Molecular biology of the hepatitis C viruses: implications for diagnosis, development and control of viral disease

Genotypes and titers of hepatitis C virus for predicting response to interferon in patients with chronic hepatitis C

Interferon induces remission in about 50% of patients with chronic hepatitis C, but it is difficult to predict which patients will respond. Host and viral factors were evaluated for correlation with response to interferon in patients with chronic hepatitis C. Recombinant interferon alpha-2b with a total dose of 480-560 million units was given to 136 patients, of whom 74 (54%) responded. Genotypes of hepatitis C virus (HCV) in sera, I, II, III, IV, and V, were determined by polymerase chain reaction (PCR) with type-specific primers. In 72 patients, pretreatment levels of HCV RNA were titrated by PCR in serial tenfold dilutions of RNA extracted from serum. Response to interferon occurred in 34 (40%) of 85 patients infected with HCV of genotype II, less frequently than in 22 (85%) of 26 with genotype III (P < 0.001) or in 7 (70%) of 10 with genotype IV. Of 51 patients with genotype II HCV, 6 of 8 (75%) with HCV RNA titers < 10(6) responded, more frequently than 4 of 43 (9%) with titers > or = 10(6) (P < 0.001). Responders were younger than non-responders (45.7 +/- 11.7 vs. 50.3 +/- 9.6 yr) and had received transfusions less frequently (26/74 or 35% vs. 37/62 or 60%, P < 0.01). Response to interferon correlated inversely with the severity of liver histopathology. These results indicate that response to interferon is influenced by HCV genotypes and pretreatment levels of HCV RNA in serum.

Hepatitis C virus-RNAs in plasma and in peripheral blood mononuclear cells of hemophiliacs with chronic hepatitis C: evidence for viral replication in peripheral blood mononuclear cells

Hemophiliacs who have been exposed to unheated and/or dry heated pooled clotting factor concentrates are at high risk of chronic hepatitis C. Although the mechanism and site of hepatitis C virus (HCV) replication are not yet known, HCV is thought to replicate through a complementary negative RNA strand, as has been shown for flaviviruses. The detection of negative RNA strands has therefore been regarded as a marker of replication. We investigated the prevalence of HCV-RNA and of negative HCV-RNA strands in peripheral blood mononuclear cells (PBMC) and plasma of hemophiliacs. Forty-three of 47 patients studied (91%) had anti-HCV antibodies and in 36 patients HCV-RNA was detectable in PBMC. In one group of 20 patients negative HCV-RNA strands were present in PBMC and 10 of these patients also had negative HCV-RNA strands in plasma. In another group of nine patients HCV-RNA was detected in PBMC, although cDNA synthesis was carried out in the absence of primers. Only in two of these nine patients negative and positive HCV-RNA strands were demonstrated specifically in PBMC using a modified reverse transcription step. If the presence of negative HCV-RNA strands can be considered as marker of viral replication, the findings indicate that HCV can replicate in PBMC. Furthermore, in certain patients it is impossible to use the currently available technique to detect selectively positive or negative HCV-RNA strands.

Conservation of hepatitis C virus 5' untranslated sequences in hepatocellular carcinoma and the surrounding liver

Persistent infection by hepatitis C virus is a major risk factor for the development of hepatocellular carcinoma, but the mechanism of hepatocarcinogenesis is unknown. To study the association of hepatitis C virus with hepatocellular carcinoma, we sequenced part of the 5' untranslated region of hepatitis C virus from the tumor tissue and the surrounding nontumorous liver of three patients with hepatocellular carcinoma. No sequence differences between tumor-derived and liver-derived hepatitis C virus isolates were detected. The conservation of the 5' untranslated region of hepatitis C virus--not only in infected hepatocytes, but also in neoplastic cells--suggests that the regulatory elements at the 5' terminus of the viral genome play an important role in the pathobiology of hepatitis C virus.

Analysis of the core and E1 envelope region sequences of a novel variant of hepatitis C virus obtained in Indonesia

Hepatitis C virus (HCV) is currently classified into 6 major types, HCV-1 through -6, each of which can be further divided into a few subtypes, e.g., HCV-1a, -1b, -1c, etc., on the basis of sequence variation of the viral genome. The core and E1 envelope regions of HCV genome were amplified from sera of Indonesian patients using reverse transcription-polymerase chain reaction. Sequence analysis of both core and E1 regions followed by molecular evolutionary phylogenetic analysis identified a novel sequence variant of HCV-1 (Td-6). Antibodies in the serum from which Td-6 was isolated reacted only marginally to the core protein of HCV-J, a representative strain of HCV-1b, despite strong antibody response against a mixture of the core, NS3 and NS4 proteins of HCV-1a. The possible mechanism for the diminished reactivity of the antibodies in the serum to the core protein of HCV-J is discussed.

Detection of hepatitis C virus antigen by immuno-histochemical staining: a histological marker of hepatitis C virus infection

Hepatitis C virus has been recognized as a major cause of non-A, non-B viral hepatitis. Although serologic tests have been commercialized, no specific histological or immuno-histochemical markers for hepatitis C virus infection are available for routine use. In an effort to detect hepatitis C virus antigen in liver tissue we investigated the immuno-reactivity to monoclonal antibodies on frozen liver tissue from a chimpanzee and patients with chronic non A, non B hepatitis. Monoclonal antibodies were developed in mice immunized with a synthetic peptide derived from hepatitis C virus core antigen. One monoclonal antibody was reactive and showed typical cytoplasmic granules in chimpanzee hepatocytes. Using this monoclonal antibody a similar staining pattern was found in the liver biopsies of 21 out of 28 chronic non-A, non-B hepatitis patients, positive for hepatitis C virus-RNA and anti-HCV. The granular immuno-reactivity was abolished after pre-incubation of this monoclonal antibody with infected chimpanzee liver or with hepatitis C virus synthetic peptide but not with normal chimpanzee or human liver tissue. There was no reactivity in four patients with hepatitis C virus-RNA-negative, anti-HCV-positive chronic non-A, non-B hepatitis, in 11 patients with chronic type B hepatitis or in 12 hepatitis C virus-RNA-negative, anti-HCV-negative patients with various liver diseases. However, staining was found in three out of four additional chronic type B hepatitis patients suspected of co-infection with non-A, non-B agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus genotypes are not responsible for development of serious liver disease

Although hepatitis C virus (HCV) is known to have at least four kinds of genotypes, no clear relationship has yet been established between the genotype and the severity of liver disease. Therefore, we determined HCV genotypes in sera of 251 Japanese patients with type C chronic liver disease, using polymerase chain reactions with six independent primers. One set of primers and a probe derived from 5'-noncoding region of HC-J1 was supposed to detect all four genotypes, while the other five were devised to detect each of the genotypes. Among the patients, the major genotype was type II (69%) and the second most common was type III (18%). Type IV was found in 7%, while none had type I genotype. There was no significant difference in the distribution of any genotype among different stages of liver disease, although the ratio of type II to type III tended to be higher in the group of cirrhosis and hepatocellular carcinoma than in the chronic hepatitis group (5.5 vs 3.0). The amounts of HCV RNA were significantly greater in patients with type II (P < 0.001) compared with those with types III and IV. However, HCV concentrations of each genotype were not associated with the disease status. These results suggest that HCV genotypes are unlikely to be responsible for the development of more serious liver disease.

