levels of less than 3 log, when apparent HCV eradication is considered the therapeutic target. The predictive value of deltaHCV RNA clearly exceeds the significance of HCV genotype and pretreatment viremia as predictors of successful IFN-alpha treatment.

Quantification of hepatitis C virus RNA by RT-PCR in comparison to the branched DNA method.

INTRODUCTION: Quantification of hepatitis C virus (HCV) serum viremia levels is an important measure to predict and monitor response to interferon-alpha therapy as well as to predict clinical outcome. We were interested to compare the most widely used HCV quantification methods, quantitative RT-PCR (qRT-PCR) and the branched DNA (bDNA) method, with respect to sensitivity and reliability. RESULTS: In the present study, 101 serum samples from patients chronically infected with HCV were simultaneously quantified by an in-house reverse transcriptase (RT)-PCR assay and the branched DNA Quantiplex HCV RNA kit 1.0 and 2.0. The concentration of HCV RNA molecules/ml serum ranged from 1.5 x 10(4) to 1.0 x 10(8) as assessed by our quantitative (q)RT-PCR. Serum concentrations of HCV-genotype 1 were significantly higher when measured with bDNA 1.0 compared to bDNA 2.0 and qRT-PCR, whereas measurements by qRT-PCR and bDNA 2.0 were concordant. Measurements of genotypes 2 and 3 by bDNA 2.0 were significantly higher than by bDNA 1.0. Significantly lower measurements were obtained for genotype 3 by qRT-PCR in comparison to bDNA 2.0. CONCLUSION: Despite subtype-specific differences, there is clinically sufficient agreement in measurements between qRT-PCR and bDNA of HCV RNA concentrations. However, with respect to the therapeutic monitoring of the individual patient, kits and methods should not be exchanged.

Phylogenetic analysis of hepatitis C virus isolates and their correlation to viremia, liver function tests, and histology.

Nucleotide sequence analysis of hepatitis C virus (HCV) strains showed substantial variability leading to a classification into several genotypes and subtypes. The data correlating HCV genotypes and subtypes with hepatitis C viremia levels, demographic characteristics of patients (age, mode of transmission, duration of infection), and severity of liver disease are conflicting. The interpretation of several studies is further complicated because the molecular methods used lacked specificity for genotyping/subtyping and underestimated viremia levels, especially in patients infected with HCV genotypes 2 and 3. In the present study we investigated 97 consecutive patients with chronic hepatitis C using molecular "gold standard" methods. HCV subtyping was performed by sequence and phylogenetic analysis of the nonstructural (NS)-5 region and serum HCV-RNA concentration was assessed by a validated genotype-independent quantitative reverse-transcription-polymerase chain reaction assay using an internal RNA standard. Patients infected with subtypes HCV-1b, HCV-2a-c, and HCV-4 were older than patients infected with HCV-1a and HCV-3a. Serum HCV-RNA levels ranged from 1.5 x 10(4) to 1.0 x 10(8) copies/mL with no significant differences between median serum HCV-RNA concentrations in patients infected with different genotypes/subtypes. Although patients infected with HCV-1b were older, no biochemical or histological evidence was obtained that this subtype is associated with more severe liver disease. Furthermore, the present study showed a lack of correlation between the serum HCV-RNA concentration, biochemical parameters, and liver histology. The median serum HCV-RNA levels in patients with chronic persistent hepatitis, chronic active hepatitis, and liver cirrhosis were 5.0 x 10(6) copies/mL, 2.5 x 10(6) copies/mL, and 5.0 x 10(6) copies/mL, respectively. These differences were not significant. In conclusion, using optimized and validated molecular techniques, the present cross-sectional study showed no correlation between HCV genotypes/subtypes, viremia, liver function test results, and histology.

Comparison of two quantitative hepatitis C virus reverse transcriptase PCR assays.

A quantitative hepatitis C virus reverse transcriptase PCR (HCV RT-PCR) assay established in our laboratory was compared with the Roche Amplicor HCV Monitor test kit for agreement of test results and intra-assay variability. Both assays rely on reverse transcription and amplification of extracted RNA from patients' sera together with an internal RNA standard derived from the 5'-noncoding region of HCV. A panel of clinical serum samples (n = 33) was quantitatively analyzed in parallel by both test systems. The methods demonstrated substantial agreement between 1 x 10(3) and 5 x 10(5) HCV RNA molecules per ml of serum. However, with sera containing more than 5 x 10(5) copies per ml, according to our in-house assay, the results diverged on average in a nonacceptable range of 2 orders of magnitude. Our in-house HCV RT-PCR assay measured up to 5 x 10(7) HCV-RNA molecules per ml in some serum samples. However, the Roche Amplicor HCV Monitor test kit did not detect more than 2 x 10(6) molecules in any of the serum samples tested. After dilution of serum samples prior to testing, an approximately 0.5 order of magnitude more HCV RNA molecules was detected by the Roche HCV test kit in sera containing high copy numbers (> 5 x 10(5) RNA copies according to the in-house assay). The in-house PCR and the Roche Amplicor HCV Monitor test kit revealed coefficients of variation of 6.2 and 7.5%, respectively.

Effect of interferon alfa on the dynamics of hepatitis C virus turnover in vivo.

