Isolation of a complementary DNA fragment of hepatitis C virus in Taiwan revealed significant sequence variations compared with other isolates

Cloning and characterization of the extreme 5'-terminal sequences of the RNA genomes of GB virus C/hepatitis G virus

The extreme 5'-terminal sequences of the GB virus C/hepatitis G virus (GBV-C/HGV), containing elements essential for regulation of viral gene expression and replication, have not been determined. By using a RNA-ligase-mediated RACE (rapid amplification of the cDNA ends) procedure, we have cloned the extreme 5'-terminal sequences of the viral genome from the serum of three Taiwanese patients. Sequence analysis of the 5' noncoding region in alignment with one West African and two American isolates showed that (i) a consensus 5'-end sequence was cloned; (ii) about 97% of sequences were homologous among the three Taiwan isolates and also between the two American isolates, whereas about 90% of sequences were homologous among the isolates from the three different geographic areas; (iii) the sequence heterogeneity related to geographic separation is confined mainly to three domains; and (iv) a potential hairpin structure, resembling the hairpin structure found in the 5' end of hepatitis C virus genome, was detected in the 5' end of the noncoding region. Our data support the hypotheses that (i) the extreme 5' end of the hepatitis GBV-C/HGV viral genome has been cloned, (ii) there are different genotypes correlated with geographic separation, and (iii) the viral translation and replication mechanisms may be similar to that of hepatitis C virus and pestiviruses. Our data have not only shed light on the viral replication mechanism but also offer information for selection of optimal primer sequences for the detection and genotyping of the hepatitis GBV-C/HGV virus by PCR assays.

Hepatitis C virus subtype 3b infection in a hospital in Japan: epidemiological study

To elucidate the epidemiology of infection with hepatitis C virus (HCV) subtype 3b (a rare subtype thought to have originated in Southeast Asia) in Japan, we examined the genotypic subtype in 1397 patients with HCV-related chronic liver diseases. Of 1330 patients with identified HCV RNA genotypes. 960 had subtype 1b, 243 had subtype 2a, 97 had subtype 2b, 14 (1.1%) had subtype 3b, and 16 had other types of HCV or mixed subtypes. The age, gender, and severity of liver disease in patients with HCV subtype 3b did not differ from these features in patients with other subtypes. Eleven of the 14 patients with the 3b subtype had once worked at Company A in Tokyo, Japan. Multivariate logistic analysis showed that working history at that company was independently associated with the incidence of the subtype; the risk ratio was 207.2 (P < 0.0001). All 11 patients from Company A had received medical services, between 1953 and 1981, at Clinic C, which undertook medical care of the company staff. All 11 patients had received repeated intramuscular or intravenous injections for treatment of various diseases or for preventive vaccination for contagious diseases. The rare HCV subtype 3b, appeared to have been transmitted among the employees of a company through the performance of certain medical practices.

Hepatitis C virus genotypes in chronic hepatitis C of children

Several hepatitis C virus (HCV) genotypes have been recently identified and genotype 1b has been correlated with severe liver disease and a poor response to interferon therapy. HCV infection in children is an interesting model for evaluation of the relationship between HCV genotypes and liver disease, because of its relatively short duration and the infrequent association with confounding cofactors. We have investigated HCV genotypes, using a dot-blot hybridization assay with genotype-specific probes, in 36 Italian children with chronic hepatitis C who were otherwise well and had no other underlying disease. Only four patients were symptomatic; liver histology, obtained in 33 patients, showed minimal hepatitis in 17 and mild chronic hepatitis in 16. Infection with HCV genotype 1b was found in 55.5% of patients, with a peak prevalence of 83% in children from southern Italy (P < 0.05 vs other regions). The remaining children were infected with HCV genotype 1a (16.6%), genotype 2 (11.1%), and mixed (10.9%) or undetermined (2.7%) genotypes. In one patient, HCV viraemia was never detected. There was no statistically significant correlation between genotype and age, sex, source of infection, alanine aminotransferase pattern and histological activity index. These results indicate that genotype 1 b is widespread among Italian children with chronic hepatitis C, although with significant geographical variations. It is not associated with a more severe liver disease, therefore suggesting that the greater severity of liver disease recently reported in adults could reflect the cumulative effects of disease duration and of interfering cofactors.

