Isolation of a cDNA clone derived from a blood-borne non-A, non-B viral hepatitis genome.

A random-primed complementary DNA library was constructed from plasma containing the uncharacterized non-A, non-B hepatitis (NANBH) agent and screened with serum from a patient diagnosed with NANBH. A complementary DNA clone was isolated that was shown to encode an antigen associated specifically with NANBH infections. This clone is not derived from host DNA but from an RNA molecule present in NANBH infections that consists of at least 10,000 nucleotides and that is positive-stranded with respect to the encoded NANBH antigen. These data indicate that this clone is derived from the genome of the NANBH agent and are consistent with the agent being similar to the togaviridae or flaviviridae. This molecular approach should be of great value in the isolation and characterization of other unidentified infectious agents.

An assay for circulating antibodies to a major etiologic virus of human non-A, non-B hepatitis.

A specific assay has been developed for a blood-borne non-A, non-B hepatitis (NANBH) virus in which a polypeptide synthesized in recombinant yeast clones of the hepatitis C virus (HCV) is used to capture circulating viral antibodies. HCV antibodies were detected in six of seven human sera that were shown previously to transmit NANBH to chimpanzees. Assays of ten blood transfusions in the United States that resulted in chronic NANBH revealed that there was at least one positive blood donor in nine of these cases and that all ten recipients seroconverted during their illnesses. About 80 percent of chronic, post-transfusion NANBH (PT-NANBH) patients from Italy and Japan had circulating HCV antibody; a much lower frequency (15 percent) was observed in acute, resolving infections. In addition, 58 percent of NANBH patients from the United States with no identifiable source of parenteral exposure to the virus were also positive for HCV antibody. These data indicate that HCV is a major cause of NANBH throughout the world.

HLA class I-restricted cytotoxic T lymphocytes specific for hepatitis C virus. Identification of multiple epitopes and characterization of patterns of cytokine release.

Cytotoxic T lymphocytes (CTL) are important to the control of viral replication and their presence may be important to disease outcome. An understanding of the spectrum of proteins recognized by hepatitis C virus (HCV)-specific CTL and the functional properties of these cells is an important step in understanding the disease process and the mechanisms of persistent infection, which occurs in the majority of HCV-infected individuals. In this report we identify HCV-specific CTL responses restricted by the HLA class I molecules A2, A3, A11, A23, B7, B8, and B53. The epitopes recognized by these intrahepatic CTL conform to published motifs for binding to HLA class I molecules, although in some cases we have identified CTL epitopes for which no published motif exists. The use of vectors expressing two different strains of HCV, HCV-1 and HCV-H, revealed both strain-specific and cross-reactive CTL. These HCV-specific CTL were shown to produce cytokines including IFN-gamma, TNF-alpha, GM-CSF, IL-8, and IL-10 in an antigen- and HLA class I-specific manner. These studies indicate that the CTL response to HCV is broadly directed and that as many as five different epitopes may be targeted in a single individual. The identification of minimal epitopes may facilitate peptide-specific immunization strategies. In addition, the release of proinflammatory cytokines by these cells may contribute to the pathogenesis of HCV-induced liver damage.

Role of hepatitis C virus in non-B chronic liver disease.

To assess the contribution of the recently identified hepatitis C virus to chronic liver diseases of unknown cause and chronic hepatitis attributed by exclusion to non-A, non-B hepatitis, we tested for antibody to hepatitis C in hepatitis B surface antigen-negative patients with a spectrum of chronic liver diseases. Antibody to hepatitis C virus, a marker of hepatitis C infection, was detected with a first-generation radioimmunoassay at the following frequencies in the following patient groups: 69% of transfusion-associated non-A, non-B hepatitis; 53% of non-transfusion-associated non-A, non-B hepatitis; 26% of hepatitis B surface antigen-negative hepatocellular carcinoma; 8% of cryptogenic cirrhosis; 5% to 7% of autoimmune chronic liver diseases; 19% of patients with miscellaneous types of chronic liver disease; and 0.67% of healthy controls. Among non-transfusion-associated cases, 81% with a history of intravenous drug use but only 18% with occupational exposure as health workers had antibody to hepatitis C virus. Among cases of hepatocellular carcinoma, 63% of Japanese patients but only 11% of American patients had evidence of hepatitis C infection. Comparison in a subgroup of 79 serum samples of a second-generation radioimmunoassay with the first-generation assay demonstrated a 12% increase in antibody frequency from 30% to 42%. We conclude that hepatitis C plays a substantial role in transfusion-associated and non-transfusion-associated non-A, non-B hepatitis as well as in hepatocellular carcinoma, especially in Japan, a limited role in cryptogenic cirrhosis, and essentially no role in autoimmune chronic liver diseases. Application of more sensitive immunoassays will increase the frequency of antibody seropositivity in all subgroups, but relative distinctions among risk groups are likely to remain.

