Cloning of a cDNA associated with acute and chronic hepatitis C infection generated from patients serum RNA

Decrease of CD56(+)T cells and natural killer cells in cirrhotic livers with hepatitis C may be involved in their susceptibility to hepatocellular carcinoma

CD56(+)T cells and CD56(+)natural killer (NK) cells are abundant in the human liver. The aim of this study was the further characterization of these cells in the liver with or without hepatitis C virus (HCV) infection. Liver mononuclear cells (MNC) were isolated from liver specimens obtained from the patients during abdominal surgery. In addition to a flow cytometric analysis, liver MNC and PBMC were cultured with the immobilized anti-CD3 Ab, IL-2, or a combination of IL-2 and IL-12 and their IFN-gamma production and the antitumor cytotoxicity were assessed. The liver MNC of HCV (-) patients contained 20% CD56(+)T cells whereas the same proportions decreased to 11% in chronic hepatitis livers and to 5% in cirrhotic livers. The proportion of NK cells also decreased in the cirrhotic livers. On the other hand, the populations of these cells in PBMC did not significantly differ among patient groups. The IFN-gamma production and the cytotoxicity against K562 cells, Raji cells, and a hepatocellular carcinoma, HuH-7 cells, greatly decreased in the cirrhotic liver MNC. In contrast, the cytotoxicity in PBMC did not significantly differ among the patient groups and was lower than that in the liver MNC of HCV (-) patients. CD56(+)T cells and NK cells but not regular T cells purified from liver MNC cultured with cytokines showed potent cytotoxicities against HuH-7 cells. These results suggest that a decreased number of CD56(+)T cells and NK cells in cirrhotic livers may be related to their susceptibility to hepatocellular carcinoma.

Hepatitis C virus screening and intravenous immunoglobulin safety in Japan

To obtain safe blood products, contaminants in source plasma must be eliminated through screening. Second-generation agglutination tests performed as part of donor screening have been shown to reduce the risk of hepatitis C virus (HCV) infection to 0.024% (1/4124) per unit of donated blood. These tests, as well as the third-generation enzyme-linked immunosorbent assay, significantly shortened the window of infectivity (the period between infection and antibody production) through more sensitive and specific recognition of anti-HCV antibodies in early-stage HCV infection. Earlier detection may reduce the risk of contamination of plasma with the high viral load that can be present in early-stage HCV infection without detectable anti-HCV antibodies. Because alanine aminotransferase levels increase before detectable seroconversion occurs in the window of infectivity, screening for alanine aminotransferase levels was found to be useful in determining which sources of plasma should be eliminated because of HCV contamination.

Molecular cloning of HCV and clinical application

Fifty-five clones encoding epitopes of HCV were isolated from Japanese patients. Their amino acid homology (AAH) to the sequence of prototype (HCV-1) ranged from 47% to 94%. These sequences cover 60% of the HCV genome lacking M/E and NS2 regions suggesting a very low or lacking immunogenicity for these regions. Two test kits for detection of anti-HCV antibody were developed using a combination of a synthetic peptide (AR142) containing the epitope of N14 (QRKTKRSTNRR) having a homology to the core of HCV of 8/11AA and a non-fusion recombinant protein Y19 starting from amino acid number (AAN) 1380 to 1507 in the NS3 region showing a AAH to the HCV-1 of 90%, and a combination of a mixture of three synthetic peptides of S29 AAN of 1-30, 38-65 and 47-74 of the core and a non-fused recombinant protein S4 AAN of 1287-1506 having a 93% AAH of the NS3 region. They showed almost the same order of sensitivity and specificity of the second-generation kits when tested with serum from blood donors and patients with non-A, non-B hepatitis. It should also be stressed that in all of the complete responders of a recombinant alpha-interferon therapy, the antibody levels against AR142 gradually decreased during and after the treatment. In 1992, studies performed for 125 patients with hepatocellular carcinoma in our clinic shows that of these 16 patients might developed from either chronic non-B, non-C liver diseases or chronic liver diseases caused by mutant(s) of HCV as their serum were negative for HBsAg and second-generation of anti-HCV.

