Distribution of plural HCV types in Japan

Role of viral and host factors in interferon based therapy of hepatitis C virus infection

The current standard of care (SOC) for hepatitis C virus (HCV) infection is the combination of pegylated interferon (PEG-IFN), Ribavirin and protease inhibitor for HCV genotype 1. Nevertheless, this treatment is successful only in 70-80% of the patients. In addition, the treatment is not economical and is of immense physical burden for the subject. It has been established now, that virus-host interactions play a significant role in determining treatment outcomes. Therefore identifying biological markers that may predict the treatment response and hence treatment outcome would be useful. Both IFN and Ribavirin mainly act by modulating the immune system of the patient. Therefore, the treatment response is influenced by genetic variations of the human as well as the HCV genome. The goal of this review article is to summarize the impact of recent scientific advances in this area regarding the understanding of human and HCV genetic variations and their effect on treatment outcomes. Google scholar and PubMed have been used for literature research. Among the host factors, the most prominent associations are polymorphisms within the region of the interleukin 28B (IL28B) gene, but variations in other cytokine genes have also been linked with the treatment outcome. Among the viral factors, HCV genotypes are noteworthy. Moreover, for sustained virological responses (SVR), variations in core, p7, non-structural 2 (NS2), NS3 and NS5A genes are also important. However, all considered single nucleotide polymorphisms (SNPs) of IL28B and viral genotypes are the most important predictors for interferon based therapy of HCV infection.

Hepatitis C Genotype Determination by Melting Curve Analysis with a Single Set of Fluorescence Resonance Energy Transfer Probes

Background: The genotype of hepatitis C virus (HCV) is a predictor of antiviral therapeutic response. We describe an approach for HCV genotype determination by real-time PCR and melting curve analysis.

Methods: After automated nucleic acid extraction, we used reverse transcription-PCR in a block cycler to amplify nucleotides 6–329 of the 5′-untranslated region of HCV. The product was further amplified by single-tube real-time seminested PCR in a LightCyclerTM instrument (Roche). The final product was analyzed by melting curves with the use of fluorescence resonance energy transfer (FRET) probes. The FRET sensor probe was directed at nucleotides 151–170 of type 1 HCV and was designed to distinguish types 1a/b, 2a/c, 2b, 3a, and 4, with melting temperatures (Tms) predicted to differ by 1 °C. Genotypes were compared in a blinded fashion with those of the INNO-LiPATM test (Bayer Diagnostics) on 111 serum samples.

Results: In preliminary experiments, the Mg2+ concentration was found to be critical in allowing clear separation of melting points, with the best separation at a Mg2+ concentration of 2 mmol/L. The results for 111 samples clustered at expected Tms for genotypes 1a/b (n = 78), 2a/c (n = 2), 2b (n = 11), 3a (n = 14), and 4 (n = 2). Of the 111 samples, results for 110 were concordant with the comparison method at the level of type 1, 2, 3, or 4. Subtyping results were discordant for two samples, both of type 2. For 108 samples concordant with INNO-LiPA at the genotype and subtype levels, the mean Tms were 64.1, 59.5, 54.2, 52.6, and 50.1 °C for types 1a/b, 2a/c, 4, 2b, and 3a, respectively, with SDs of 0.2, 0.3, 0.3, 0.2, and 0.3 °C. All 78 samples identified as type 1 were concordant with results of the comparison method.

Conclusions: Melting analysis with a single pair of FRET probes can rapidly provide information about HCV genotypes and identifies type 1 samples with high specificity.

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

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

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

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

Genome of human hepatitis C virus (HCV): gene organization, sequence diversity, and variation

Hepatitis C virus (HCV) is the major etiologic agent of non-A, non-B hepatitis. HCV infection frequently causes chronic hepatitis, which progresses to liver cirrhosis and hepatocellular carcinoma. Since the discovery of HCV in 1989, a large number of genetic analyses of HCV have been reported, and the viral genome structure has been elucidated. An enveloped virus, HCV belongs to the family Flaviviridae, whose genome consists of a positive-stranded RNA molecule of about 9.6 kilobases and encodes a large polyprotein precursor (about 3000 amino acids). This precursor protein is cleaved by the host and viral proteinase to generate at least 10 proteins: the core, envelope 1 (E1), E2, p7, nonstructural (NS) 2, NS3, NS4A, NS4B, NS5A, and NS5B. These HCV proteins not only function in viral replication but also affect a variety of cellular functions. HCV has been found to have remarkable genetic heterogeneity. To date, more than 30 HCV genotypes have been identified worldwide. Furthermore, HCV may show quasispecies distribution in an infected individual. These findings may have important implications in diagnosis, pathogenesis, treatment, and vaccine development. The hypervariable region 1 found within the envelope E2 protein was shown to be a major site for the genetic evolution of HCV after the onset of hepatitis, and might be involved in escape from the host immunesurveillance system.