Hepatitis C viral cDNA clones isolated from a healthy carrier donor implicated in post-transfusion non-A, non-B hepatitis.

Using a specific hepatitis C virus (HCV) antibody assay, positive blood donors responsible for the transmission of post-transfusion non-A, non-B hepatitis (PT-NANBH) were identified. cDNA fragments were isolated from one of the plasma samples of such healthy HCV carriers by using polymerase chain reactions. Nucleotide (nt) sequence analyses of the cDNA from three different regions of the viral genome revealed that they were derived from a Japanese HCV isolate that was similar but not identical to the prototype HCV previously isolated from a chronically infected chimpanzee. Homology at the nt and amino acid levels was comparatively lower in the presumed structural region than in putative nonstructural regions. This result not only confirms that HCV antibody-positive blood contains infectious HCV, but suggests the existence of different type(s) of HCV.

Vimentin and 70K neurofilament protein co-exist in embryonic neurones from spinal ganglia.

The mesenchymal intermediate filament protein vimentin and the 70K component of neurofilament were detected by two-dimensional gel electrophoresis in cultures of pure sensory and sympathetic neurones derived from chick embryos. The identities of these neuronal intermediate filament proteins were confirmed by comparison of their molecular weights, isoelectric points, and peptide patterns from limited papain digestions with those of the corresponding proteins from fibroblasts and brain, respectively. A specific antibody to vimentin stained filamentous structures and colcemid-induced coils in both neurones and associated satellite cells. In contrast, a specific antibody to the 70K neurofilament protein stained these structures solely in neurones. This neurone-specific staining, as well as its molecular weight and isoelectric point, distinguishes the 70K neurofilament protein from the 68K neurofilament associated protein described by others, which has been claimed to resemble the tubulin assembly protein.

Hepatitis C virus antibodies in southern African blacks with hepatocellular carcinoma.

380 southern African blacks with hepatocellular carcinoma and 152 controls were studied. Antibodies to hepatitis C virus (HCV) were found in 110 patients and 1 control. 184 patients had evidence of current infection with hepatitis B virus (HBV) and 122 had had infection with this virus in the past. Only 47 patients had no markers of HCV or HBV infection. Among patients positive for HCV, there was a higher proportion of women and urban dwellers, and the average age was higher. In southern Africa, HCV is associated with hepatocellular carcinoma but HBV is present in a higher proportion of patients.

Hepatitis C virus antibodies in acute icteric and chronic non-A, non-B hepatitis.

Hepatitis C virus antibodies were measured in 213 patients who had acute (n = 122) and chronic (n = 91) non-A, non-B hepatitis. In acute infection, anti-hepatitis C virus was detected in 61% of IV drug abusers, in 33% of patients with transfusion-associated hepatitis, and in 22% of patients with sporadic infections (P less than 0.0005, drug abusers vs. sporadic). Mean time to seroconversion was 11.6 weeks (range, 1-80 weeks). Anti-hepatitis C virus was more common in chronic infection (P less than 0.001) and was more often detected in IV drug users (89%; P less than 0.0001) and after transfusion (71%; P less than 0.005) compared with chronic sporadic infection (27%). Antibody persisted for up to 8 years. Six chronic case patients (8.3%) later lost antibody (mean, 24 months; range, 12-48 months).

Activation of the grp78 and grp94 promoters by hepatitis C virus E2 envelope protein.