In about 30% to 40% of patients with chronic hepatitis C, treatment with recombinant interferon alfa (r-IFN alpha) causes a decrease of serum aminotransferases and hepatitis C virus (HCV) RNA. The antiviral mechanism of interferon alfa (IFN alpha) in vivo is unknown. From serial measurements of serum HCV-RNA concentrations following IFN alpha induced perturbation of the balance between virus production and clearance, we obtained kinetic information on the pretreatment steady-state of HCV. In patients with chronic hepatitis C responding to IFN alpha, HCV-RNA declined exponentially with a half life of approximately 2 days. Modeling of the data predicts that in patients with chronic hepatitis C responding to IFN alpha this cytokine predominantly acts as an inhibitor of de novo infection of susceptible cells. HCV is released from infected cells with a mean half life of 2.7 +/- 1.3 days, whereas the clearance rate from serum is faster (mean half life, 0.7 +/- 0.4 days). The minimum virus production and clearance per day in patients with chronic hepatitis C was calculated to be 6.7 x 10(10) virions/d (range, 0.2 to 43.8 x 10(10) virions/d). These values showed no correlation with the HCV genotype, aminotransferase levels, or the histological activity as assessed before the administration of r-IFN alpha. Simultaneous kinetic analysis of serum aminotransferases as surrogate markers of hepatocyte integrity revealed half lifes for the release of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) from hepatocytes of 4.7 +/- 3.8 and 3.0 +/- 3.5 days, respectively. The half life data for HCV in chronically infected patients are remarkably similar to recently published data on human immunodeficiency virus type 1 (HIV-1) suggesting that both RNA viruses replicate continuously and highly productive in vivo. The turnover rates explain the rapid generation of viral diversity and the opportunity for viral escape phenomena from the host immune surveillance.

Hepatitis C virus sequences encoding truncated core proteins detected in a hepatocellular carcinoma.

RNA was specifically extracted from tumor and peritumor tissue of a hepatitis C virus (HCV)-associated hepatocellular carcinoma after microdissection. RT-PCR products of the HCV 5'-noncoding (NC), core and nonstructural (NS)-5 gene were examined. Nucleotide sequences of the core region derived from the tumor tissue revealed deletions and mutations resulting in truncated proteins. Peritumor and serum HCV sequences were unaffected.

Risk factors for the transmission of hepatitis C.

BACKGROUND: Due to the availability of testing for antibodies to the hepatitis C virus (anti-HCV) and with the use of the polymerase chain reaction (RT-PCR) to detect HCV-RNA, more sensitive and specific measures can be applied to assess routes of HCV transmission. The aim of the present study was to investigate possible risk factors for transmission of HCV. METHODS: 160 consecutive patients with chronic hepatitis C (mean age 47.1 +/- 14.1 yr) attending a hepatology out-patient clinic were interviewed to identify transmission risk factors. Genotyping of HCV isolates was performed by direct sequencing of RT-PCR products in the 5'-noncoding and the NS-5 region. RESULTS: The risk factors of HCV infection were as follows: transfusion of blood or blood products 34.4%, intravenous drug abuse 20.6%, heterosexual contact 3.8%, occupational risk 1.9% and tattoo 0.6%. In 62/160 (38.7%) the route of transmission remained unknown. In one HCV-infected couple we analyzed the nucleotide sequences of the NS-5 region of the respective HCV isolates and found almost complete sequence homology (> 97%). The majority of patients with post-transfusional or unknown mode of transmission were infected with genotype HCV-1a and -1b, while in 6/10 patients with previous i.v. drug abuse, genotype HCV-3a was present. We found no evidence that the mode of disease acquisition influences the course of liver disease. CONCLUSION: The majority of patients with chronic hepatitis C have a classical parenteral transmission risk factor. In our study, no source of HCV acquisition was identified in 38.7% of patients. It may well be that the major factors in these "sporadic" HCV infections are variations on the known risk factors. However, since the proportion of these cases is rather high, further attention should be on alternative and as yet unclear transmission routes.

Evaluation of a reverse hybridization assay for genotyping of hepatitis C virus.

BACKGROUND/AIMS: Several strains of the hepatitis C virus exist; distinct genotypes and subtypes can be identified by sequence comparison of the viral genomes. Recent evidence that the genotype/subtype of hepatitis C virus may influence the clinical course of chronic hepatitis C and the response to interferon-alpha therapy for this disease suggests that methods to identify the genotype may become clinically useful. In the present study we evaluated a recently introduced reverse hybridization assay. METHODS: HCV-RNA was isolated from serum samples from 61 consecutive patients attending our out-patient clinic and subsequently sequenced in the 5'-noncoding and the nonstructural-5 region by the dideoxynucleotide chain termination method. HCV-genotyping was performed by phylogenetic analysis of nonstructural-5 sequences. The amplification product for the reverse hybridization assay was obtained by "nested" polymerase chain reaction using biotinylated primers corresponding to the 5'-noncoding region. The assay is based on hybridization of the resulting polymerase chain reaction product with oligonucleotide probes immobilized as parallel lines on membrane strips. RESULTS: According to the phylogenetic analysis of the nonstructural-5 region the prevalence of hepatitis C virus subtypes was as follows: 1a 18%, 1b 51%, 2a 3%, 2b 3%, 2c 7% and 3a 18%. The reverse hybridization assay correctly identified each hepatitis C virus genotype (1, 2, and 3). However, differentiation of hepatitis C virus subtypes was insufficient. 1/11 HCV-1a isolates was incorrectly classified by the reverse hybridization assay as HCV-1b and vice versa 3/31 HCV-1b isolates as HCV-1a. Classification of hepatitis C virus subtypes 2a, 2b and 3a was correct, but 4/4 HCV-2c isolates were misinterpreted by the assay as HCV-2a. CONCLUSIONS: The reverse hybridization assay can differentiate between hepatitis C virus genotypes 1, 2, and 3, but is not completely reliable for hepatitis C virus subtyping.