Liver disease

Images

Clone Q379 immunoscreened from a Chinese HCV cDNA lambda gt11 library

A Chinese HCV cDNA clone, designated as Q379, 379 nucleotides in length, was selected by recombinant immunoscreening from a random-primed Chinese HCV lambda gt11 library. DNA sequencing demonstrated that Q379 situated from positions 7314 to 7695 at NS5 region corresponded with the American prototype HCV nucleotide sequence. The homologies of Q379 with the equivalent sequences of the prototype were found to be 72.8% in nucleotides and 73.8% in amino acids, respectively. Hydrophobicity profile shows that Q379-encoded polypeptide (126 amino acid residues) contains two hydrophilic areas. This Chinese HCV clone would be valuable in basic and clinical studies of Chinese HCV infection.

Clinical course of acute hepatitis C and changes in HCV markers

Chronological measurements of various HCV markers were conducted to clarify the course and prognosis of acute hepatitis C. Among 49 patients with acute non-A, non-B hepatitis, 32 (65.3%) were diagnosed as having acute hepatitis C by these markers. Twenty-four (82.8%) of 29 patients with posttransfusion hepatitis were type C, while only eight (40.0%) of 20 patients with sporadic hepatitis were type C. Patients were also divided into those who returned to normal within one year based on changes in s-ALT levels and unresolved cases. Anti-HCV was present in 11 (44.4%) of 25 resolved cases and in 21 (87.1%) of 24 unresolved cases. Only one case was continuously positive for HCV-RNA although s-ALT levels returned to normal. In addition, quantitative determinations were conducted on those positive for anti-HCVs. Anti-second generation tested positive in all HCV-RNA-positive cases and positive rates were highest from the onset of hepatitis. In unresolved patients with continuous HCV infection, anti-core increased and titers at 12 months were 10 units or more in all cases. On the other hand, in eight of 10 resolved cases, titers declined gradually after initial seroconversion and titers were 10 units or less at 12 months. From these results, second generation anti-HCV was considered most useful in early diagnosis of acute hepatitis C and anti-core titer was considered most useful in predicting prognosis of acute hepatitis C.

Predictive value of screening tests for persistent hepatitis C virus infection evidenced by viraemia. Japanese experience

In November 1989, Japanese Red Cross Blood Centres started screening for hepatitis C virus (HCV) with enzyme-linked immunosorbent assay (Elisa) for the C100-3 viral peptide as the first such nationwide programme in the world. Thereafter post-transfusion non-A non-B hepatitis (PTNANBH) was reduced by 61-80%, but this was not as complete a success as our programme to prevent post-transfusion hepatitis B by screening for high titer hepatitis B core antibody, which we began in the same period. In order to acquire more effective control of PTNANBH, the HCV core-related antigen (GOR, N14) and second-generation Elisa (Ortho2, Abbott2) and second-generation antigen agglutination (PA, PHA) tests have been employed. Among 16,500 donors in 11 blood centers, 365 were serologically positive by at least one of these tests. Among these, HCV RNA was detected in 138 units and the remaining 227 were HCV RNA negatives. The effectiveness of these serological tests to detect HCV RNA-positive status were analyzed. Passive haemagglutination and particle agglutination (PHA and PA) tests were highly effective to predict HCV viraemia among blood donors. Also, these tests can easily determine antibody titre. By either PHA or PA, all units with > or = 2(12) agglutination titre (120 and 122 units) were HCV RNA positive and all agglutination-positive units with serum alanine aminotransferase level higher than 35 Karmen units were HCV RNA positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-HCV immunoglobulin M antibody in patients with acute and fulminant hepatitis C