Quantitative detection of hepatitis C virus genome in liver tissue and circulation by competitive reverse transcription-polymerase chain reaction

We quantified hepatitis C virus RNA in 25 Japanese patients with chronic type C liver disease by competitive reverse transcription-polymerase chain reaction. The amount of the viral RNA in the serum (2 x 10(5)-2 x 10(8) copies/ml) correlated with that in the liver tissue (10(8)-10(11) copies/g) (N = 23, r = 0.727, P < 0.0001). One gram of the infected liver tissue contained 10(2)-10(4) (geometric mean, 10(3), N = 23) times as many copies of the viral RNA as did 1 ml of the serum. Liver tissues of chronic aggressive hepatitis contained significantly higher amounts of the viral RNA than those of chronic persistent hepatitis (P < 0.05). These observations suggested that this method is useful to evaluate viral amount, and the amount of the circulating hepatitis C virus RNA could be used as a marker of the intrahepatic viral amounts, which might contribute to disease activity.

Isolation of hepatitis C virus RNA from serum for reverse transcription-PCR

Standard multistep extraction and isolation of RNA for hepatitis C virus (HCV) reverse transcription (RT)-PCR are impractical for routine use in clinical laboratories. We compared three simple commercially available methods for RNA isolation (RNAzol B, TRISOLV, and ULTRASPEC; Biotecx Laboratories, Houston, Tex.) and a total nucleic acid isolation method (IsoQuick; MicroProbe Corp., Garden Grove, Calif.) for the recovery of HCV RNA from sera obtained from 12 viremic patients for RT-PCR. RNAzol B, TRISOLV, ULTRASPEC, and IsoQuick extraction methods detected 87.5, 79.2, 33.3, and 58.3% of the paired positive samples, respectively. The method used for isolation of RNA is an important concern when optimizing HCV RT-PCR.

Identification of hepatitis C virus subtype 3b (HCV-3b) among Japanese patients with liver diseases using highly efficient primers for reverse transcription-polymerase chain reaction

With a reverse transcription-polymerase chain reaction method that utilized highly efficient primers, the NS5 region of hepatitis C virus (HCV) genome could be amplified from all of the 24 serum samples randomly obtained from Japanese patients with liver diseases. Subtype analysis on the basis of nucleotide sequence similarities of the amplified fragments revealed that 2 out of 24 Japanese patients (8.3%) were infected with the recently identified subtype HCV-3b, which had been thought to be rare in Japan.

Genomic and replicative hepatitis C virus RNA sequences and histologic activity in chronic hepatitis C

Hepatitis C virus (HCV) frequently leads to chronic hepatitis, cirrhosis, and hepatocellular carcinoma, but the mechanism of liver injury is unknown. To determine whether replication of HCV is related to liver damage, we studied 17 liver biopsy specimens (six anti-HCV-positive chronic persistent hepatitis specimens, seven anti-HCV-positive chronic active hepatitis specimens, and four anti-HCV-negative controls) by reverse transcription followed by double polymerase chain reaction for the 5' nontranslated regions of the genomic and replicative strands of HCV. The histologic activity index as well as lymphoid aggregates in portal tracts, bile duct damage, and fatty change were assessed semiquantitatively. There was a statistically significant correlation between the presence of HCV RNA sequences in liver tissue and anti-HCV antibody in serum (P < .005). No correlation was detected between the histologic activity index or any individual histologic parameters and the presence of genomic or replicative strands of HCV. These findings suggest that a direct viropathic effect is less important than other mechanisms, such as the host immune response, in the pathogenesis of hepatocyte and bile duct injury in chronic hepatitis.

New approaches to the treatment of chronic viral hepatitis B and C

Interferon treatment of hepatitis B and C virus (HBV, HCV) infections has been hampered by overall initial response rates of < 50%, a relapse rate that is > 50% for patients with chronic HCV, and rare responses in individuals with chronic HBV who are immunosuppressed or immunologically tolerant to the HBV. Because of these difficulties, the efficacy of other therapeutic agents is being vigorously explored. Among the immunomodulatory agents being evaluated, thymosin appears to be a promising new therapy for HBV. Results from an ongoing multicenter trial evaluating thymosin are expected next year. A variety of nucleoside analogues with antiviral activity against the HBV have also been identified. Several of the more active agents deserve further study in clinical trials. In chronic HCV infection, only interferon therapy has been extensively studied. Ribavirin alone may have some value, but its precise role in the treatment of chronic HCV will require additional testing. Interferon therapy for patients with chronic HBV or HCV infection represents an important first step in the treatment of these disorders. In the absence of an ideal antiviral agent, however, combinations of the available antiviral and immunomodulatory agents or synergistic combinations of antiviral agents need to be studied in order to achieve better therapeutic responses.

Variability of the E2/NS1 region of Swedish hepatitis C virus strains and its correlation to genotypes

Serum RNA was extracted from 5 Swedish patients infected with hepatitis C virus (HCV). The N-terminal part of the genomic region coding for the gp70 (E2/NS1), including the hypervariable domain of the E2 protein, was reverse transcribed and amplified by the polymerase chain reaction (PCR) using biotinylated primers. The amplicon was immobilized on magnetic polystyrene beads coated with streptavidine. Solid-state sequencing was carried out on the bound single-stranded DNA, after denaturation. The results of phylogenetic sequence analysis and calculated ratios of transition and transversion mutations showed that 4 of the strains clustered together with the USA prototype strains HCV-1 and HCV-H (genotype I), while 1 strain was close to the Japanese isolate HCV-J, and particularly to isolate HCV-BK (genotype II). Possible antigenic epitopes in the Swedish strains were mapped in the HVR region.

Rapid detection of hepatitis C virus RNA by direct capture from blood

A new diagnostic assay for hepatitis C virus RNA detection is described. HCV genomic RNA is captured onto streptavidin-coated magnetic beads by solution hybridization with biotinylated complementary oligonucleotides. The specificity of the capture assay is confirmed using different capture oligonucleotides as well as sera representing different types of HCV. Sensitivity was determined by testing serial dilutions of a HCV infected plasma. A panel of 50 sera was tested for anti-HCV by a Line Immunoassay and for HCV-RNA by both a conventional guanidinium extraction method and the new capture assay. The specificity of the capture assay was 95.8% and the sensitivity was 92.3% compared to the standard protocol. This method provides a rapid and simple alternative for HCV-RNA detection in blood samples.