The hepatitis C virus E1 and E2 envelope proteins are targeted to the endoplasmic reticulum, but instead of being secreted, they are retained in a pre-Golgi compartment, at least partly in a misfolded state. Since secretory proteins which are retained in the endoplasmic reticulum frequently can activate the transcription of intraluminal chaperone proteins, we measured the effect of the E1 and E2 proteins on the promoters of two such chaperones, GRP78 (BiP) and GRP94. We found that E2 but not E1 protein activates these two promoters, as assayed by a reporter gene system. Furthermore, E2 but not E1 protein induces the synthesis of GRP78 from the endogenous cellular gene. We also found that E2 but not E1 protein expressed in mammalian cells is bound tightly to GRP78. This association may explain the ability of E2 protein to activate transcription, since GRP78 has been postulated to be a sensor of stress in the endoplasmic reticulum. Since overexpression of GRP78 has been shown to decrease the sensitivity of cells to killing by cytotoxic T lymphocytes and to increase tumorigenicity and resistance to antitumor drugs, this activity of E2 protein may be involved in the pathogenesis of hepatitis C virus-induced diseases.

Hepatitis delta (delta) cDNA clones: undetectable hybridization to nucleic acids from infectious non-A, non-B hepatitis materials and hepatitis B DNA.

Hepatitis Delta (delta) cDNA clones were hybridized to RNA extracted from livers of chimpanzees infected with the blood-borne Non-A, Non-B hepatitis (NANBH) agent(s) and to total nucleic acids extracted from chimpanzee plasma containing a high titer of these NANBH agent(s). Since no hybridization was observed, the data suggests that the hepatitis Delta viral genome is not closely related to the genome(s) of the NANB agent(s). Our studies, in which the Hepatitis B virus genomic DNA was hybridized to hepatitis Delta cDNA clones, also confirm and extend previous studies [Hoyer et al, 1983], which report a lack of detectable homology between the hepatitis Delta genome and HBV DNA.

Hepatitis C antibody and chronic liver disease in haemophilia.

A radioimmunoassay was used to detect antibodies to hepatitis C virus (anti-HCV) in 154 patients with haemophilia. Prevalence of anti-HCV was associated with exposure to clotting factor concentrates. 76 of 129 (59%) who had received factor VIII or IX had anti-HCV: 42 of 55 (76%) who required over 10,000 units of concentrate annually had anti-HCV, compared with 34 of 74 (46%) who required less, and 0 of 25 patients who had never received concentrates. Anti-HCV were significantly more common in patients seropositive for antibodies against human immunodeficiency virus (anti-HIV) or with markers of previous hepatitis B infection than in those without anti-HIV or hepatitis B markers (88% vs 39% and 75% vs 46%, respectively). 5 of 23 (22%) haemophiliacs treated only with heated concentrates had anti-HCV compared with 71 of 106 (67%) patients who received unmodified products. 35 patients with chronic liver disease underwent liver biopsy: histological examination showed features associated with post-transfusion hepatitis in 24, all of whom were anti-HCV-positive; of the other 11 patients with no histological features of non-A, non-B hepatitis, 5 were anti-HCV-positive. HCV appears to be the major predisposing factor for most non-A, non-B hepatitis and chronic liver disease in haemophilia.

Epidemiology of hepatitis C virus. A preliminary study in volunteer blood donors.

In a survey carried out from 1985 through 1986, volunteer blood donors to The Greater New York Blood Program were tested for two surrogate markers for non-A, non-B hepatitis--elevation of alanine aminotransferase level and presence of antibody to hepatitis B core antigen. Stored serum samples from selected donors were also recently tested for antibody to hepatitis C virus (anti-HCV). Anti-HCV was detected in 0.9% to 1.4% of donors and was higher in black and Hispanic donors than in white donors. Anti-HCV prevalence increased with increasing age through the fourth decade of life, but decreased thereafter, possibly reflecting the disappearance of detectable antibody with time. Anti-HCV correlated with both alanine aminotransferase level and the presence or absence of antibody to hepatitis B core antigen. These associations suggest that donor screening for elevation of alanine aminotransferase level and presence of antibody to hepatitis B core antigen was, as expected, at least partially effective in preventing transfusion-associated non-A, non-B hepatitis. The detection of anti-HCV in donors who have neither an elevation of alanine aminotransferase level nor presence of antibody to hepatitis B core antigen suggests that donor screening for anti-HCV will further reduce the risk of transfusion-associated hepatitis.