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

Analysis of the cell tropism of HCV by using in vitro HCV-infected human lymphocytes and hepatocytes

BACKGROUND/METHODS

We recently established two hepatitis C virus (HCV) replication systems, using MT-2, a human T-cell leukemia virus type I-infected human T-cell line, and PH5CH, a non-neoplastic human hepatocyte line immortalized with simian virus 40 large T antigen. These HCV replication systems were used to assess the infective potencies of seven sera containing more than 10(6) HCV genomes per ml obtained from HCV-positive blood donors.

RESULTS

The results showed that these sera had different infectivities for MT-2 and PH5CH cells. One of the seven sera, 1B-1, was more infective for MT-2 cells than PH5CH cells, whereas all the sera except serum 1B-1 were more infective for PH5CH cells than for MT-2 cells. Intracellular HCV RNA could be detected at least 30 days after inoculation with three of the sera. These findings suggested that the infective potency of each serum depends on the type of target cells. To further investigate HCV replication in these cells, we examined the hypervariable region 1 (HVR1) populations of HCV recovered from both MT-2 and PH5CH cells at 8 days postinoculation. The results revealed that the shift to limited HVR1 populations from the quasi-species of HVR1 populations in both cells usually occurred within 8 days after virus inoculation. Furthermore, in two of four sera, the predominant HVR1 populations in MT-2 and PH5CH cells appeared to be different.

CONCLUSION

These results suggest that HCV exhibits cell tropism.

Circulating HCV-RNA, HCV genotype, and liver histology in asymptomatic individuals reactive for anti-HCV antibody and their follow-up study

The present study was aimed to clarify the virologic status, liver histologies, and the results of follow-up liver tests in symptom-free individuals with anti-HCV antibodies and normal liver tests. Forty-nine individuals with normal liver tests and positive second generation anti-HCV antibody assay were entered into this study. Cases with hepatitis C viremia were evaluated for HCV genotype, amount of circulating HCV-RNA, and liver histology and were followed-up for more than one year. Of the forty-nine individuals, 36 had hepatitis C viremia, indicated by polymerase chain reaction (PCR) assay. Liver histology was as follows: 3 had non-specific changes, 25 had chronic persistent hepatitis (CPH), and 8 had chronic active hepatitis (CAH). Twenty-four cases with CPH and CAH developed an elevated AST and/or ALT concentration (> 30 IU/l) between 12 and 32 months of follow-up. The amount of circulating HCV-RNA ranged from 10(2) to 10(7) copies/50 microliters serum. The distribution of HCV genotypes was nearly the same as that for symptomatic CAH. These data suggest that the histological examination and follow-up examination are very important for following symptom-free individuals with hepatitis C viremia because there are some candidates for interferon therapy among them. There are few individuals who will remain healthy among asymptomatic HCV carriers.

Comparison of hypervariable regions (HVR1 and HVR2) in positive- and negative-stranded hepatitis C virus RNA in cancerous and non-cancerous liver tissue, peripheral blood mononuclear cells and serum from a patient with hepatocellular carcinoma

Hepatitis C virus (HCV) infection is associated with a wide spectrum of liver diseases including cirrhosis and hepatocellular carcinoma (HCC). Although the biological relation between the virus and cirrhosis or HCC is unclear, such variable pathogenicity may be related to the genetic heterogeneity of HCV. Genetic variability of HCV was assessed by determining the nucleotide sequence corresponding to the hypervariable regions (HVR1 and HVR2) of the putative envelope protein (E2/NS1) in positive- and negative-stranded HCV RNA from the cancerous and surrounding non-cancerous liver tissue, peripheral blood mononuclear cells and serum of a patient with HCC. Nineteen distinct HVR1 amino acid sequences (deduced from the nucleotide sequences) were obtained from the patient and could be classified into 5 groups on the basis of the site and time of detection. Some viral isolates with the same HVR1 sequence were shown to replicate in both cancerous and non-cancerous liver tissue, whereas others replicated in HCC tissue only.