CD3- and CD28-activating pathways in HCV infection

We investigated the proliferative response and IL-2 receptor (IL-2R) expression in peripheral blood mononuclear cells (PBMC) activated with anti-CD3 mAb alone or in combination with anti-CD28 mAb in a group of hepatitis C virus (HCV)-infected patients with detectable viremia demonstrated by "nested" PCR. PBMC from HCV patients and controls showed similar proliferative responses either to anti-CD3 mAb, 64.1, and/or to anti-CD28 mAb, 9.3. No differences were found in anti-CD3 or anti-CD3 plus anti-CD28-induced proliferative responses between patients who demonstrated circulating PBMC bearing HCV-RNA when compared to those with negative HCV-RNA PBMC. Moreover, flow cytometry studies confirmed that anti-CD3 alone or in combination with anti-CD28 were able to induce a significant increase of IL-2R expression in patients or controls PBMC. Both groups showed similar basal CD28 expression. These results indicate that both CD3- and CD28-activating pathways are preserved in HCV-infected patients with chronic active liver disease.

[Hepatitis C]

Hepatitis C virus (HCV), identified in 1989, is the main agent of Non-A, Non-B hepatitis. The number of HCV carriers in France is estimated between 500,000 and 2 millions. The main risk factors for HCV infection are blood products transfusion and i.v. drug abuse. Cirrhosis occurs in 30% of cases with a delay ranging from 10 to 30 years, and hepatocellular carcinoma in 2.5% of cases. Interferon is, for instance, the only effective therapy in patients with chronic hepatitis C; however, prolonged response (in terms of transaminase normalization) after stopping treatment occurs only in 20% of patients.

The impact of hepatitis C virus infection on renal allograft recipients

A second generation hepatitis C virus recombinant immunoblot assay (RIBA) was used to screen stored perioperative serum from 641 renal allograft recipients. One hundred and nine (17%) were anti-HCV positive at the time of transplant. RIBA positivity was found to be an independent predictor of post-transplant liver disease in a logistic regression model (P < 0.05). Moreover, RIBA positive patients were at greater risk for infectious events (P = 0.03) and rejection episodes (P = 0.002). The cumulative dose of antilymphoblast globulin administered as induction therapy was an independent predictor of post-transplant liver disease in a dose response relationship. Qualitative PCR showed that 74% of the perioperative RIBA positive patients had detectable HCV RNA in a current serum sample. Further, quantitative HCV RNA analysis with a competitive template PCR and HCV strain identification by restriction fragment length polymorphism demonstrated a large range of HCV RNA copies/ml of serum and three different HCV strains (BK, Hutch and HCV-1). Neither quantity of HCV RNA nor strain type correlated with abnormal transaminases post-transplant. As yet, there has not been an effect of anti-HCV status on actuarial patient and graft survival. This study suggests that anti-HCV is not a contraindication to renal transplantation; however, we would recommend that the pre-transplant evaluation of the anti-HCV positive patient include a liver biopsy to properly stage the disease. Close post-transplant follow-up is required in view of the increased risk for infection and rejection.

Second-generation anti-HCV screening in a Saudi Arabian donor population

The 2nd-generation anti-HCV test system was applied to a Saudi Arabian multi-ethnic donor population. When donors were stratified according to first-time donations versus repeat donations, the latter having been screened previously by a 1st-generation set of tests, it was found that in Saudi Arabian and Middle East nationals, the 2nd-generation tests (EIA and RIBA), identified close to double the number of anti-HCV-positive donors, compared to an earlier study using the 1st-generation tests. Part of this finding was due to a 38% higher rate of RIBA-confirmable repeat-positive EIA results. In groups of donors, previously screened by the 1st-generation system, some additional cases of anti-HCV reactivity were identified, most prominently in Middle East nationals. It is assumed that some of these represented recent seroconversions, while others were cases of serologic subtypes of HCV, not reacting in the 1st-generation tests. The current test system identifies 0.66% of Saudi-Arabian, and 2.87% of other Middle East donors as putative carriers of hepatitis C virus. The study lends support to the opinion that donors who return regularly over the years have a lower prevalence of disease markers, thereby being a safer source of blood than first-time donors.

Serum hepatitis C virus RNA levels in chronic hepatitis C--importance for outcome of interferon alfa-2b treatment

Sera from 39 out of 40 patients with chronic hepatitis C virus (HCV) infection who had been treated for 60 weeks with interferon alfa-2b proved initially HCV RNA positive by reversed transcriptase polymerase chain reaction (PCR). These patients were analysed for genotype and quantitatively for HCV RNA levels prior to treatment by using a competitive PCR method with colorimetric detection of the amplified products. HCV RNA levels were correlated to outcome of treatment, mode of acquisition, histology and HCV genotype. The median pretreatment HCV RNA level in sustained responders (n = 15) with eradication of the viremia and normalization of serum ALT levels lasting 24 weeks post treatment was significantly lower than that in the combined group of non-sustained responders (n = 9) and non-responders (n = 15), 2.52 x 10(5) vs 8.90 x 10(5) genome equivalents per ml serum, p < 0.0125, respectively. 10 out of 17 patients with HCV RNA levels lower than the median level (5.64 x 10(5) genome equivalents per ml serum) had a sustained response to interferon treatment versus only 5/22 with levels equal to or higher than the median level, p = 0.04. No significant pretreatment differences in median HCV RNA levels according to mode of acquisition, genotype, or liver histology prior to treatment were seen. It is concluded that a low pretreatment HCV RNA level seems to be indicative of a sustained response to interferon alfa-2b treatment, whereas a high level seems to be indicative of a non-sustained or non-response. In the individual patient, however, the levels varied widely irrespective of response category.

Detection of hepatitis C virus RNA by reverse-transcriptase and polymerase chain reaction: clinical applications of quantitative analysis