Detection of antibody against antigen expressed by molecularly cloned hepatitis C virus cDNA: application to diagnosis and blood screening for posttransfusion hepatitis.

A cDNA clone has been derived from the plasma of a chimpanzee with chronic non-A, non-B viral hepatitis (NANBH). We have assayed for antibodies reacting with the encoded antigen in sera from posttransfusion hepatitis patients (643 samples from 23 patients) and their corresponding donors collected during the past 10 years in Japan. The antibody was detected in 15 out of 17 (88.2%) posttransfusion NANBH (PT-NANBH) patients whose sera over time displayed multiple alanine aminotransferase (ALT) peaks. In general, the antibody was detected after several peaks of serum ALT elevations and, once detected, it persisted for years. In contrast to the patients of chronic hepatitis, the antibody was barely detected in patients with a single episode of ALT elevation (1 out of 6). Of the 15 well-defined cases of PT-NANBH that showed multiple ALT peaks and hepatitis C virus seroconversions, 11 (73.3%) were shown to be transfused with at least one unit of blood positive for the antibody. The retrospective analysis showed that all tested donor blood found to be positive for the antibody had been transfused to recipients who afterwards developed NANBH. These data strongly suggest that the cloned cDNA originated from an etiological agent of NANBH termed the hepatitis C virus. Furthermore, the present study demonstrates that had the screening been done with the anti-hepatitis C virus assay, 11 out of 17 (64.7%) cases of chronic PT-NANBH and 1 out of 6 (16.6%) acute PT-NANBH would have been prevented. The antibody assay thus can be used for diagnosis and blood screening for PT-NANBH.

Hepatitis C virus: the major causative agent of viral non-A, non-B hepatitis.

A 'blind' recombinant immunoscreening approach, of general application to studies of infectious diseases, was used to clone and identify the genome of the previously uncharacterized non-A, non-B hepatitis (NANB) virus. This agent is a positive-stranded RNA virus that appears to be distantly related to the flaviviridae family. A recombinant viral antigen (C100-3) was used to develop a capture assay for circulating antibody. Data obtained using this assay indicate that this agent, termed the hepatitis C virus (HCV), is the major cause of post-transfusion, community-acquired and cryptogenic, NANB. Anti-C100-3 antibody appears to be directed towards dominant, non-structural viral epitopes. It is a non-neutralising antibody that develops generally late in infection and is a particularly good marker of chronic, persistent viraemia. Many asymptomatic but infectious blood donors can now be detected using this antibody assay. HCV is associated with the development of hepatocellular carcinoma and possibly, other liver diseases.

Blood screening for non-A, non-B hepatitis by hepatitis C virus antibody assay.

Hepatitis C virus (HCV) antibody was detected in 1499 donor sera by radioimmunoassay using an antigen expressed in yeast from a cDNA clone of the HCV genome. Eighteen samples over 4200 counts per minute (cpm) were considered to contain infectious HCV because these recipients developed typical posttransfusion non-A, non-B hepatitis after transfusion. The antibody-positive sera were all within the normal range of ALT levels. This assay system is thus useful for the screening for blood transfusion.

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.

Hepatitis C virus-specific CTL responses in the liver of chimpanzees with acute and chronic hepatitis C.

Hepatitis C virus (HCV)-specific CTL responses were evaluated in two chimpanzees (Pan troglodytes) during the acute and chronic phases of HCV infection. CD8+ T lymphocytes were isolated from liver tissue homogenates using anti-CD8 antibody-coated magnetic beads and then stimulated with anti-CD3 antibodies, IL-2, and irradiated human PBMC using limiting dilution culture conditions. HCV-specific cytotoxic activity of expanding CD8+ cell lines was assessed against autologous lymphoblastoid cell lines infected with recombinant vaccinia virus vectors encoding HCV Ag. CD8+ T cell lines specific for structural and nonstructural proteins of HCV were established from both animals. Cytolytic activity was blocked with anti-CD8 or anti-class I MHC antibodies, indicating that class I MHC molecules were involved in presentation of viral Ag to the CTL. Overlapping synthetic peptides were used to define a 12 amino acid segment of the nonstructural 3 (NS3) protein recognized by CTL lines from both chimpanzees. Studies with truncated peptides revealed that these CD8+ cell lines were directed against overlapping epitopes presented by distinct class I restriction elements of the chimpanzee MHC complex. CD8+ cell lines with identical specificities for an NS3 epitope were generated from one chronically infected animal at 16 and 28 wk postinfection. These results indicate that virus-specific CTL populations persist in the liver for months, but are unable to resolve chronic HCV infection.