Phylogenetic tree-based epidemiological analysis of hepatitis C virus transmission in a region of Japan with a high prevalence of infection

Local clustering of hepatitis C virus (HCV) infection has been demonstrated in various regions in Japan. HCV genotypes have now been compared between infected individuals from districts of Saga prefecture with either a high (H district) or low (L district) prevalence of HCV-seropositivity. The prevalence of HCV genotype 1b was significantly higher (P < 0.001) in the H district (45/50; 90%) than in the L district (19/36; 52.8%). A phylogenetic tree was constructed based on the genomic sequences of viral isolates from 20 patients infected with genotype 1b in the H district. Almost all these HCV strains clustered in the same regions of the tree. With regard to risk factors for HCV transmission, the percentage of patients with a history of surgery was significantly higher in the H district than in the L district (58 versus 33.3%; P < 0.05). Of 20 patients infected with similar strains of HCV in the H district, 16 (80%) had at least one parenteral risk factor associated with medical care. These results indicate an increased transmission of similar strains of HCV in the H district as a result of nosocomial infection.

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

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

Hepatitis C genotypes: current trends and future implications

OBJECTIVE

To review the geographic distribution and current understanding of hepatitis C virus (HCV) genotypes in regard to liver disease activity and response to treatment.

MATERIAL AND METHODS

We review the relevant medical literature and discuss our recent findings relative to chronic HCV infection and the importance of HCV genotypes.

RESULTS

HCV genotypes 1a and 1b are the most commonly found genotypes in patients with chronic HCV in the United States. Infection with HCV genotype 1b may be associated with more severe liver disease and may have a higher risk for the development of hepatocellular carcinoma. HCV genotype 2b seemed to be the most sensitive and HCV genotype 1b was the least sensitive to interferon therapy.

CONCLUSION

The identification of the infectious HCV genotype may be beneficial in clinical settings and may assist in the selection of patients who would benefit from interferon treatment.

Virology of hepatitis C virus

Hepatitis C virus (HCV) has been identified as the main causative agent of posttransfusion non-A, non-B hepatitis. Through recently developed diagnostic assays, routine serologic screening of blood donors has prevented most cases of posttransfusion hepatitis. The purpose of this paper is to comprehensively review current information regarding the virology of HCV. Recent findings on the genome organization, its relationship to other viruses, the replication of HCV ribonucleic acid, HCV translation, and HCV polyprotein expression and processing are discussed. Also reviewed are virus assembly and release, the variability of HCV and its classification into genotypes, the geographic distribution of HCV genotypes, and the biologic differences between HCV genotypes. The assays used in HCV genotyping are discussed in terms of reliability and consistency of results, and the molecular epidemiology of HCV infection is reviewed. These approaches to HCV epidemiology will prove valuable in documenting the spread of HCV in different risk groups, evaluating alternative (nonparenteral) routes of transmission, and in understanding more about the origins and evolution of HCV.

Genotype distribution and comparison of the putative envelope region of hepatitis C virus from Korean patients

Comparative nucleotide sequence studies of the genomes of hepatitis C virus (HCV) revealed that there are at least 6 different genotypes of HCV. The prevalence of HCV genotypes among the patients with liver diseases in Korea was investigated using the polymerase chain reaction (PCR) for the NS5 region. In the 75 HCV RNA positive samples, two genotypes, type 1b and type 2a, were the major causative agents which accounted for 60% and 33% of infections respectively, while 7% could not be assigned a genotype by the methods used. The nucleotide sequences of cDNAs encoding the putative envelope proteins from 10 type 1b and 5 type 2a genotype samples were analyzed. Approximately 31-42% of the nucleotide sequences of type 1b samples examined differed from those of different genotypes. In the case of type 2a samples, 36-42% of the nucleotide sequences differed from those of different genotypes. The diversities of the amino acid sequences were the same or greater than those of the nucleotide sequences. Two hypervariable regions (HVR1 and HVR2) were recognized in both HCV genomes of genotypes 1b and 2a. However, the sequence divergence within the HVR2 region of genotype 2a was less than that of genotype 1b.

