Cutoff levels of immunoglobulin M antibody against viral core antigen for differentiation of acute, chronic, and past hepatitis B virus infections

Problems in diagnosing viral hepatitis

The most reliable method of making a specific aetiological diagnosis of chronic viral hepatitis would be to identify virus specific cytotoxic T lymphocytes responsible for the killing of virus infected hepatocytes in each patient's liver. Unfortunately, this can not be proposed for routine diagnosis and surrogate tests are required. The detection of virus markers, and even of the virus itself, does not imply that liver damage is caused by virus infection. Indirect markers of the host's antiviral immunoresponse have to be used to confirm more specifically the diagnosis of viral hepatitis. IgM antibodies against viral antigens implicated in the elimination of the virus seem to be suitable alternative candidates. Significant changes in the serum values of viraemia and aminotransferases occur within a few days, while a significant variation in liver histology takes much longer. Only the kinetics of the highly variable parameters can be used for an appropriate study of the relationship between viraemia, antiviral immunoresponse, and liver cell necrosis. Quantitative and dynamic analyses of hepatitis virus markers seem the most suitable and reliable methods of monitoring the patients eligible for antiviral treatment and identifying the most appropriate time to start this.

Diagnostic markers of viral hepatitis B and C

Hepatitis B virus (HBV) serology has become extremely refined. As well as the recognised hepatitis B surface (HBs), hepatitis B core (HBc), and hepatitis B e (HBe) antigen-antibody systems, new markers have been introduced including pre-S1, pre-S2 for the envelope and the functional X protein. New automates have been introduced allowing flexibility in the different tests according to precise needs. The monitoring of pre-S1 antigen provides a relevant correlate of viral replication. The quantitative determination of HBV-DNA, pre-S1 Ag, and IgM anti-HBc seem most useful for the decision to use, and the monitoring of, antiviral treatment. Second generation ELISAs detect antibodies to three sets of hepatitis C virus (HCV) protein including the c22 core, and c33, and c100, which correspond to the non-structural regions (NS3 and NS4, respectively). Second generation ELISAs require confirmation by supplement assays, but their biggest limitation is the delayed appearance of anti-HCV after primary infection. In addition 10% of chronic infections with liver disease still remain seronegative despite circulating HCV RNA in serum or liver, or both. Much progress still has to be made before HCV serology can reach the level of sophistication of HBV.

Role of IgM antibody to hepatitis B core antigen in the diagnosis of hepatitis B exacerbations

IgM anti-HBc levels were measured by the IMx Core-M Abbott assay in 939 serum samples in order to define a specific and sensitive cut-off value for diagnosis of chronic hepatitis B. The sera used were obtained from 52 chronic HBV patients and 10 HBV carriers with HCV or HDV co-infections and 155 asymptomatic subjects without evidence of liver disease. A Youden index value of 95.4% with 98% sensitivity and 97.4% specificity was obtained for an IMx Index value of 0.204 as cut-off. A one-year follow-up study with monthly tests has shown that quantitative analysis of IgM anti-HBc can serve as a noninvasive tool for monitoring HBV infection, and provides an accurate diagnosis of hepatitis B exacerbations. Significant elevations of IgM anti-HBc levels were associated with hepatitis B exacerbations in 96.2% of the cases but with none of the ALT flare-ups observed in HCV or HDV infected individuals. These results suggest that quantitative analysis of IgM anti-HBc provides the highest degree of confidence in definition of spontaneous and therapy-induced exacerbations or remissions of hepatitis B.

Measurement of anti-HBc IgM levels using the Amerlite anti-HBc IgM assay

The Amerlite anti-HBc IgM assay was evaluated as a tool for determination of antibody levels. With an assay time of 1 hour, the test showed a broad dose response range with high sensitivity and specificity. The software configuration of the analyser can be customized to suit specific research requirements.