Structure of two related rat pancreatic trypsin genes.

A family of approximately 10 trypsin genes was detected in a rat genomic library by hybridization and in vivo recombination techniques using cloned rat pancreatic trypsin I and II cDNAs as probes. Two separate clones containing the entire trypsin I gene and most of the trypsin II gene were sequenced. Four introns split the trypsin I coding sequence. The positions of the first three introns of the trypsin II gene are identical with those in the trypsin I gene (the fourth intron was not present in the trypsin II clone). The coding regions of the two genes are 88% homologous; the 5'-noncoding regions are 92% homologous, whereas the 3'-noncoding regions share 66% identity. In contrast, the proximal 5'-flanking regions from -1 to -500 which may contain the elements controlling gene expression are less than 30% conserved overall, but segments of approximately 70% homology can be discerned in this region. Some of these sequences are homologous to sequences found in the chymotrypsin and elastase genes. More distal upstream sequences (-500 to -2500) and the intervening sequences show no evident sequence homology (less than 20%). Unique sequences containing homopolymeric purine/pyrimidine repeats are found 2.5 kilobases upstream from the start of transcription of the trypsin I gene and within the second and third introns of the trypsin II gene. The nucleotide homologies as well as the similarities of intron positions of the two trypsin genes to those of other serine protease genes clearly support an evolutionary relationship between members of this gene family.

Characterization of hepatitis C virus envelope glycoprotein complexes expressed by recombinant vaccinia viruses.

We constructed recombinant vaccinia virus vectors for expression of the structural region of hepatitis C virus (HCV). Infection of mammalian cells with a vector (vv/HCV1-906) encoding C-E1-E2-NS2 generated major protein species of 22 kDa (C), 33 to 35 kDa (E1), and 70 to 72 kDa (E2), as observed previously with other mammalian expression systems. The bulk of the E1 and E2 expressed by vv/HCV1-906 was found integrated into endoplasmic reticulum membranes as core-glycosylated species, suggesting that these E1 and E2 species represent intracellular forms of the HCV envelope proteins. HCV E1 and E2 formed E1-E2 complexes which were precipitated by either anti-E1 or anti-E2 serum and which sedimented at approximately 15 S on glycerol density gradients. No evidence of intermolecular disulfide bonding between E1 and E2 was detected. E1 and E2 were copurified to approximately 90% purity by mild detergent extraction followed by chromatography on Galanthus nivalus lectin-agarose and DEAE-Fractogel. Immunization of chimpanzees with purified E1-E2 generated high titers of anti-E1 and anti-E2 antibodies. Further studies, to be reported separately, demonstrated that purified E1-E2 complexes were recognized at high frequency by HCV+ human sera (D. Y. Chien, Q.-L. Choo, R. Ralston, R. Spaete, M. Tong, M. Houghton, and G. Kuo, Lancet, in press) and generated protective immunity in chimpanzees (Q.-L. Choo, G. Kuo, R. Ralston, A. Weiner, D. Chien, G. Van Nest, J. Han, K. Berger, K. Thudium, J. Kansopon, J. McFarland, A. Tabrizi, K. Ching, B. Mass, L. B. Cummins, E. Muchmore, and M. Houghton, submitted for publication), suggesting that these purified HCV envelope proteins display native HCV epitopes.

Expression, identification and subcellular localization of the proteins encoded by the hepatitis C viral genome.

We have expressed the full-length coding region and selected domains of the hepatitis C virus (HCV) cDNA in mammalian cells by transfection. Using HCV antibody-positive human sera and monospecific antibodies the proteins encoded by the putative structural and non-structural regions of the open reading frame of HCV were identified as core (p22), E1 (gp32-35), E2 (gp68-72), NS2 (p23), NS3 (p72), NS4a and b (p10 and p27) and NS5a and b (p56 and p70). We have also defined the subcellular localizations of the HCV proteins using indirect immunofluorescence assays.