Hepatitis C virus genotypes in Belgian hemophiliacs

Hemophiliacs who have been exposed to unheated and/or dry heated pooled clotting factor concentrates are at a high risk of chronic hepatitis C. Serum HCV-RNA was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) technique in 58 hemophiliacs positive for anti-HCV antibodies, HCV-RNA was detected in 55 patients. Based on the results of PCR positivity, HCV genotyping was carried out using genotype specific probes and the dot blot hybridization assay: 2 patients were found to be infected with type 1a (3.6%), 31 patients with type 1b (56.4%), 8 patients with type 2 (14.6%), 6 patients with type 3 (10.9%), 1 patient with type 4, and 7 patients with double infection (12.7%). As compared to a control group of 105 nonhemophilia patients with chronic hepatitis C, HCV genotype 1b was found predominant in both groups. However, double infection with two HCV types as well as a relatively high prevalence of infection with type 2 and type 3 were found in hemophiliacs.

Hepatitis C virus RNA detection and HCV genotype in patients with chronic non-A, non-B hepatitis in Jakarta

Antibody response in HCV infection may be variable and the variability of the serological response could be due to the differences in HCV strains. Since the distribution of hepatitis C virus genotype has been found to be geographically dependent, it is important to determine the distribution of HCV genotype in various countries with high prevalence of chronic non-A, non-B hepatitis. In this study, serum HCV RNA was examined in 53 patients suspected of chronic non-A, non-B hepatitis with an anti-HCV test as determined by currently available assay. HCV viremia was detected in 48 patients (90.6%). These patients had elevated serum ALT level at the time of HCV RNA determination. Using specific genotype probes, all isolates were classified into three different genotypes. Double and triple infections were also noted. HCV genotype 1b is the predominant genotype found in chronic hepatitis C patients in Jakarta.

Immune response to a hepatitis C virus nonstructural protein in chronic hepatitis C virus infection

The immune responses to a hepatitis C virus nonstructural protein (T3Ag) overlapping with the C100-3 antigen were examined in three groups of patients with chronic non-A, non-B hepatitis. Group I included 20 cases positive for both anti-C100-3 and the second-generation anti-HCV test (anti-HCV-II): Group II, five cases with anti-C100-3(-)/anti-HCV-II(+); and Group III, seven cases negative for both tests. HCV RNA was detectable in 20 (100%), 4 (80%) and 0 (0%) patients in each group, respectively. Proliferative responses of peripheral blood mononuclear cells to T3Ag were present in 16 (80%), 3 (60%) and 0 (0%) cases in each group, respectively (p < 0.05). Removal of CD8+ T cells from peripheral blood mononuclear cells resulted in a conversion of unresponsiveness to significant proliferation to T3Ag in the remaining cases in groups I and II, but not in group III. This change paralleled the antigen-induced production of interferon-gamma and interleukin-2, but not interleukin-4. The removal also enhanced the T3Ag-stimulated anti-C100-3 antibody production from cultured peripheral blood mononuclear cells in group II patients. These results indicate that the T3Ag-specific type 1 T helper cells play an important role in regulating anti-C100-3 antibody secretion in hepatitis C patients.