Polymerase chain reaction (PCR) applications to diagnostics allowed the detection of viral nucleic acids in expected and unexpected clinical circumstances. This has raised some scepticism on the practical usefulness of PCR in the routine laboratory and emphasized the need for quantitative analysis. We addressed this question detecting HCV-RNA by a single step RT-PCR in serum samples from 50 patients with chronic non-A, non-B hepatitis included in clinical trials for recombinant alpha-interferon therapy. We obtained at least 5 serum specimens from each patient (baseline, during and after therapy samples) during an 18-month mean follow-up (range 12-45 months). RT-PCR was performed on total RNA extracted from 100 microl serum aliquots using primers for the highly conserved 5'NCR of HCV-RNA and 35 amplification cycles. PCR products were analyzed by agarose gel electrophoresis and Southern blot hybridization against a P(32)-oligonucleotide probe. Sensitivity was evaluated in separate experiments on tenfold dilutions of a reference Chimp serum containing 10(6) CID(50)/ml. The overall sensitivity of our assay ranged between 10(2) and 10(3) genome Eq./ml. We establish a semiquantitative score system to evaluate viremia levels: 2 = HCV-RNA levels >10(4) genome Eq./ml; 1 = levels between 10(3) and 10(4) g.Eq./ml; 0 = levels less than 10(2) g.Eq/ml. The reproducibility of this scoring system was confirmed testing repeatedly in duplicate end-point dilutions of positive serum samples. A statistically significant relation was observed between elevated HCV-RNA and ALT values (83.8%, chi-square 159.963 P < 0.001). Response to IFN therapy was significantly better in patients with lower baseline HCV-RNA levels. A time relation was found between flare-ups of serum HCV-RNA levels and ALT elevations higher than 3 x normal values viremia elevations coincident or occurring about 1 month earlier than ALT elevations. This finding suggests that immuno pathogenesis might be responsible of HCV-induced liver damage as in chronic hepatitis B where identical relations were observed between viremia and ALT serum levels. In conclusion, single-step HCV-RNA RT-PCR can be a specific and reproducible semiquantitative assay and provides useful diagnostic informations for therapeutic decision making and monitoring of HCV-infected patients.

Serological responses to different genotypes of hepatitis C virus in France

The relationship between hepatitis C virus (HCV) genotypes and antibody status was studied in 104 chronic non-A, non-B hepatitis patients and asymptomatic HCV-infected blood donors. On the basis of amplification of the nonstructural protein 3 (NS3) coding region by PCR and hybridization with specific probes, 55 and 42 patients were identified as being infected with type I and type II, respectively, according to the classification by H. Okamoto, K. Kurai, S. Okada, K. Yamamoto, H. Lizuka, T. Tanaka, S. Fukuda, F. Tsudaand, and S. Mishiro (Virology 188:331-341, 1992). All samples were tested for antibodies to 5.1.1, C-100, C-33, and C-22 proteins by a second-generation recombinant immunoblot assay. Among 97 patients with known HCV genotypes, 31 of 42 patients infected with type II and 24 of 55 infected with type I had antibodies against all four antigens (P < 0.01). In the type II-infected group, more patients had detectable antibodies to 5.11, C-33, and C-22 proteins than in the type I group (P < 0.05). No difference was found in the serological response to C-100 between the two groups.

Quantitation and typing of serum hepatitis C virus RNA in patients with chronic hepatitis C treated with interferon-beta

We quantified serum hepatitis C virus RNA titers and determined hepatitis C virus subtypes in chronic hepatitis C patients treated with interferon-beta to investigate relationships among serum ALT response, serum hepatitis C virus titer and hepatitis C virus subtype. Of 146 chronic hepatitis C patients who received interferon-beta therapy, 24 patients with sustained serum ALT normalization (complete responders) and 26 patients without serum ALT normalization (nonresponders) were randomly selected. Detection, typing and quantitation of hepatitis C virus were performed by means of the "single-tube" polymerase chain reaction method. Of the 24 complete responders, 21 (87.5%) became negative for hepatitis C virus RNA, whereas 21 (80.8%) of the 26 nonresponders remained positive. Hepatitis C virus infections with types I, II, III, IV, II + III and III + IV occurred in 0 (0%), 22 (51.2%), 10 (23.3%), 1 (2.3%), 7 (16.5%) and 3 (7.9%) patients, respectively. The mean pretreatment hepatitis C virus RNA titer of complete responders (0.4 +/- 2.0 x 10(4) CID50/ml) was significantly lower than that of nonresponders (3.8 +/- 4.5 x 10(4) CID50/ml) (p < 0.01). Regardless of HCV subtype, patients with more than 10(4) CID50/ml of HCV did not show serum ALT normalization, whereas complete serum ALT response was seen in most cases with less than 10(2) CID50/ml HCV. These results show that mixed infections with different hepatitis C virus subtypes appear to be more common than previously reported and that the pretreatment serum level of hepatitis C virus RNA is a more important predictor of outcome of interferon therapy than is virus genotype.

Chronic hepatitis in haemophilia

Chronic hepatitis affects almost all haemophiliacs treated with non-virally inactivated clotting factor concentrates. The virus responsible is hepatitis C (HCV) and most patients have non-neutralising antibodies with circulating virus. Although the majority also have evidence of past infection with hepatitis B, less than 5% are chronic carriers of HBsAg. Chronic hepatitis C can be associated with severe and progressive liver disease but the development of complications is slow. Treatment with recombinant interferon alpha given subcutaneously normalises the liver function in 50% of patients, but 50% of responders relapse on stopping treatment. Liver transplantation is successful in patients with advanced liver disease and it offers the added advantage of phenotypic cure of the haemophilic state.

Prediction of the response of chronic hepatitis C to interferon alfa: a statistical analysis of pretreatment variables

Pretreatment variables that could predict the response of chronic hepatitis C to interferon alfa treatment have not been fully assessed. Eighteen baseline variables were evaluated in a series of 100 consecutive patients treated with a 12 month course of interferon alfa. For the purposes of this study, response was defined as the return to normal of aminotransferase activities before the third month of treatment. Seventy per cent of the patients responded to treatment. Six variables were associated with an increased likelihood of response assessed by univariate analysis. With stepwise multiple regression analysis assessment, however, only three variables remained independently predictive of response: low gamma glutamyltransferase (gamma GT) activities (p < 0.001), absence of obesity (p = 0.005), and absence of cirrhosis (p = 0.01). The response rate in patients with gamma GT activities < 0.66 mu kat/l (n = 55) was 78% and 60% in patients with values > 0.66 mu kat/l (n = 45) (p = 0.048). Response was attained in 75% of non-obese patients (n = 80), compared with only 50% of obese patients (n = 20) (p = 0.03). Finally, 80% of patients without cirrhosis (n = 76) responded, while among those with cirrhosis (n = 24) the response rate was only 37% (p < 0.001). All 23 patients without cirrhosis, <40 years old, and with gamma GT activities <0.66 mu kat/l responded to treatment, while only 28.5% of 14 patients with cirrhosis, >40 years old, and with gamma GT activities >0.66 mu kat/l responded to interferon alfa (p<0.001). Those findings may be useful when evaluating interferon alfa trials and it is suggested that this treatment should be applied early in the course of chronic hepatitis C.