IgM antibody to hepatitis C virus in acute and chronic hepatitis C

To assess possible role of testing for IgM-specific antibody in the diagnosis and monitoring of patients with hepatitis C, we tested sera from 14 patients with acute and 97 patients with chronic non-A, non-B hepatitis for IgG and IgM antibody to hepatitis C virus. IgG antibody to hepatitis C virus was detected in 93% of acute cases and 91% of chronic cases. Of the 101 patients with IgG antibody to hepatitis C virus, 57% had IgM antibody to hepatitis C virus. None of the 20 healthy subjects or 40 patients with acute or chronic hepatitis A or hepatitis B had IgM antibody to hepatitis C virus. At the onset of clinical symptoms in acute hepatitis C, IgG antibody to hepatitis C virus was detected in 8 (57%) and IgM antibody to hepatitis C virus in 9 of 14 patients (64%). Eventually, both IgG and IgM antibody to hepatitis C virus became detectable in 13 of 14 patients with acute hepatitis C. Seven patients with antibody to hepatitis C virus resolved the acute infection within 6 mo and all seven cleared IgM antibody to hepatitis C virus, whereas two cleared IgG antibody to hepatitis C virus. Six patients had a chronic outcome of the acute infection and IgM antibody to hepatitis C virus persisted in detectable amounts for more than 6 mo in all (mean = 15.5 mo). Among 88 patients with chronic non-A, non-B hepatitis with IgG antibody to hepatitis C virus, IgM antibody to hepatitis C virus was detected in 45 (51%).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of viral proteins in circulating immune complexes from chronic carriers of hepatitis B virus

Sera from 54 children (mean age 5.8 years) with chronic hepatitis B virus (HBV) infection were investigated for the presence of immune complexes containing HBV proteins. Clinical diagnosis was established by histology and biochemical markers and included chronic persistent (36 cases) or chronic aggressive (seven) hepatitis, liver cirrhosis (six) and HBV-mediated membranous glomerulonephritis (five). Circulating immune complexes were precipitated with 2.5% polyethylene glycol and analysed by immune blot using monoclonal antibodies against S, pre-S2 glycopeptide, pre-S1 and HBe/c epitopes. All sera, including those from 11 healthy HBV-negative blood donors contained PEG-precipitable substances, but the amount of precipitate did not correlate with the presence or amount of HBV proteins. The great majority (36 out of 40) of HBeAg-positive patients contained HBs proteins in immune complexes, but no detectable HBe protein. The immune complexes usually contained more pre-S1 than the free HBsAg particles from the same patient. The precipitates of anti-HBe-positive patients rarely contained HBV proteins (two out of 14) and, if so, in low amounts. During follow up of six patients we found that high levels of HBs-containing immune complexes may be correlated with subsequent elimination of HBV. This elimination is possibly initiated by binding of anti-pre-S1 antibodies to HBV and HBs particles.

Glycosylated protein in lipofuscin

Images

Differential diagnosis of acute viral hepatitis using rapid, fully automated immunoassays

We report the development of three rapid, fully automated immunoassays allowing the differential diagnosis of acute viral hepatitis. These assays detect HBsAg, IgM antibody to hepatitis B core antigen (IgM anti-HBc) and IgM antibody to hepatitis A virus (IgM anti-HAV) using the IMx instrument system. All IMx assays were run in less than 45 minutes and all steps were fully automated including specimen dilution steps. Specimens from blood donors, diagnostic and hospital patients, and individuals with a variety of infectious and immune diseases were tested for IgM anti-HAV (n = 1473) or for IgM anti-HBc (n = 1606) or for HBsAg (n = 9700) by the IMx and commercially available EIA and RIA. Each IMx assay showed 99.8% agreement with current EIA. Reproducibility in all hepatitis IMx assays was significantly better than that observed with manual or semiautomated assays; within-run and between-run % CV ranged from 2.2 to 4.8 and 3.5 to 10.3 respectively. In 29 acute hepatitis B patients studied, HBsAg and IgM anti-HBc were detected in the first available patient bleed collected from 0 to 4 week from the onset of symptoms. IgM anti-HBc persisted at reactive levels in the IMx assay for 1 to 24 weeks (mean 12.1 +/- 5.3 weeks) after the patient presented with symptoms. In individuals exposed to hepatitis A, IgM anti-HAV was detectable by IMx by 40 days post exposure (average 33.5 days) and IgM had declined to unreactive levels in IMx for all patients by from 3 to 6 months post exposure. These data demonstrate the use of these rapid IMx assays for differentiation of acute hepatitis A and B.