Genotype distribution of hepatitis C virus infection in Taiwan

To investigate the prevalence of genotype distribution of hepatitis C virus (HCV) infection in Taiwan, genotypes were identified in 122 (36 anti-HCV-positive blood donors, 44 anti-HCV-positive aborigines, 28 hemodialysis patients, and 14 patients with chronic liver diseases) of 280 subjects, using polymerase chain reaction by Okamoto's type-specific primer method. Type II was the dominant (66.7%) type among anti-HCV-positive blood donors, followed by type III and type IV with the same percentages (16.7%), while none of type I was detected. The prevalence of genotype distribution were 75.0%, 81.1%, and 64.3% for type II, 4.6%, 17.9%, and 21.4% for type III, 13.6%, 0%, and 7.1% for type IV, for the aborigines, hemodialysis, and chronic liver diseases groups, respectively. Four subjects revealed mixed infections by two different genotypes: two cases of II and III; and each one case of II and IV, and III and IV. Diverse genotype distributions in two hemodialysis groups disclose the existence of obvious regional differences even within a region. The results reveal the highest prevalence of type II as in Japan. However, there is a higher prevalence rate of type IV than in Japan.

Active hepatitis C virus infection in bone marrow and peripheral blood mononuclear cells from patients with mixed cryoglobulinaemia

The presence of hepatitis C virus (HCV) genomic sequences was checked in plasma, liver, peripheral blood mononuclear cells (PBMC) and bone marrow cells from 11 patients with mixed cryoglobulinaemia positive for anti-HCV antibodies, and from 11 patients with chronic HCV hepatitis without serological evidence of cryoglobulinaemia. HCV RNA sequences were demonstrated by reverse transcription polymerase chain reaction in seven plasma samples, in six PBMC samples, and in seven bone marrow cell samples from the 11 cryoglobulinaemic subjects; otherwise, viral specific nucleic acids were detected in 10 plasma samples, in one PBMC sample, and in two bone marrow cell samples from the 11 patients with chronic hepatitis. The HCV replicative intermediate was evidenced in four of the six PBMC and in five of the seven bone marrow aspirate HCV RNA-positive samples. Analysis of subpopulations isolated from bone marrow and peripheral blood samples showed HCV RNA sequences in mononuclear cells belonging either the CD2+ subset or to the CD19+ subpopulation or to the adherent cells. Finally, we compared the nucleotide sequences of a large portion (-270 to -59) of the HCV 5'-untranslated region from five patients with mixed cryoglobulinaemia and from seven patients with chronic hepatitis without cryoglobulinaemia; the degree of heterogeneity, compared with the prototype HCV sequence, was similar in both groups. These findings from two groups of HCV-infected patients indicate that transient or permanent active HCV infection of bone marrow and PBMC is frequent in anti-HCV-positive patients with mixed cryoglobulinaemia, and suggest that extra-hepatic infection may play a major role in influencing the pathophysiology of this infection as well as the viral persistence.

Presence of hepatitis C virus (HCV) genomic RNA and viral replicative intermediates in bone marrow and peripheral blood mononuclear cells from HCV-infected patients

The cellular tropism of hepatitis C virus (HCV) was studied in vivo in samples from patients with persistent HCV infection. Plasma, liver, peripheral blood mononuclear cell (PBMC), and bone marrow cell (BMC) samples from 15 subjects positive for anti-HCV antibodies were tested for the presence of HCV RNA sequences by reverse transcription PCR. Virus-specific RNA sequences were found to be present in liver samples from all subjects (100%), in plasma samples from 13 of 15 patients (86.7%), in PBMC samples from 3 patients (20%), and in BMC samples from 9 (60%) of the 15 anti-HCV-positive patients enrolled in this study. The presence of the molecular intermediate of HCV replication (the negative-stranded HCV RNA) was evident in the two of the three PBMC and in five of the nine BMC HCV RNA-positive samples. Finally, we studied the nucleotide sequence of a large portion (-270 to -59) of the 5'untranslated region of HCV amplified from plasma samples of 12 of the 15 patients with and without HCV in BMCs; the degree of heterogeneity compared with the prototype HCV sequence was similar in both groups. The data principally indicate that HCV infection of PBMCs and BMCs is frequent in persistently infected patients, as shown by the occurrence of positive- and negative-stranded HCV RNA, thus suggesting the possibility of extrahepatic replication of HCV.