Detection of viremia by a one step polymerase chain reaction method in hepatitis C virus infection

A simple, sensitive, and specific one step polymerase chain reaction (PCR) method for the detection of hepatitis C virus (HCV) RNA in infected patients' serum or plasma samples is described. We performed the one step PCR amplification in combination with the initial step of reverse transcription by using oligonucleotide primers derived from the conserved 5'-untranslated region (5'-UTR) of the HCV genome. By utilizing this strategy, there was no need for nested or second stage PCR amplification. The PCR products (cDNAs) were easily visualized by agarose gel electrophoresis and ethidium bromide staining. Furthermore, the PCR products were characterized by Southern blot hybridization and DNA sequencing. We then used the one step PCR amplification method to detect the presence of HCV RNA in several infected patients' samples with acute and chronic infections. There was a 100% concordance between the results of PCR and second generation recombinant immunoblot assay (RIBA II). In addition, this method was found to be useful in determining viremia in HCV infected patients with indeterminate RIBA II results. The 5'-UTR of the HCV genome, being the most conserved region among different viral isolates, could be amplified by PCR for the detection of HCV RNA, as shown here, as well as serving as a potential target for antiviral agents.

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes recognize epitopes in the core and envelope proteins of HCV

Hepatitis C virus (HCV) is a major cause of posttransfusion and community-acquired hepatitis, and a majority of individuals infected with this virus will subsequently develop chronic hepatitis. Characterization of the host immune response to this infection is an important first step that should facilitate the development of immunomodulatory agents and vaccines. Cellular immune responses, especially those mediated by cytotoxic T lymphocytes (CTL), are important in the control of many viral diseases. In this study, liver-infiltrating lymphocytes from persons with chronic HCV hepatitis were examined for evidence of HCV-specific CTL by using target cells infected with recombinant vaccinia viruses expressing the HCV core, E1, E2, and part of the NS2 proteins. Bulk expansion of liver-derived CD8+ lymphocytes resulted in the detection of HCV-specific CTL activity, whereas activity could not be found in CD8+ lymphocytes expanded from peripheral blood. Epitopes recognized by these CTL were defined by using CTL clones obtained by limiting dilution and target cells sensitized with synthetic HCV peptides. Four distinct HLA class I-restricted epitopes were identified, including two epitopes in the amino-terminal portion of the core protein. These studies provide evidence that the highly conserved core protein is a target for HCV-specific CTL and identify CTL epitopes within the more highly variable E2 envelope protein. Our studies also suggest that HCV-specific CTL are localized at the site of tissue injury in infected persons with chronic hepatitis. Identification of the epitopes recognized by HCV-specific CTL will facilitate exploration of their role in disease pathogenesis and may provide information useful in development of therapeutic interventions or vaccines.

Incidence and risk factors for hepatitis C seroconversion in hemodialysis: a prospective study. The UCL Collaborative Group

To delineate the incidence and risk factors for seroconversion (SC) for HCV, from May 1991 to November 1992 we followed all 401 patients (no i.v. drug abusers) dialyzed in 15 Belgian hemodialysis (HD) units, none of which isolates anti-HCV (+) patients. The sensitive ELISA II test was performed in the same laboratory for all patients. ELISA II (+) sera were considered truly positive if specific antibodies were detected by RIBA II against at least one HCV antigen. Blood transfusions given from 12 months prior to inclusion in the study, dialyzer reuse and frequency of dialysis monitor sterilization were recorded. In May 1991, prevalence of truly positive ELISA II tests averaged 13.5% (54/399). During the three consecutive six-month periods, ELISA II became truly positive in 3 of 305 (1%), 4 of 314 (1.3%) and 1 of 313 (0.3%) patients, respectively, which was an average yearly incidence of 1.7%. SC was preceded (1 to 6 months) in all cases by an unexplained, unprecedented increase in the alanine aminotransferase level. The mean monthly rate of transfusions was significantly higher (P < 0.001) in eight patients with SC (0.7 +/- 0.6 U) than in 393 patients without SC (0.1 +/- 0.01 U). However, three of eight patients with SC had not been transfused at all. SC was observed in only 3 of 13 units (1, 3 and 4 cases, respectively) dialyzing ELISA (+) patients. In the unit with three SC, patients were always assigned a fixed station: SC was observed only in patients dialyzed next to an ELISA II (+) patient (3 of 8 vs. 0 of 30, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus infection in anti-HIV positive and negative French homosexual men with chronic hepatitis: comparison of second- and third-generation anti-HCV testing

To determine the prevalence of hepatitis C virus (HCV) infection in homosexuals with chronic hepatitis, we tested for anti-HCV antibodies 113 (47 anti-HIV positive) French non-drug-addicted homosexual men admitted for chronic viral hepatitis. Anti-HCV were detected with second- and third-generation ELISAs (ELISA2 and ELISA3) and RIBAs (RIBA2 and RIBA3). Chronic hepatitis was related to non-A, non-B infection in four, to hepatitis D virus (HDV) infection in five and to hepatitis B virus (HBV) infection in 104 patients. Anti-HCV positivity was found in 50.4% and 12.4% of the 113 patients, with ELISA2 and ELISA3, respectively. Positivity with RIBA2 and RIBA3 was found in only six of the 57 ELISA2 positive patients (all six were ELISA3 positive). The high prevalence of positivity with ELISA2 not confirmed by RIBA2 or RIBA3 suggests false-positive results. ELISA2 positive results were more frequent with frozen serum samples than with fresh serum samples (62% vs 23.5%, p = 0.0003). However, even with fresh serum, ELISA2-positive RIBA-negative results remained frequent in anti-HIV positive patients. ELISA3 seems to give more specific results. We conclude that the prevalence of HCV infection, as assessed with RIBA, was 5.3% among French homosexual men with chronic hepatitis (3.8% after exclusion of transfused patients). This low prevalence suggests that homosexual transmission of HCV is relatively uncommon.

Analysis of discordant test results among five second-generation assays for anti-hepatitis C virus antibodies also tested by polymerase chain reaction-RNA assay and other laboratory and clinical tests for hepatitis

The diagnostic performances of five commercially available second-generation assays for anti-hepatitis C virus antibody, two enzyme-linked immunosorbent assays, one enzyme immunoassay, and two particle agglutination assays (passive hemagglutination assay and particle agglutination assay), were evaluated. Among 104 samples from healthy subjects and 300 consecutive samples from patient ordered for routine determinations of anti-hepatitis C virus antibody in serum, assay results showed variable degrees of discordance for 17 samples (4.2%). These 17 samples were further tested by an immunoblot assay, the polymerase chain reaction-RNA assay, and the hemagglutination inhibition assay. Four of the 17 samples were regarded as true positive, since all supplementary assays and clinical data indicated active hepatitis C virus infection. Another five samples were considered false positive because no confirmatory evidence was obtained from the laboratory analysis or clinical data. The remaining eight samples were negative for hepatitis C virus RNA, but the results of the other supplementary tests were indeterminate. Some of these samples with indeterminate results may have been from patients with subclinical cases of disease who spontaneously recovered from hepatitis with persistent anti-hepatitis C virus antibody in their sera.