Predictive factors for beneficial response to interferon-alfa therapy in chronic hepatitis C

OBJECTIVES

Interferon is the only established treatment for chronic hepatitis C but the host-dependent or virus-related factors affecting the response rate to interferon therapy are not yet clear. The purpose of this study was to investigate the factors predictive of response to interferon-alfa therapy in chronic hepatitis C.

METHODS

Twenty-five consecutive patients with chronic hepatitis C were randomized to three regimens of interferon-alfa: group A (n = 7, 3 MU every day for 3 months), group B (n = 8, 3 MU every other day for 3 months) and group C (n = 10, 3 MU every other day for 6 months). We quantified serum HC RNA levels by competitive reverse transcription-polymerase chain reaction (RT-PCR) and performed HCV genotyping using type-specific primers deduced form the NS5 region of the HCV genome. We also attempted to identify which demographic, biochemical and histologic factors in addition to virus-related factors would significantly predict beneficial response to interferon by multivariate analysis.

RESULTS

Sustained responders were 8 (36.4%), nonsustained responders were 2 (9.1%) and nonresponders were 12 (54.5%) of 22 patients who had received complete therapy. The initial HCV RNA level (logarithmic transformed copy numbers per ml of serum) in sustained responders (5.75 +/- 0.39) was significantly lower than that of nonsustained responders (6.80 +/- 0.71) and nonresponders (6.70 +/- 0.52) (p < 0.05). In multivariate multiple logistic regression analysis, the serum HCV RNA level before therapy was only the independent predictor of a sustained response to interferon-alfa therapy (p = 0.001).

CONCLUSIONS

Serum HCV RNA level before therapy was the most useful predictor of a sustained response to interferon-alfa therapy for chronic hepatitis C.

Epidemiologic survey and genetic analysis of endemic hepatitis C virus infection in a Japanese town with a high prevalence of hepatitis B virus carriers

Mass screening for hepatitis C virus antibody was carried out in 875 inhabitants (313 men and 562 women) of a town in Japan with a high rate of hepatitis B virus infection. The overall rate of positivity for anti-HCV was 8.8% (6.4% in men and 10.1% in women). The rate of positivity for hepatitis B virus surface antigen was 11.2%. Five subjects (0.6%) were positive for both markers. HCV-RNA was detected in 65 (88.4%) of 77 individuals who were positive for anti-HCV and in 1 (1.5%) of 60 individuals negative for anti-HCV. The genotype of the HCV genome was determined by PCR analysis using type-specific primers in 60 individuals. HCV type 1b was detected in 51 subjects (85%), type 2a in 3 subjects (5%), and type 2b in 6 subjects (10%). None of the individuals was infected with more than one genotype. The nucleotide sequences of the partial nonstructural 5 region of HCV type 1b genotype obtained from 6 individuals showed at least 92.0% homology in the nucleotide sequence, and 94.8% homology in the amino acid sequence. Homology among these clones was greater than their homology with previously described type 1b sequences. The findings suggest that there was a specific local origin of HCV infection, although it was not possible to identify any single source of HCV infection. The results also indicate that presence of asymptomatic HCV carriers.

Incidence of hepatocellular carcinoma in chronic hepatitis B and C: a prospective study of 251 patients

The incidence of hepatocellular carcinoma (HCC) was prospectively studied in 251 chronic hepatitis patients, and was compared between the 127 cases of hepatitis B and 124 cases of hepatitis C. All patients were diagnosed by needle biopsy on entering the study, and the cases consisted of chronic persistent hepatitis (CPH), chronic active hepatitis (CAH)2a, and CAH2b (cirrhosis was not included). Of the cases of chronic hepatitis B, 5 cases of HCC (3.9%) were detected; among the chronic hepatitis C cases, 13 cases (10.4%) were detected. Thus, although the mean follow-up periods were in the same range, the incidence of hepatocellular carcinoma was 2.7 times higher in hepatitis C than in hepatitis B (chi 2 = 3.116, P < .05). Using the Kaplan-Meier method, the incidence of HCC was significantly higher in chronic hepatitis C (P = .0194, generalized Wilcoxon test). In hepatitis C, the incubation period until HCC was detected was shorter when the liver disease was more advanced. Such a tendency was not observed in hepatitis B. In the 13 cases of HCC occurring in chronic hepatitis C, noncirrhotic liver was seen in only 1 case (7.7%), whereas 2 of the 5 cases of HCC (40%) in chronic hepatitis B were noncirrhotic. The prevalence of hepatitis C virus (HCV) genotypes II and III was the same in the total followed cases and HCC cases.