Hepatitis C virus infection in pregnant women: detection by different anti-HCV immunoassays and serum HCV-RNA

To assess the seroepidemiology of hepatitis C virus (HCV) infection in pregnant women and explore the correlation between different anti-HCV immunoassays, we investigated 2 independent groups in Taipei: 1,687 pregnant women without screening for serum alanine aminotransferase (ALT) (group A) and 260 pregnant women with elevated ALT activity (> 45 IU/l) screened from 15,978 cases (group B). In group A, 11 women (0.65%) were found to be anti-HCV-positive by first-generation tests and 21 (1.24%) by second-generation tests, while 7 (2.69%) and 15 (5.77%) of the group B subjects were positive, respectively. The results of the second-generation assays, based either on recombinant proteins or synthetic peptides, were identical. Among the 36 second-generation anti-HCV-positive cases, 18 (86%) of the 21 cases in group A and 13 (87%) of the 15 cases in group B contained serum HCV-RNA by RT-PCR. We conclude that the prevalence of anti-HCV in pregnant Taiwanese women is 1.24%, and the prevalence is 5.77% among those with an elevated ALT level. HCV-RNA is present in 86% of the cases positive for anti-HCV. The discrepancy between positive anti-HCV and negative HCV-RNA in some pregnant women suggests that anti-HCV positivity in such cases may merely represent a past HCV infection or a fluctuating viremia.

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: an investigation of type-specific differences in geographic origin and disease

Because of the nucleotide sequence diversity of different isolates of hepatitis C virus, it has become important to clarify whether distinct genotypes of hepatitis C virus vary with respect to pathogenicity, infectivity, response to antiviral therapy and geographic clustering. We assessed nucleotide sequence variability in the 5' noncoding region of hepatitis C virus, using restriction enzymes to analyze the distribution of hepatitis C virus genotypes, in 80 patients with chronic hepatitis C virus infection. Genotypes were correlated with demographic, clinical and histological features. Thirty-seven patients were infected with type 1, 10 had type 2 and 8 had type 3, and another 23 were infected with a new distinct hepatitis C virus type now classified as type 4. Two were infected with variants whose classification are uncertain. Types 1, 2 and 3 were found in patients from the United Kingdom, southern Europe, Asia, Africa and South America. Nineteen of 23 type 4 genotype isolates were from Middle Eastern patients, compared with 0 of 37 type 1 isolates (p < 0.001). Of 21 Middle Eastern patients, 19 (90.4%) had type 4 hepatitis C virus (p = 0.001, odds ratio = 9). We found no significant difference between the mean ages or mean serum aminotransferase concentrations between the various types. Types 1, 2, 3 and 4 were found in patients with mild-to-moderate disease or severe disease. However, 21 of 29 (72.4%) patients with type 1 who underwent liver biopsy had severe chronic hepatitis, cirrhosis or hepatocellular carcinoma histologically; 8 had mild or moderate chronic hepatitis without cirrhosis (p = 0.03, odds ratio = 2.6).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Comparison of three different immunoassays and PCR for the detection of hepatitis C virus infection in pregnant women in Taiwan

To compare different hepatitis C virus (HCV) immunoassays and HCV-RNA in pregnant women, we investigated two independent groups: 1,687 cases without screening for serum alanine aminotransferase (ALT) (group A) and 333 cases with elevated ALT (> 45 IU/l) (group B), after screening 21,459 pregnant women. In group A, 11 (0.65%) and 21 (1.24%) were anti-HCV-positive by first- and second-generation tests, respectively, while in group B 8 (2.40%) and 19 (5.71%) were positive, respectively. The results revealed by second-generation assays based on either recombinant protein or synthetic peptides were identical, as were the anti-HCV titers in group B. Among 40 second-generation anti-HCV-positive cases, 18 (86%) of 21 in group A and 17 (89%) of the 19 in group B contained serum HCV-RNA by RT-PCR. Thus the prevalence of anti-HCV in Taiwanese pregnant women is 1.24% versus 5.71% in those with elevated ALT level.