To determine whether detection of IgM type antibody (Ab) to hepatitis C virus (HCV) antigens would be useful in the early diagnosis of type C acute hepatitis (AH) or fulminant hepatitis (FH), we assayed serum IgM and IgG type Abs to nonstructural (C100-3) and core (AR 142) antigens of HCV in patients with type C hepatitis. Of 8 patients with AH, anti-C100-3 IgM and anti-AR 142 IgM were positive in 1 and 6 patients, respectively. Early appearance of Anti-AR 142 IgM was observed in all of these 6 patients, and in 4 anti-AR 142 IgM was the sole serological marker of HCV infection during the acute-phase. However, the anti-AR 142 IgM response was rather persistent, not transient in AH. Only 1 patient with AH was positive for anti-C100-3 IgM, and this patient became positive for anti-AR 142 IgM 3 months before the appearance of anti-C100-3 IgM. The titre of anti-AR 142 IgM in AH was not dependent on the activity of hepatitis or on the duration. Anti-AR 142 IgM was also positive in 30-75% cases with chronic HCV carriers. Thus it is suggested that the detection of anti-AR 142 IgM may contribute to the early diagnosis of type C AH, although the appearance of this marker in chronic HCV carriers limits its usefulness as the sole serological marker of acute HCV infection.

Development of a specific enzyme-linked immunosorbent assay for the hepatitis C virus antibody using clone 14

The authors isolated a specific cDNA clone (clone 14) for non-A, non-B hepatitis virus infection. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) using a synthetic oligopeptide encoded by clone 14 and examined its usefulness for detecting hepatitis C virus (HCV) antibody in 181 patients with chronic NANB hepatitis, 88 with cirrhosis and 24 with hepatocellular carcinoma associated with NANB hepatitis virus. Anti-clone 14 antibody was detected in 75% of patients with chronic NANB hepatitis, 57% of cirrhotic patients and 58% hepatocellular carcinoma patients. Anticlone 14 and anti-C-100 antibody assayed using a commercial kit were found in serum from 199 (69%) and 205 (70%) of these 294 patients, respectively. Approximately 85% of the patients showed the presence of anticlone 14 and/or anti-C-100 antibodies. We compared the presence of these antibodies and the second generation anti-HCV antibody using ELISA and HCV RNA by the polymerase chain reaction assay, in the same blood samples from 49 patients with chronic liver disease who had anti-clone 14 and/or anti-C-100 antibody. HCV RNA was detected in 38 of 40 (95%) plasma samples containing anti-clone 14 antibody, the prevalence of which was similar to that for anti-C-100 antibody (41/42, 98%) and the second generation anti-HCV antibody (46/47, 98%). Furthermore, 6 of 7 plasma samples containing anti-clone 14 antibody and lacking anti-C-100 antibody were positive for the second generation anti-HCV antibody and HCV RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Estimation of IgG subclasses of anti-HCV (C100-3) in non-A, non-B fulminant, acute and chronic hepatitis and it's significance

To determine whether identification of subclasses of anti-HCV IgG would help distinguish between acute and fulminant hepatitis, we assayed serum IgG subclasses of anti-HCV (C100-3) in non-A, non-B hepatitis. Anti-HCV IgG was restricted to two subclasses in different diagnostic conditions; anti-HCV IgG1 and anti-HCV IgG3. Anti-HCV IgG1 was the main subclass in acute hepatitis (AH), and was positive in all the cases and only one case was positive for anti-HCV IgG3. Anti-HCV IgG3 was the dominant subclass in fulminant hepatitis (FH). Out of the total 12 cases of FH, who were positive for either anti-HCV IgG or for any of it's subclasses, in 10 cases (83%), anti-HCV IgG3 had higher optical density (OD) values than anti-HCV IgG1 and in 6 cases (50%) was the only subclass of anti-HCV IgG being positive. In 5 cases with FH, anti-HCV IgG3 became positive even when anti-HCV IgG was negative. These findings from the basis of a new observation and are likely to be helpful in the diagnosis of non-A, non-B fulminant hepatitis.