Diagnosis and treatment of the major hepatotropic viruses

The hepatotropic viruses currently include hepatitis A, B, C, D, and E, and are associated with a spectrum of acute and chronic liver disease syndromes. The epidemiology and natural history of each are discussed, with emphasis on uncommon or newly recognized clinical presentations. The serodiagnosis of hepatitis A, B, and D is well established; the serodiagnosis of hepatitis C and E continues to evolve as serologic and virologic assays become refined. Hepatitis A and E only cause acute liver injury; current medical approaches therefore focus on vaccination strategies. Hepatitis B, C, and D can cause both acute and chronic liver injury. Sequelae of chronic liver disease, including portal hypertension and hepatocellular carcinoma, are not uncommon. Medical therapy of resulting chronic liver disease currently consists of interferon, though other anti-viral strategies are being explored. Advanced chronic liver disease due to hepatitis B, C, or D can be treated by orthotopic liver transplantation, but viral recurrence is near uniform and can be problematic. Further study of the hepatotropic viruses at the molecular biologic, epidemiologic, and clinical levels will continue to provide greater insight into the diagnosis and management of their associated clinical syndromes.

Demonstration of hepatitis C virus genome in saliva and urine of patients with type C hepatitis: usefulness of the single round polymerase chain reaction method for detection of the HCV genome

The possible transmission routes of hepatitis C virus (HCV) in patients without overt parenteral exposure (sporadic or community acquired form) were examined. Saliva and urine specimens obtained from type C hepatitis patients, whose sera were positive for the HCV genome, were examined by reverse transcription and polymerase chain reaction (RT-PCR). By analyzing the factors that influenced the detection of the HCV genome by PCR, we developed a single round method which enabled semiquantitative detection with higher sensitivity than that obtained with nested PCR. Single round PCR revealed that 34.8% (8 of 23) of saliva and 56.5% (13 of 23) of urine specimens from patients with type C hepatitis contained the HCV genome. The amounts of HCV genome in saliva and urine specimens correlated with those in serum. The relative amounts of HCV genome in serum, saliva, and urine from a chronic type C hepatitis patient were determined by comparing the reciprocal of the smallest volume of the specimens in which the PCR products were visualized in agarose gels (PCR units/ml), and the values were 1 x 10(5), 5 x 10(1), and 3 x 10(1) PCR units/ml for serum, saliva, and urine specimens, respectively.

The hepatitis C virus genome: a guide to its conserved sequences and candidate epitopes

A comprehensive analysis of reported hepatitis C virus genomic sequences comprising 151 partial or complete nucleotide sequences and 159 partial or complete amino acid sequences revealed an irregular composition of conserved and variable regions. There were but eight conserved nucleotide sequences, none outside the 5' noncoding and structural regions. A search among conserved amino acid sequences revealed 14 candidate B-cell epitopes, which were chosen mainly on the basis of their hydrophilicity profiles. Twenty five candidate T-cell epitopes were selected according to the criteria of absolute conservation of amino acid sequence, together with characteristic sequence motifs, amphipathic helical structure, or both. Conserved peptide sequences, with the characteristics of both B- and T-cell epitopes, were identified in the nonstructural 5 (NS5) region of the genome.

Hepatitis C virus NS3 protein polynucleotide-stimulated nucleoside triphosphatase and comparison with the related pestivirus and flavivirus enzymes

Sequence motifs within the nonstructural protein NS3 of members of the Flaviviridae family suggest that this protein possesses nucleoside triphosphatase (NTPase) and RNA helicase activity. The RNA-stimulated NTPase activity of this protein from prototypic members of the Pestivirus and Flavivirus genera has recently been established and enzymologically characterized. Here, we experimentally demonstrate that the NS3 protein from a member of the third genus of Flaviviridae, human hepatitis C virus (HCV), also possesses a polynucleotide-stimulated NTPase activity. Characterization of the purified HCV NTPase activity showed that it exhibited reaction condition optima with respect to pH, MgCl2, and salt identical to those of the representative pestivirus and flavivirus enzymes. However, each NTPase also possessed several unique properties when compared with one another. Notably, the profile of polynucleotide stimulation of the NTPase activity was distinct for the three enzymes. The HCV NTPase was the only one whose activity was significantly enhanced by a deoxyribopolynucleotide. Additional distinguishing features among the three enzymes relating to the kinetic properties of their NTPase activities are discussed. These studies provide a foundation for investigation of the putative RNA helicase activity of these proteins and for further study of the role of the NS3 proteins of members of the Flaviviridae in the replication cycle of these viruses.

Structural proteins of hepatitis C virus

Despite the lack of an in vitro replication system, genes coding for viral proteins of hepatitis C virus have been identified. The putative nucleocapsid (p22) and envelope (gp35 and gp58) proteins have been expressed in cells by different vectors under various foreign promoters. Detection of antibodies to these proteins in patient sera suggests that they are indeed synthesized during the course of viral replication.

Detection of hepatitis C virus genome in human serum by multi-targeted polymerase chain reaction

A multi-targeted "hemi-nested" PCR (M-PCR) assay in which the primer pairs derived from the 5' non-coding (5'NC) and the nonstructural protein 3 (NS3) regions of HCV genome were concurrently used for amplification in order to compare the sensitivity and specificity of polymerase chain reaction (PCR) with different primer pairs in detecting hepatitis C virus (HCV) genome. Sera from patients with virus-associated liver diseases were examined for the presence of HCV RNA by the M-PCR method following reverse transcription to cDNA. The amplified products derived from both the 5'NC and the NS3 regions were detected in 28 (70%) of the 40 HCV RNA-positive samples. However, 12 samples (30%) were devoid of the signal of NS3-derived product. Sensitivity tests using serial dilutions of HCV RNA revealed that the 5'NC-derived band was still detectable in the 10(5)-fold diluted sample by the M-PCR method, yet the NS3-derived band could hardly be detected in the 10(4)-fold diluted sample. Thus, as previously demonstrated by a single-targeted "nested" PCR assay, the present study using the M-PCR assay has clearly shown that the 5'NC-derived primers are more sensitive and specific than the NS3-derived primers in detecting HCV RNA.

High-performance liquid chromatography to assess the effect of serum storage conditions on the detection of hepatitis C virus by the polymerase chain reaction

The effect of various serum storage conditions on the detection of hepatitis C virus (HCV) by the polymerase chain reaction (PCR) was assessed. 50 microliters aliquots of serum from four HCV PCR positive patients were subjected, in triplicate, to: (a) storage at -20 degrees C for 1, 5, 10 days; (b) storage at room temperature (RT) for 1, 2, 7 days; (c) 1, 3, 5, and 10 successive freeze-thaw cycles; (d) incubation at 37 degrees C, and 56 degrees C for 1, 3, 24 h; and (e) storage in guanidium-thiocyanate extraction buffer at RT, and 4 degrees C for 1, 5, 10 days. PCR products were detected by agarose gel electrophoresis (AGE) and quantitatively by high-performance liquid chromatography (HPLC). Only storage in extraction buffer at RT for 5-10 days and incubation at 56 degrees C for 24 h appeared to result in a loss of > or = 50% of detectable HCV PCR product. Up to 10 successive freeze-thaw cycles, storage at -20 degrees C for up to 10 days or at RT for up to 7 days, storage in extraction buffer at RT for 1 day or at 4 degrees C for up to 10 days, and incubation at 37 degrees C for up to 24 h resulted in minimal PCR signal loss. HPLC was a reproducible method of detecting and quantitating HCV PCR products, and was more sensitive than AGE.