Prevalence, infectivity, and risk factor analysis of hepatitis C virus infection in prostitutes

A population of 622 prostitutes in Taiwan was tested for antibodies to the hepatitis C virus (anti-HCV) using a synthetic peptide assay composed of representative determinants from capsid and nonstructural (NS) viral proteins. Seventy-four (12%) were positive and the remaining 548 (88%) were negative. Seventy-nine samples were retested by a second-generation anti-HCV assay composed of recombinant capsid and NS proteins of HCV. Both assays had a nearly perfect agreement (Kappa value = 0.91). Of the positive cases, 31% were positive for reactivity to capsid only. Most (60/74, 81%) of the cases positive for synthetic peptide assay were HCV RNA positive, indicating potential infectivity. On the basis of the results of synthetic peptide assay, univariate analysis showed that history of paid sex for longer than 6 months, blood transfusion, acupuncture, intravenous drug abuse, and age over 20 years were significant risk factors of HCV infection (P < 0.01). Elevated alanine aminotransferase levels (> 40 U/L) were positively associated with anti-HCV, while the presence of serum hepatitis B surface antigen was a negatively associated factor. Multivariate analysis revealed that history of paid sex for longer than 6 months and blood transfusion were positively associated with anti-HCV (P < 0.001). The latter only accounted for less than one fifth of the HCV-infected prostitutes. This study indicates strongly that sexual transmission is an important route for HCV infection in prostitutes. This risk group may spread HCV to other populations as a sexually transmitted disease.

Variability of the envelope regions of HCV in European isolates and its significance for diagnostic tools

Following the original description of HCV in 1989 a tremendous amount of sequence data is now available. Based on the 8 complete nucleotide sequences published so far at least 4 genotypes can be distinguished. Partial sequences of additional HCV isolates indicate the existence of further genotypes. A serological typing is not yet possible. For detection of virus, reverse transcription and amplification of the 5' non coding region is most commonly performed. This region of the genome is highly conserved among all isolates. In this study we used regions of the E1 and E2 gene in order to classify HCV isolates. The nucleotide sequences of regions in E1 and E2 gene of different European isolates from Germany, Croatia, Hungary, and Rumania were determined and compared to recently published RNA sequences of American and Japanese HCV isolates. The cDNA, obtained by reverse transcription of viral RNA extracted from sera was amplified by nested PCR, cloned and sequenced. Within 564 nucleotides (nt) of E1 we found 87-90% homology (and 89-92% homology at aa level) compared to sequences of Japanese origin and 73-74% homology (77-81% at aa level) compared to the prototype HCV sequence (ptHCV-I). In all characterized isolates the sequence of E2 (643 nucleotides) showed a homology of about 83% at the nucleotide level as compared to genotype II sequences, and a homology of about 70% to genotype I. Our results confirm the existence of two hypervariable regions in the E2 gene of genotype II sequences. Our results also indicate together with other reports from European HCV isolates that genotype II is predominant in Europe.

Replication of hepatitis C virus in peripheral blood mononuclear cells. Effect of alpha-interferon therapy

Hepatitis C virus (HCV) is a positive-stranded RNA virus which replicates through a negative-stranded RNA intermediate. Using a PCR procedure to detect positive and negative strands, we investigated the existence of HCV replication in lymphoid cells. Both positive and negative strands were found in the peripheral blood mononuclear cells (PBMC) of all patients (n = 10) with untreated chronic hepatitis C. No HCV sequences were detected in PBMC in any of the 8 healthy controls. Fifteen patients with chronic hepatitis C were studied at the end of a 12-month course of alpha-interferon therapy. The positive strand was detected in PBMC in all 9 non-responder patients, and the negative strand in 7. In contrast, in PBMC from responder patients (n = 6) the positive strand was found in 4 and the negative strand in only 2 cases. These results demonstrate that HCV can infect PBMC and replicate in these cells and that interferon seems to exert an inhibitory effect on this process. Persistence of HCV-RNA in PBMC may help explain disease relapse after successful interferon therapy.