Identification of hepatitis C viruses with a nonconserved sequence of the 5' untranslated region

The nucleotide sequence of the 5' untranslated region of hepatitis C virus (HCV) has been shown to be conserved. In contrast, we have detected more sequence variation in this region in several HCV isolates than hitherto expected. The nucleotide sequences of the 5' untranslated regions of these isolates differ significantly from that of the prototype but are very similar to each other. We believe that these isolates belong to the same type of HCV. Among 240 HCV RNA polymerase chain reaction-positive specimens that we examined, 7 belong to this type. The results suggest that the HCV variants that we detected represent a different type of HCV and that they are responsible for approximately 3% of HCV infections in patients that we have examined.

Detection of intrahepatic replication of hepatitis C virus RNA by in situ hybridization and comparison with histopathology

A nonisotopic in situ hybridization (NISH) assay was used to detect hepatitis C virus (HCV) RNA. A synthetic oligonucleotide complementary to bases 252-301 of the highly conserved 5' noncoding region of the HCV genome was end-labeled by terminal deoxynucleotidyltransferase using digoxigenin-conjugated dUTP. The hybridized oligomer was revealed by an immunohistochemical reaction after incubation with an alkaline phosphatase-conjugated anti-digoxigenin antibody and subsequent amplification with a complex of alkaline phosphatase and anti-alkaline phosphatase antibodies. The intracellular distribution of HCV RNA was monitored in the livers of two chimpanzees experimentally infected with the H strain of HCV and compared with the serum alanine aminotransferase activity, serum HCV RNA, and liver histopathology. Most cells were stained in the cytoplasm as early as 2 days after inoculation, 1 and 2 days, respectively, before the appearance of viral RNA in the serum. The time course of HCV RNA replication was correlated with increases in serum alanine aminotransferase. However, neither one paralleled the appearance of liver cell necrosis nor showed any correlation with the inflammatory response. The NISH signal was not found in liver biopsy specimens taken from these two animals before inoculation with HCV, from chimpanzees with acute hepatitis type A, B, or delta, or from two animals never experimentally infected with any hepatitis agent; moreover, it disappeared when the positive specimens were predigested with RNase and it was not observed after hybridization of positive controls with a labeled oligomer unrelated to HCV RNA. Thus, detection of liver HCV RNA by NISH is a sensitive and specific method for studying HCV replication at the cellular level. Intracellular replication of HCV did not appear to be associated with histopathologic changes in the liver, although the correlation with increases of liver enzyme activity in the serum suggested possible damage to the liver cell membrane.

A cDNA clone closely associated with non-A, non-B hepatitis

A lambda gt11 cDNA library was constructed from RNA purified from hepatitis B viral surface antigen-negative human plasma with high alanine aminotransferase activity. A cDNA clone, designated as C8-2, was isolated by immunoscreening with mixed sera from non-A, non-B hepatitis (NANBH) carrier and convalescent chimpanzees. The recombinant protein produced by C8-2 reacted specifically with sera of patients in the chronic phase of NANBH. The sequence of C8-2, 269 bp, did not hybridized with any human or chimpanzee genomic DNA, and had no homology with those of primates and viruses. The existence of this sequence in RNA of possibly infectious plasma was shown by RNA blot hybridization and by Southern blot analysis of products amplified by the polymerase chain reaction. These results strongly suggest that C8-2 is derived from the agent of this viral hepatitis.

A cDNA clone encoding a peptide highly specific for hepatitis C infection

A random primed lambda gt11-cDNA library was constructed from donors plasma presumably infected by blood-borne non-A, non-B hepatitis (hepatitis C:HC) agent and immunoscreened with serum pooled from patients with acute or chronic HC. Twelve lambda gt11-cDNA clones encoding antigens associated with HC infection in Japan as well as in the USA were isolated. Of these one clone consisting of 114 nucleotides and showing a discrete band on an immunoblot analysis, was extensively studied. The clone is not derived from the host DNA encoding one polypeptide specific and highly sensitive for serum from patients with HC and has no homology to the nucleotide sequences of known human viruses including hepatitis A,B and D viruses, Ebstein-Barr virus, coxsackievirus, immunodeficiency virus type 1 or Japanese encephalitis virus. These results suggest that this clone is derived from the genome of HC agent.