A retrospective study of hepatitis C virus carriers in a local endemic town in Japan. A possible presence of asymptomatic carrier

Chronic hepatitis, cirrhosis, and hepatocellular carcinoma are the accepted sequelae of chronic hepatitis C virus (HCV) infection. However, the real natural history of HCV infection is not still well understood. To approach this problem, we investigated 91 individuals positive for antibodies against HCV (anti-HCV), who have received annual liver function examination in a local town known to have had high carrier rates of hepatitis B virus (HBV) and HCV. Among the 91 anti-HCV-positive individuals, 63 had undertaken the annual examination more than five times in the past 14 years. We analyzed retrospectively the past liver function test results of these 63 subjects and evaluated their present virological status by determining HCV genotypes and estimating quantity of HCV RNA in the sera. Among the 63 subjects, 50 (79.4%) had HCV RNA in the serum and 40 (80%) of the 50 subjects with HCV RNA had abnormal alanine aminotransferase or aspartate aminotransferase level more than once in their records. However, the other 10 (20%) had no abnormal levels during the period examined. Six of 50 (12%) had ultrasonographic findings suggestive of cirrhosis. Thus, HCV-infected individuals in this area did not seem to have progressive liver diseases. Considering the advanced ages of the individuals examined (mean 64 years old), we may have observed a stage in the natural history of HCV infection in which viremia persists in most individuals and the tendency to progress to serious chronic liver disease is mild.

Expression and processing of putative nonstructural proteins of hepatitis C virus in insect cells using baculovirus vector

Processing of the putative nonstructural (NS) proteins, p70(NS3), p4(NS4A), p27(NS4B), p58/56(NS5A), and p66(NS5B), of Japanese type hepatitis C virus (HCV) in insect cells was analyzed by using a baculovirus expression system. Products processed by the HCV serine proteinase (Cpro-2) were essentially identical to those found in mammalian cultured cells transiently producing the NS region of the HCV precursor polyprotein. A series of internal and carboxy (C)-terminal deletion experiments coupled with epitope scanning analysis showed that efficient cleavage at the Cpro-2-dependent processing sites, except at the p4(NS4A)/p27(NS4B) site, is not significantly influenced by those mutations. Efficient cleavage at p4(NS4A)/p27(NS4B) required about 40% of the NS5A N-terminal region. Estimation of the processing sites by determination of the N-terminal amino acid sequences of the processed products revealed that all the Cpro-2-dependent cleavages occurred at essentially identical sites to those reported for another HCV genotype, suggesting that Cpro-2 is a possible target for the development of a strain-independent anti-HCV agent.

Prevalence of HCV genotype among patients with chronic liver diseases in the Tokyo metropolitan area

We examined 613 Toranomon Hospital patients with HCV RNA-positive chronic liver disease to elucidate the viral genotype in the Tokyo metropolitan area. An epidemiological and clinical study was conducted in the 565 patients whose HCV genotype could be determined. The HCV genotypes found were type II, in 414 patients (67.5%); type III, in 103 (16.8%); type IV, in 37 (6.0%); type V, in 4 (0.7%); mixed genotype II and III, in 5 (0.8%); and mixed genotype II and IV, in 2 (0.3%). The HCV genotype could not be determined in 48 patients. Type II was most prevalent. The HCV genotype I was not found at all. There were no significant differences between genotypes in relation to sex, age, history of blood transfusion, or the progression of the disease. It was uncommon to find a history of blood transfusion in the patients with mixed genotypes; however, a high incidence of hepatic disorders was noted among the family members of these patients. Ninety-two percent of the patients with HCV genotype II tested positive for C100-3, while 70.9% of those with type III, and 43.2% of those with type IV tested positive for this antibody. HCV genotype II was most prevalent, and the positivity rate for anti C100-3 in patients with this HCV genotype was significantly higher (P < 0.00001) than that in patients with the other genotypes.

Effects of interferon beta on non-A, non-B acute hepatitis: a prospective, randomized, controlled-dose study. Japan Acute Hepatitis Cooperative Study Group

BACKGROUND/AIMS

Non-A, non-B acute hepatitis progresses to a higher incidence of chronicity and hepatocellular carcinoma. To avoid the development of chronic liver disease, resolution of acute hepatitis C might be most effective. The aim was to establish the effect of interferon in disturbing progression to chronicity and to determine the most appropriate treatment protocol.