Clinical evaluation of a newly established anti-HCV assay for the diagnosis of hepatitis C in Japan

To develop a more dependable method of diagnosing hepatitis C, serum anti-hepatitis C virus (HCV) was examined by using a new assay (anti-HCV second generation). The results were compared with those of either the conventional assay (anti-HCV first generation) or HCV-RNA analysis. With the first generation assay, anti-HCV was detected in 69% of post-transfusion acute hepatitis (AH), 44% of sporadic AH, 50% of needlestick exposed AH, 72% of chronic hepatitis (CH), 77% of liver cirrhosis (LC) and 86% of hepatocellular carcinoma (HCC). These results were remarkably increased by using the second generation assay (92% in post-transfusion AH, 72% in sporadic AH, 100% in needlestick exposed AH, 96% in CH, 96% in LC and 97% in HCC). Furthermore, in the early stages of AH (from 1-5 weeks after onset), anti-HCV was not detected in all 18 patients by the first generation assay, but was found in 10 of them by using the second generation assay. The failure to detect anti-HCV with the first generation assay was mainly due to a lack of the core region coding peptide (C22-3) in this assay. In the AH-resolving group, anti-HCV second generation did not disappear, but the titre tended to be lower than that in the CH-developing group. Thus, the second generation assay for anti-HCV was considered to be a more useful tool for not only the diagnosis of hepatitis C but also for determining prognosis.

Improved detection of hepatitis C virus RNA by reverse transcription and polymerase chain reaction

The polymerase chain reaction with prior reverse transcription of RNA into cDNA was applied to hepatitis C virus RNA detection in human serum samples of different origin. In order to eliminate false negative results, the following steps were optimized: RNA extraction, reverse transcription, and oligonucleotide primer selection. We compared different RNA extraction methods using guanidinium salt/detergent and proteinase K digestion/phenol extraction, and tested virus particle enrichment with polyethylene glycol precipitation and ultracentrifugation. RNA extraction with guanidinium salt/detergent was the most efficient method. Ultracentrifugation of single samples did not improve hepatitis C virus RNA detection. Polyethylene glycol precipitation performed poorly. Recombinant thermostable reverse transcriptase produced cDNA from fewer samples than did Moloney murine leukaemia virus reverse transcriptase. Nested oligonucleotide primers from the 5'-terminal non-coding region of the hepatitis C virus genome amplified cDNA from more samples than did primers from the coding regions. Thirty six anti-hepatitis C virus antibody positive samples were tested; nested primers (nucleotides 6 to 327 and 15 to 288) yielded 21 amplificates, whereas primers from the coding region produced 16 amplificates (nucleotides 4684-5276) and 5 amplificates (nucleotides 5166-5270), respectively. The most efficient combination of steps was RNA extraction with guanidinium salt solution, reverse transcription with Moloney murine leukaemia virus reverse transcriptase and nested polymerase chain reaction primed with primers from the 5'-terminal non-coding region of the hepatitis C virus genome. Other combinations produced more false negative results. Three different groups of anti-hepatitis C virus antibody positive individuals had markedly different viraemia patterns: Hepatitis C virus RNA was detected in the sera of only 10% of anti-hepatitis C virus antibody positive blood donors, but in 90% of anti-hepatitis C virus antibody positive patients with clinically manifest hepatitis C, and 90% of anti-hepatitis C virus antibody positive haemophiliacs who had received plasma products in the past which had not been virus-inactivated. No hepatitis C virus RNA could be detected in the sera of 450 anti-hepatitis C virus antibody negative blood donors with elevated serum alanine aminotransferase catalytic concentrations.