Genetic variability of German hepatitis C virus isolates

Heterogeneity of hepatitis C viral (HCV) genomes of several isolates from different countries has been reported, but there is little information on HCV isolates for the Federal Republic of Germany. Therefore, the nucleotide (nt) and deduced amino acid (aa) sequences of interesting parts of the viral genome derived from different human isolates in Germany were compared with each other and with the nt and predicted aa sequences of recently published isolates. HCV sequences were obtained by reverse transcription of viral RNA extracted from serum followed by polymerase chain reaction (PCR) amplification. Within the 5' nontranslated region we found only 3 single nucleotide exchanges among 2 of our isolates, and in comparison to sequences of Japanese isolates 2 to 3 exchanges, and to U.S. isolates 1 to 5 exchanges (homologies 98% to > 99%). Determination of a 249-bp core sequence from two German isolates exhibited 3% sequence divergence. The sequence of the core region (nt 342-911) showed a homology of about 88-91% on nt level and 96-97% on aa level as compared to U.S. isolates and other German isolates, and a homology of 95-96% (nt) and 96-98% (aa), respectively, to Japanese isolates. Less homologies were noticed for the E1 and E2/NS1 genes, especially in the N-terminal E2/NS1 hypervariable domain. Our isolates HD1 and HD2 showed nt sequence homologies of about 72-81% and aa homologies of 76-88% to U.S., German, and French isolates, and 89-91% (nt) and 88-96% (aa), respectively, to Japanese isolates. These results indicate that various German isolates are more closely related to Japanese isolates and differ from other European isolates as reported so far. Because of a nucleotide sequence heterogeneity of up to 10% among the tested isolates, we conclude that more than one closely related but distinct viral genotype of HCV exists in Germany. Furthermore, heterogeneous sequences of HCV can be detected in a single patient suggesting multiple infection with different genomic variants or, alternatively, a genetic drift forced by mutational events as a consequence of host immune selection.

One-step RNA polymerase chain reaction for detection of hepatitis C virus RNA

Although detection of hepatitis C virus RNA with polymerase chain reaction has become the standard for diagnosis, extensive application has been thwarted by polymerase chain reaction's labor intensiveness, risk of false-positive results through contamination and time required for individual assays. To minimize these limitations, we developed and validated a one-step hepatitis C virus RNA polymerase chain reaction assay. The one-step method was compared with traditional hepatitis C virus RNA polymerase chain reaction using primers from the highly conserved 5' untranslated region of the hepatitis C virus genome. Variables studied in the one-step method included the source and quantity of reverse transcriptase (RTase), the concentration of MgCl2 and the duration of reverse transcription and complementary DNA amplification cycles. Optimal conditions for the one-step method were obtained with 25 U of reverse transcriptase and 2 mmol/L MgCl2. The one-step method substantially reduced the time required for analysis. The sensitivity of the one-step method was comparable to that of traditional hepatitis C virus RNA polymerase chain reaction using serially diluted RNA extracted from the serum of a hepatitis C virus-infected patient. The specificity of the one-step method was confirmed on Southern-blot hybridization. The results exhibited 100% concordance with results of traditional hepatitis C virus RNA polymerase chain reaction in 50 serum samples, including those of positive and negative controls. In addition, 100% concordance was observed between the two methods' results when sera containing low levels of hepatitis C virus RNA were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Superinfection of heterologous hepatitis C virus in a patient with chronic type C hepatitis

A Taiwanese woman who had chronic infection of type II hepatitis C virus was superinfected by type III hepatitis C virus after blood transfusion. The subtypes of the hepatitis C virus were determined by direct sequencing of the envelope region of the viral genome in serial serum samples before and after transfusion. The original virus in the patient had a 95.6% homology to the Taiwanese isolate (a type II virus) by comparing nucleotide sequences of the envelope region. After transfusion, markedly elevated serum aminotransferase activities were noted and the virus sequenced showed only a 55.2% homology to the Taiwanese isolate but had a 88.9% homology to a Japanese isolate (a type III virus). After recovery from the acute episode, the newly introduced type III virus became undetectable and type II virus predominated again but with significant genetic variation in the follow-up samples as compared with the original type II virus. It was concluded that superinfection of hepatitis C virus indeed occurs in humans, and this should be taken into consideration in the pathogenesis of reactivation of chronic type C hepatitis.

Clinical significance of the antibody to the putative core protein of hepatitis C virus in patients with chronic liver disease

We evaluated the clinical significance of the antibody to hepatitis C core protein (anti-p22) analysing 147 sera from 99 patients; 45 of them had post-transfusion non A non B (NANB) hepatitis, 28 cryptogenic non A non B hepatitis, 12 chronic hepatitis B, 7 chronic hepatitis D, 6 other forms of liver disease (4 primary biliary cirrhosis, 2 autoimmune hepatitis) and 1 rheumatoid arthritis. All sera were tested by commercial 1st and 2nd-generation ELISAs and anti-p22 single antibody ELISA. We found a highly significant correspondence between anti-p22 and commercial assays (p = 0.0001). HCV-RNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR) in sera showing positive or negative concordant results and in all sera (24) that showed discordant results by anti-p22 and commercial ELISAs. HCV-RNA was found in 14 of 17 (82%) anti-p22 positive sera that were negative by commercial ELISAs, in 1 of 7 (14.3%) anti-p22 negative sera that were positive by commercial ELISAs (p = 0.001) and in all control sera from patients with positive concordant results. It was undetectable in 7 sera from patients with autoimmune diseases (negative by all ELISAs). We studied follow-up sera from 16 patients treated with interferon: 8 long-term responders (with persistently normal ALT levels for at least 24 months after discontinuation of therapy and histological remission) and 8 non-responders. Sera were also tested by a 4-antigen recombinant immunoblotting assay (RIBA II).(ABSTRACT TRUNCATED AT 250 WORDS)

Humoral immune response to hypervariable region 1 of the putative envelope glycoprotein (gp70) of hepatitis C virus

We recently found that alterations of amino acids in hypervariable region 1 (HVR1) of the putative envelope glycoprotein (gp70) of hepatitis C virus (HCV) occurred sequentially in the chronic phase of hepatitis at intervals of several months. This finding suggests that mutations in HVR1 are involved in the mechanism of persistent chronic HCV infection involving escape from the immunosurveillance system. To explore this possibility, we examined the humoral immune response to HVR1 with our assay system, in which immunoprecipitation was carried out with sera from patients by using an HVR1 (27-amino-acid) dihydrofolate reductase fusion protein synthesized by in vitro transcription and translation. Results showed that HVR1 contains a sequence-specific immunological epitope that induces the production of antibodies restricted to the specific viral isolate. Furthermore, analysis of the kinetics of the appearance of antibodies in two patients with chronic hepatitis, with whom successive alterations of amino acids of HVR1 have been observed, showed that the titers of anti-HVR1 antibodies usually reached maximal levels several months after the isolation of HCV having the specific sequence of HVR1. This observation suggests that anti-HVR1 antibodies are involved in the genetic drift of HVR1 (minor antigenic variation) by immunoselection. However, the coexistence of HVR1 as an antigen and its specific antibody was sometimes observed. The possibility that HVR1 acts as a neutralizing epitope is discussed.