Expression pattern of the hepatitis B virus genome in transfected mouse fibroblasts

Permanent mouse fibroblast LTK- cells were transfected with dimeric hepatitis B virus (HBV) DNA linked to the simian virus 40 (SV40) early promoter/enhancer. Many clones stably expressed high levels of polyadenylated RNAs encoding hepatitis B surface (HBs) proteins (2.1 kb), HBe protein (3.6 kb), and HBx protein (0.6 kb). Although a chimeric RNA (4.0 kb) probably starting from the SV40 promoter was also synthesized, transcription of viral RNAs was predominantly directed by HBV promoters and its terminator. In contrast to HBV-transfected liver cells, the fibroblasts expressed only pregenomic 3.6-kb transcripts starting 5' to, but not within, the precore sequence. Thus, no normal core protein could be synthesized, but the cells expressed and secreted HBe protein of heterogeneous size. Small and middle HBs proteins were strongly expressed, while large HBs protein was almost absent. HBx mRNA expression was more efficient in mouse fibroblasts than in human hepatoma cells and 18-kDa HBx protein was exclusively detected in purified nuclei. Expression of HBe, small and middle HBs, and HBx proteins apparently does not require hepatic factors. Underexpression of HBc mRNA and large HBs mRNA suggests that activity of their promoters depends on cell-type-specific transcription factors.

Replication of hepatitis B virus in transfected nonhepatic cells

Permanent murine fibroblasts (LTK-) were transfected with a dimer of hepatitis B virus (HBV) DNA and a neomycin resistance gene which were both linked to the simian virus 40 (SV40) early promoter/enhancer. One of the stably transfected clones, LTK4/36, which secreted HBsAg, HBeAg, and HBV DNA was further analyzed. It contained eight to nine copies of integrated HBV DNA per haploid genome and low amounts of episomal HBV DNA. The secreted viral DNA was covalently linked to protein and was associated with particles which had the characteristic density of natural virions from serum of human viremic carriers. The particles contained an endogenous DNA polymerase, small and middle surface proteins, but in contrast to natural virions very little core protein and large surface protein. Instead of core protein, they contained incompletely processed HBe protein which is colinear to core protein. The fibroblast-derived virions were less stable than virions from human carriers or from transfected hepatoma cells. After several days of storage, their DNA was only partially protected against DNase. Obviously, nonhepatic cells can express HBV-like particles, even if liver-dependent gene products like large surface protein and core protein are missing.

19S and 7-8S forms of IgM antibody to hepatitis B core antigen in acute icteric hepatitis superimposed on hepatitis B surface antigen carriage

The 19S and 7-8S forms of IgM antibody to hepatitis B core antigen (IgM anti-HBc) were separated by rate-zonal centrifugation from the serum of 20 Greek hepatitis B surface antigen (HBsAg) carriers with a superimposed acute icteric hepatitis positive for IgM anti-HBc by a radioimmunoassay. Serological markers of hepatitis A virus (HAV), hepatitis B virus (HBV) and hepatitis D virus (HDV) infections were detected with radioimmunoassays and serum HBV DNA was detected with molecular hybridization techniques. Eighteen of the 20 carriers showed a predominance of one or the other form of IgM anti-HBc. Low molecular weight (7-8S) IgM anti-HBc was observed more frequently in HDV superinfection (5/9) and was related to a low mortality (1/9). In contrast, 19S IgM anti-HBc was observed more frequently in reactivation of chronic hepatitis B (6/9) and was related to a high mortality (5/9). These preliminary data show that in HBsAg carriers with a superimposed acute icteric hepatitis, predominance of 19S IgM anti-HBc is frequently associated with a severe clinical course; the opposite is true for predominance of 7-8S IgM anti-HBc.