METHODS

Ninety-seven acute non-A, non-B hepatitis cases were randomly assigned to six different protocols and treated with 8.4-336 MU of interferon; 90 cases were finally completely analyzed. Titers of hepatitis C virus (HCV) RNA and HCV genotypes were determined.

RESULTS

Seventy-four cases were positive for second-generation anti-HCV. Of these, 65 (89%) were positive for HCV RNA. In these 65 cases, the resolution rate was 32%, and this rate was dependent on the total treatment dosage. Only the group treated with 336 MU showed a high (83%; 10/12) resolution rate; the other five groups had 0%-38% resolution.

CONCLUSIONS

Interferon treatment for acute hepatitis C could be regarded as a "vaccinelike" therapy by preventing the development of the virus carrier state.

Analysis of hepatitis C virus isolates among healthy blood donors and drug addicts in Chiang Mai, Thailand

Hepatitis C virus (HCV) isolates obtained from 25 anti-HCV antibody-positive healthy blood donors and 29 drug addicts in Chiang Mai, Thailand, were analyzed. HCV RNA was detected in 23 blood donor samples (92%) and 24 drug addict blood samples (83%) by PCR for a portion of the NS5 region. Subtype analysis revealed that HCV type 3a (HCV-3a) was the prevailing subtype (30%), which was followed in prevalence by HCV-1a (21%), -1b (13%), -3b (13%), and -6a (2%). Six (13%) of the 47 isolates showed low sequence similarities with known types and subtypes. The sequence variants could be grouped into four branches in a molecular evolutionary phylogenetic tree.

Genetic drift in hypervariable region 1 of the viral genome in persistent hepatitis C virus infection

The hypervariable region 1 (HVR1) of the putative second envelope glycoprotein (gp70) of hepatitis C virus (HCV) contains a sequence-specific immunological B-cell epitope that induces the production of antibodies restricted to the specific viral isolate, and anti-HVR1 antibodies are involved in the genetic drift of HVR1 driven by immunoselection (N. Kato, H. Sekiya, Y. Ootsuyama, T. Nakazawa, M. Hijikata, S. Ohkoshi, and K. Shimotohno, J. Virol. 67:3923-3930, 1993). We further investigated the sequence variability of the HCV genomic region that entirely encodes the envelope proteins (gp35 and gp70); these sequences were derived from virus isolated during the acute and chronic phases of hepatitis in one patient, and we found that HVR1 was a major site for genetic mutations in HCV after the onset of hepatitis. We carried out epitope-mapping experiments using the HVR1 sequence derived from the acute phase of hepatitis and identified two overlapping epitopes which are each composed of 11 amino acids (positions 394 to 404 and 397 to 407). The presence of two epitopes within HVR1 suggested that epitope shift happened during the course of hepatitis. Four of six amino acid substitutions detected in HVR1 were located within the two epitopes. We further examined the reactivities of anti-HVR1 antibodies to the substituted amino acid sequences within the two epitopes. HVR1 variants in both epitopes within the HVR1 escaped from anti-HVR1 antibodies that were preexisting in the patient's serum.

Genetic alterations of the putative envelope proteins encoding region of the hepatitis C virus in the progression to relapsed phase from acute hepatitis: humoral immune response to hypervariable region 1

Hypervariable region I (HVRI) of the putative second envelope glycoprotein (gp70) of hepatitis C virus (HCV) undergoes sequential alterations at intervals of several months during the chronic phase of hepatitis. To evaluate the implications of sequence variability in HVRI of HCV, we investigated the sequence variability of the whole envelope-protein(gp35 and gp70)-coding regions of HCV genome derived from patient M in acute and relapsed phases (8-month interval) of hepatitis. From this analysis, we found that a Leu (position 405) in HVRI substituted to Pro, and that 4 additional substitutions could be detected in gp70 during the relapsed phase. Sequence-specific antibody against HVRI derived from patient M was first detected in the serum at 8 months after the onset of hepatitis, but no other specific antibodies against peptides containing amino-acid position(s) substituted in regions other than HVRI could be detected. Epitope mapping using the sequence of HVRI derived from the acute phase of hepatitis was also performed, and a B-cell epitope (positions 397 to 407) of 11 amino acids was identified. However, the Pro variant at position 405 did not display an escape pattern from the antibody produced at 8 months after the onset. In addition, we demonstrated the existence of important amino-acid residue positions which are recognized by the anti-HVRI antibody produced in patient M using introduction point mutations within HVRI.