Transient immunoglobulin M antibody response to hepatitis C virus capsid antigen in posttransfusion hepatitis C: putative serological marker for acute viral infection

The development of serological assays for hepatitis C virus (HCV) has made specific diagnosis possible. However, markers useful in indicating acute-phase HCV infection have not been identified. By an immunoblotting method, we characterized the IgM and IgG antibody response against HCV capsid antigen in patients with HCV infection. Among 88% of patients with acute posttransfusion hepatitis C recruited in a prospective study, there was a transient IgM antibody response. The IgM antibody appeared shortly after onset of hepatitis (average 3.7 weeks), persisted for several months (average 18 weeks), and then disappeared. In contrast, the IgG antibody persisted long-term once it appeared. Among patients with chronic hepatitis C with milder disease activities (serum aminotransferase increase above normal levels of less than 4-fold), the IgM antibody was negative in the majority (72%). In those with acute exacerbations (aminotransferase increase of greater than 10-fold), about 55% were negative for the IgM antibody. The reactivity of the IgM antibody in the rest was weaker or became negative upon further dilution of serum. The results suggest that IgM anti-capsid antibody may serve as a marker indicating acute or active HCV infection.

Genomic typing of hepatitis C viruses present in China

Hepatitis C virus (HCV) genomic clones were obtained from the serum of Chinese HCV carriers using a polymerase chain reaction-based approach. Consensus sequences were derived from (1) the structural region (nt 1-1543) for one carrier, (2) the hypervariable region V (nt 1156-1233) from four carriers and (3) region V3 from four carriers. Region V3, located in the nonstructural domain NS5 (nt 7066-7137), has been previously shown to be a particularly good marker for the genomic typing of HCV isolates [Inchauspe et al., Proc. Natl. Acad. Sci. USA 88 (1991) 10292-10296]. Comparison of these sequences with sequences from geographically distinct HCV isolates indicates that Chinese HCV strains are closely related to, though distinguishable from, Japanese prototype strains. One amino acid motif, GGAA, located in region V, was found to be conserved only among Chinese isolates. This may define a new subgroup among HCV isolates.

Full-length sequence of a hepatitis C virus genome having poor homology to reported isolates: comparative study of four distinct genotypes

Variable genomic sequences have been reported for RNA cloned from hepatitis C virus (HCV)-infected humans and chimpanzees. We found that four distinct genotypes of HCV could be differentially identified by PCR using type-specific primers. Full-length sequences have so far been reported for three of the four HCV genotypes, and we report herewith the sequence of the fourth type obtained from a Japanese blood donor. The entire nucleotide sequence of the HCV isolate (HC-J8) comprised 9481 bases plus a 3'-terminal poly(U) stretch of variable length. Like all previous isolates, the RNA contained a single, long open reading frame for a polyprotein of 3033 amino acids. HC-J8 differed from previously reported HCV isolates by 23.1-33.1% in nucleotide sequence and 15.9-28.8% in amino acid sequence. Based on genomic sequence homologies, a proposed phylogenetic tree of HCV, with a fourth branch represented by HC-J8, allowed a classification of all HCV isolates whose complete or partial sequences are now known. This classification suggests that all or most HCV genome sequences will fall into one of the proposed four types. The classification may be helpful in designing vaccine studies and for serological investigations of possible group- and type-specific antibodies.

The Taiwanese hepatitis C virus genome: sequence determination and mapping the 5' termini of viral genomic and antigenomic RNA

The complete nucleotide sequence of hepatitis C virus (HCV) cloned from the liver tissue of a Taiwanese patient with post-transfusion type C hepatitis was determined. The 5' end of HCV genomic RNA was located 341 nucleotides upstream from the initiation codon for the viral polyprotein open reading frame. The 5' end of the viral antigenomic RNA was shown to have 13 consecutive As. Thus the 3' terminus of the viral genome is a stretch of U which ends about 50 nucleotides downstream from the stop codon of the large open reading frame. The nucleotide sequence homology between this HCV strain and two Japanese isolates was 90.5 and 90.7%, respectively. Homology with the United States strain, however, was only 77.8%. Accordingly, the indigenous Taiwanese HCV strain is of the same subtype as the Japanese isolates. Novel features of the viral genome termini are possibly relevant to HCV genome replication.