Assay of preS epitopes and preS1 antibody in hepatitis B virus carriers and immune persons

The diagnostical significance of the large hepatitis B surface protein with its preS1 attachment site and of anti-preS antibodies are not yet well known. We investigated the epitope of the preS1 attachment site to see whether it is a marker of viremia and whether antibodies against it occur in convalescents and vaccinees. For comparison, sera were also tested for the presence and relative amount of a preS2 epitope. The epitopes were detected by binding to specific monoclonal antibodies (mAb MA18/7 for the preS1 epitope and mAb Q19/10 for the preS2 epitope) at the solid phase of a sandwich enzyme-linked immunosorbent assay. Antibody against the preS1 epitope was detected by inhibition of binding to mAb MA18/7. This mAb inhibits attachment of preS1 antigen to hepatocytes and reacts with a subtype-independent sequential epitope at the surface of hepatitis B virus between amino acid 29-36. This preS1 epitope occurs in most hepatitis B surface antigen (HBsAg) carriers, irrespective of viremia. Free preS2 epitope Q19/10 is present in samples with more than 8 micrograms/ml total HBsAg and it is masked in sera with less HBsAg. Antibodies which compete with mAb MA18/7 for its viral preS1 epitope occur in one third of HBsAg carriers who were negative for hepatitis B e antigen. It also occurs in one third of convalescents and in most good responders to plasma-derived vaccines.

Comparison of class and subclass distribution of antibodies to the hepatitis B core and B e antigens in chronic hepatitis B

The IgG subclasses IgM and IgA1 of antibodies to hepatitis B core antigen (anti-HBc) and hepatitis B e antigen (anti-HBe) were assayed in sera from 82 patients with chronic hepatitis B utilising class/subclass-specific enzyme immunoassays (EIA). The solid-phase was either recombinant hepatitis B core antigen (rHBcAg) or rHBcAg converted to HBeAg by addition of 0.1% SDS with remaining HBcAg antigenicity blocked with monoclonal anti-HBc. Anti-HBc IgG1 was detected in 81 sera at a geometrical mean titre (GMT) of 296,110 x divided by 2.9. Anti-HBc IgG2 was not detected in any of the sera, and anti-HBc IgG3 and IgG4 were detected in 50 and 37 sera, respectively. Anti-HBc IgM and IgA1 were both significantly correlated to the presence of HBV DNA. The predominant antibody to HBeAg was found to be IgG1, being detected in 45 sera with a GMT of 1,035 x divided by 3.3. Anti-HBe IgG2 was not detected in any serum, while anti-HBe IgG3 and IgG4 were found in 8 and 23 sera, respectively. Anti-HBe IgG1, IgG3, and IgG4 were mainly detected in sera positive for anti-HBe in RIA (Abbott). No patient was found positive for anti-HBe IgA1 or IgM. Thus, in contrast to HBcAg, HBeAg does not trigger a persistent IgM and IgA1 response in chronic hepatitis B. The levels of anti-HBe IgG1 and IgG3 were much lower than the levels of anti-HBc IgG1 and IgG3. The presence of anti-HBe IgG4 was significantly correlated to that of anti-HBc IgG4.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulin isotypes of anti-HBc and anti-HBe and hepatitis B virus (HBV) DNA elimination in acute hepatitis B

Antibodies to hepatitis B core antigen (anti-HBc) and e antigen (anti-HBe) were assayed in 46 sera from ten patients with acute hepatitis B utilizing immunoglobulin class- and subclass-specific enzyme immunoassays (EIAs). The sera were sampled 1 to 512 days after onset of hepatic symptoms. Four patients cleared HBsAg rapidly, within 24 days, and six patients cleared HBsAg slowly, within 27-74 days after the onset of symptoms. In three of the patients with rapid clearance of HBsAg, hepatitis B virus (HBV) DNA was not detected in sera tested during the first week after onset. The fourth patient was not tested until 12 days after onset and was then found to be negative for HBV DNA. In four of the patients with slow clearance of HBsAg, HBV DNA was present during the first week of illness. In the other two patients, HBV DNA was not detected in the first serum, 11 and 17 days after the onset of illness. Anti-HBc IgM and IgA1 were detected in all patients, with maximum titers shortly after onset. Anti-HBc IgG1 was present in all sera tested. Anti-HBc IgG2 was not detected in any of the sera. Anti-HBc IgG3 and IgG4 were detected in all patient sera, with IgG3 paralleling IgG1, and IgG4 mainly in sera long after onset. Anti-HBe IgG1, IgG3, and IgG4 were detected in three, two, and two patients, respectively. Anti-HBe IgG2, IgM, IgA1, or IgA2 was not found in any patient. The time required for maximum titer of anti-HBc IgG1 was shorter in the patients with rapid clearance of HBsAg.(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of molecular biology in the diagnosis and management of viral hepatitis