Characterization of the 5' noncoding and structural region of the hepatitis C virus genome from patients with non-A, non-B hepatitis responding differently to interferon treatment

We examined 14 patients with hepatitis C caused by infection with the hepatitis C virus-II genotype to understand differences in responsiveness to interferon. The patients were classified into two groups according to their response to interferon: eight responding and six non-responding patients. The 5' noncoding and structural regions of the hepatitis C virus-II genome from each patient specimen were amplified by reverse transcription followed by the polymerase chain reaction. The nucleotide sequences of these amplified DNAs were then determined. By comparing the nucleotide sequences and the deduced amino acid sequences of samples from both groups, no group-specific sequence was observed in the analyzed regions despite the presence of considerable sequence diversity. However, additional cysteine residues were observed in half the responding group. The degree of micro-heterogeneity in hypervariable region 1 of the hepatitis C virus in relation to the sensitivity to interferon treatment was also examined; however, no significant correlation was observed. In addition, frequent alterations in the amino acid sequences were observed in hypervariable region 1 during the course of interferon treatment.

Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey

The frequency of infection with the six classified major genotypes of hepatitis C virus (HCV) was investigated in 447 infected volunteer blood donors from the following nine countries: Scotland, Finland, The Netherlands, Hungary, Australia, Egypt, Japan, Hong Kong, and Taiwan. Viral sequences in plasma from blood donors infected with HCV were amplified in the 5'-noncoding region and were typed by restriction fragment length polymorphism analysis. Electrophoresis of DNA fragments produced by cleavage with HaeIII-RsaI and ScrFI-HinfI allowed HCV types 1 (or 5), 2, 3, 4, and 6 to be identified. Further analysis with MvaI-HinfI allowed sequences of the type 5 genotype to be distinguished from sequences of the type 1 genotype. Types 1, 2, and 3 accounted for almost all infections in donors from Scotland, Finland, The Netherlands, and Australia. Types 2 and 3 were not found in the eastern European country (Hungary), where all but one of the donors were infected with type 1. Donors from Japan and Taiwan were infected only with type 1 or 2, while types 1, 2, and 6 were found in those from Hong Kong. HCV infection among Egyptians was almost always by type 4. Donors infected with HCV type 1 showed broad serological reactivity with all four antigens of the second generation Chiron RIBA-2 assay (Chiron Corporation, Emeryville, Calif.), while infection with divergent HCV genotypes elicited antibodies mainly reactive to c22-3 and c33c. Reactivities with antibodies 5-1-1 and c100-3 were infrequent and were generally weak, irrespective of the geographical origin of the donor. Because the envelope region of HCV is even more variable than the NS-4 region, it is likely that vaccines based on these proteins need to be multivalent and perhaps specifically adapted for different geographical regions.

Hepatitis C viral markers in patients who received blood that was positive for hepatitis C virus core antibody, with genetic evidence of hepatitis C virus transmission

BACKGROUND

Despite the use of the anti-c100-3 assay for blood donor screening, posttransfusion non-A,non-B hepatitis still occurred. A more sensitive assay should be developed to prevent this.

STUDY DESIGN AND METHODS

Stored serum specimens from 2020 healthy blood donors who were negative for c100-3 antibody to hepatitis C virus (HCV) were retrospectively screened for the presence of antibodies against a core protein of HCV using an enzyme-linked immunosorbent assay and Western blot analysis as part of a study on posttransfusion non-A,non-B hepatitis.

RESULTS

Eight (0.4%) of the 2020 donors were positive for HCV core antibody. Posttransfusion non-A,non-B hepatitis occurred in 5 of five patients known to have received blood that was positive for HCV core antibody and 1 of 141 patients transfused with blood that was negative for HCV core antibody. The total incidence of posttransfusion non-A,non-B hepatitis was 4.1 percent (6/146). The nucleotide sequence of the nonstructural 5 region of the HCV genome obtained from two donors and corresponding recipients was also analyzed. The HCV genome sequences were identical for one donor-recipient pair, and there was 99.4-percent homology for a second pair.

CONCLUSION

Anti-core-positive blood proved to be highly infectious for HCV, and this validated the use of the second-generation anti-HCV assay for blood donor screening.