Risk factors for hepatocellular carcinoma among patients with chronic liver disease

BACKGROUND AND METHODS

To detect potentially curable cases of hepatocellular carcinoma, outpatients with chronic hepatitis or compensated liver cirrhosis who were seen at the Center for Adult Diseases (Osaka, Japan) were examined periodically by means of ultrasonography and measurement of serum alpha-fetoprotein. Risk factors for hepatocellular carcinoma were identified with a Cox proportional-hazards model.

RESULTS

A total of 917 patients, 40 to 69 years old, were registered from May 1987 to March 1991. By the end of September 1991, liver cancer had developed in 54. The three-year cumulative risk of liver cancer was 12.5 percent for 240 patients with liver cirrhosis at enrollment and 3.8 percent for 677 patients with chronic hepatitis. Cox regression analysis showed that the risk of liver cancer was increased almost sevenfold in patients with hepatitis B surface antigen (rate ratio, 6.92; 95 percent confidence interval, 2.92 to 16.39) and fourfold in patients with hepatitis C antibody (rate ratio, 4.09; 95 percent confidence interval, 1.30 to 12.85). A high alpha-fetoprotein value at enrollment was also a risk marker for liver cancer.

CONCLUSIONS

Patients with hepatitis C virus infection have a greatly increased risk of liver cancer. Further studies are required to clarify the roles of other risk factors, including drinking and smoking habits.

Hypervariable 5'-terminus of hepatitis C virus E2/NS1 encodes antigenically distinct variants

Synthetic peptides representing sequences encoded at the 5'-terminus of E2/NS1 in hepatitis C virus (HCV) were constructed. Peptides synthesized based on the sequences of four distinct HCV isolates were used to develop enzyme immunoassays (EIAs) for detection of antibodies in chronic HCV patients and in HCV-infected plasma donors. HCV sequence-specific antibodies were detected among patients with chronic HCV from the United States and Italy at frequencies of 22.2% and 55.8%, respectively. Similarly, sequence-specific antibodies were detected in 54.6% of U.S. and 55.6% of Japanese commercial plasma donors who had previous evidence of HCV exposure. Our data support earlier findings of geographic variability among HCV variants. The region encoded by amino acids (aa) 380-436 was shown to contain at least one variant-specific and one conserved epitope. The data further indicate that a majority of patients chronically infected with HCV (58.1% U.S., 68.8% Italy) have antibodies directed to the 5'-terminus of the E2/NS1 gene product. We conclude that genotypic variability within the E2/NS1 gene of HCV results in antigenically distinct variants.

Hepatitis C RNA in liver of chronic hepatitis C patients before and after interferon alfa treatment

BACKGROUND

Successful treatment of chronic hepatitis C with interferon alfa is frequently followed by relapse. Because loss of hepatitis C viral RNA (HCV-RNA) in serum is not predictive of sustained response, the loss of HCV-RNA in liver as a predictor of sustained response was investigated.

METHODS

Twenty-one patients with chronic hepatitis C treated with recombinant interferon alpha had HCV-RNA sequences determined in frozen liver tissue before and after treatment and in serum at the end of treatment. Reverse double polymerase chain reaction was used to detect sequences to the 5' nontranslated region of the HCV genome using double nested primers.

RESULTS

HCV-RNA disappeared in the liver in 10 of 11 (91%) complete responders whereas it remained detectable in the liver or serum of 7 of 8 (87%) nonresponders. Five complete responders relapsed biochemically during 6 month's follow-up; 4 of these had no detectable HCV-RNA in liver at end of treatment.

CONCLUSIONS

Disappearance of HCV-RNA in liver correlates with initial clinical outcome, but as previously reported with serum HCV-RNA, this loss does not necessarily allow prediction of a sustained response.

The clinical significance of reactivity to individual epitopes of the hepatitis C viral genome

In order to analyze the clinical significance of the various HCV epitopes, we compared the results of different HCV specific assays with HCV-RNA, determined in serum by RT-PCR method using primers to the 5' untranslated region of HCV-RNA. Among 73 patients with chronic NANB liver disease, 93% were positive for C22-3, 96% for C33C, 81% for C100-3 and 91% for RT-PCR. Positivity rates for 537 healthy subjects were 1.7% for C100-3 and 2.9% for second generation anti-HCV. A total of 6 persons were positive for C22-3 but not C100-3; all were negative for HCV-RNA. In 11 of 30 patients treated with interferon and HCV-RNA became negative and remained so for more than 24 months. In these 11 sustained responders, C100-3 and C33C antibody declined progressively, but C22-3 antibody showed a little change after treatment by quantitative analysis. The discrepancy of changes to NS region and core region after interferon treatment is consistent with a different clinical significance of reactivities to these HCV epitopes. Thus negative reactivity to NS region but positive for core region among healthy subjects may indicate past infection with HCV. Presence of antibodies to NS epitopes is implicated in HCV replication, while core epitopes indicate both present and past HCV infection.

HCV RNA in patients with chronic hepatitis C treated with interferon-alpha

In order to assess the efficacy of interferon-alpha on hepatitis C viral RNA in patients with chronic hepatitis C, we analyzed the levels of HCV RNA in sera and liver tissues of 16 patients pre- and posttreatment using a semiquantitative polymerase chain reaction method. Fifteen of 16 patients were positive for anti-HCV antibodies by four-antigen recombinant immunoblot assay (4-RIBA). Only two patients demonstrated normalization of ALT in response to interferon; three patients showed a partial response. Only one patient from the partial responder group displayed a significant reduction of HCV RNA level posttreatment. In the nonresponder group, several patients, although their ALTs remained elevated, demonstrated significant decreases in HCV RNA levels in either serum or liver in response to interferon. Our data suggest that interferon treatment of chronic hepatitis C may not be effective in eradicating HCV infection and a reduction in ALT is infrequently associated with a decrease in HCV RNA level in either serum or liver. Cessation of treatment is frequently associated with the recrudescence of HCV replication and disease.