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.

Genetic alteration of the hepatitis C virus hypervariable region obtained from an asymptomatic carrier

Hepatitis C virus (HCV) genome shows extensive sequence diversity at 2 hypervariable regions (HVR1 and HVR2) of the putative envelope glycoprotein (gp70). We recently reported that the amino-acid sequence of HVR1, but not of HVR2, underwent a striking mutation or mutated sequentially over a period of several months in patients with chronic hepatitis (CH). Here, we examined whether these genetic alterations in HVR1 occurred in an asymptomatic HCV carrier. The level of HCV RNA in serum was almost the same throughout the 4 time points sampled over 16 months. However, we found that the amino-acid sequence of the HCV HVR1 from this asymptomatic carrier altered with time, as seen in patients with CH. Alterations of amino acids in the HVR1 were correlated with persistent HCV infection rather than with clinical symptoms. Sequence heterogeneity of HVR1 was not correlated with alanine aminotransferase (ALT) values or liver histological findings. The necessity of clinical follow-up of HCV asymptomatic carriers is discussed.

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.

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.

Molecular typing of hepatitis C virus genome from sera and liver tissues of patients with anti-HCV positive chronic liver disease

The authors investigated the distribution of HCV genotypes in patients with various chronic liver diseases in Korea. Study population was 70 individuals, positive for second generation anti-HCV EIA, consisting of 37 cases with sporadic non-A, non-B (NANB) chronic hepatitis (CH), 12 NANB hepatocellular carcinoma, 16 post-transfusion NANB hepatitis, 4 non-B blood donors and 1 healthy family member of a patient with sporadic CH. Molecular typing was performed by RT-nested PCR with type-specific primer sets deduced from the NS-5 region of HCV. The prevalence of type II was 75.0% and type III was 25.0% in sera. In liver tissues, type II HCV was shown in 63.0%, type III HCV in 3.7% and co-infections with type II and III HCV were observed in 18.5% of 27 samples biopsied. In the sera of patients with chronic hepatitis, typing results were relatively well correlated with those in tissues (75%), but type III could not be observed. Among 12 HCC patients, type III HCV appeared only in tissues, not in sera. These results suggest that type II HCV may be the major HCV type in Korea, and co-infections with type II and-III HCV may not be rare in chronic liver diseases with HCV.

Characterization of hypervariable regions in the putative envelope protein of hepatitis C virus

We previously identified two hypervariable regions [HVR1 (27 amino acids) and HVR2 (7 amino acids)] in the putative envelope glycoprotein (gp70) by comparison of the amino acid sequences of many isolates of the HCV-II genotype. To understand the functional features of these HVRs, using the polymerase chain reaction we analyzed the rate of actual sequence variability in the region including HVR1 and HVR2 of HCV isolated successively at intervals of several months from two patients with chronic C-type hepatitis. In both patients, the amino acid sequence of HVR1, but not HVR2, was found to change dramatically during the observation period (about one amino acid per month). However, no alteration of the amino acid sequence of HVR1 of HCV was observed in a patient in the acute phase of chronic hepatitis. Restriction digestion analysis of sequence diversity showed that a HCV genome with a newly introduced mutation in HVR1 often became the predominant population at the next time of examination. Alterations of amino acids in HVR1 occurred sequentially in the two patients in the chronic phase. These findings suggest that mutations in HVR1 are involved in the mechanism of persistent chronic HCV infection.

A new type of hepatitis C virus in patients in Thailand

Partial nucleotide sequences in the tentative NS5 region of the hepatitis C viral genome obtained from patients with chronic hepatitis in Thailand were analyzed by reverse transcription followed by the polymerase chain reaction. Of ten samples studied, four showed low homologies to any known type of HCV: the homologies of the nucleotide sequences of these clones with HCV-J, -US, -K2a and -K2b were 66.5-69.1%, 66.5-68.2%, 61.2-64.1% and 64.4-66.2%, respectively, and the homologies of their deduced amino acids sequences were 71.7-75.2%, 71.7-75.2%, 69.0-72.6% and 69.9-73.5%, respectively. These four clones were classified a new distinct type of HCV, named HCV-T. Moreover, the nucleotide and amino acid sequence homologies of the four HCV-T clones showed that the HCV-T type could be classified into two genotypes, HCV-Ta and HCV-Tb.