In recent years molecular biology techniques allowed an extraordinary progress in knowledge of hepatitis viruses. New informations have accumulated on the mechanisms of virus replication and on the pathogenesis of liver damage. In the clinical setting, simple noninvasive methods that use the same technological approach provide a useful diagnostic tool for infections of hepatitis B virus (HBV) and hepatitis delta virus (HDV). Using these tests we may define whether a carrier of hepatitis B surface antigen has a liver damage due to HBV or HDV or to other, non-virological causes. Detection of HBV-DNA and HDV-RNA in serum and liver can also be used as a guide for prognosis and therapy.

IgG and IgM autoantiidiotype antibodies against antibody to HBsAg in chronic hepatitis B

Antibody directed against HBsAg carries idiotypic determinants that may induce an autoantiidiotype antibody response. We describe a solid-phase radioimmunoassay which allows specific detection of either IgG or IgM antibody to antibody directed against HBsAg. Among 138 chronic hepatitis B virus carriers, IgG autoantiidiotype was detected in 98 (71%) and IgM autoantiidiotype in 10 (80%). The autoantiidiotype reaction was blocked with antibody directed against HBsAg after removal of immune complexes by polyethylene glycol precipitation. The prevalence and levels of both classes of autoantiidiotype antibodies were highest in patients with hepatitis B virus DNA or HBeAg in serum. During follow-up, patients who lost hepatitis B virus DNA and HBeAg from serum had lower titers of autoantiidiotype and were less likely to have autoantiidiotype than patients who persisted in having hepatitis B virus DNA and HBeAg in serum. Thus, the presence and titer of autoantiidiotype correlated with serologic evidence of active viral replication in chronic hepatitis B. These findings suggest that the antibody directed against HBsAg response may play a role in modulating viral replication in chronic hepatitis B.

Frequent detection of antibodies to hepatitis B virus x-protein in acute, chronic and resolved infections

Recombinant MS2- or beta gal fusion proteins containing parts of hepatitis B virus (HBV) HBx-, HBc-, and HBs-amino acid sequences were expressed in Escherichia coli and were used to screen 96 and 60 serum samples of HBV infected and uninfected patients, respectively, for the corresponding antibodies by immunoblotting. Antibodies against HBx were detected in 20 out of 65 sera of patients with previous resolved HBV-infection, in 3 out of 7 patients with persistent infection, and in 9 out of 24 sera of patients with acute HBV infection. The specificity of the immune reaction was confirmed by competition experiments with MS2- and beta gal-HBx fusion proteins, and by the lack of HBx antibodies in the sera of uninfected patients. Hbs and HBc antibodies were detected less frequently by immunoblotting with recombinant fusion proteins than by a commercial immunoassay. Our results indicate that HBx antibodies are induced early and frequently during HBV infection suggesting that the HBx protein is an early antigenic protein expressed in vivo.

Hepatitis B serology--help in interpretation

This review discusses the serologic markers of hepatitis B virus (HBV) infection. Interpretation of various serologic profiles is provided, and the importance of maternal screening for interruption of perinatal transmission of HBV infection is stressed.

Anti-HBc IgM in cases of hepatocellular carcinoma and cirrhosis in Taiwan

The sera of apparently healthy carriers of hepatitis B virus surface antigen enrolled in the Taiwan Prospective Study were tested retrospectively for anti-HBc IgM, to determine whether this test would be useful in predicting the development of hepatocellular carcinoma (HCC) and/or cirrhosis. In comparison with men who did not develop HCC or cirrhosis, the relative risk of those with anti-HBc IgM elevations was 3.4 and 5.6, respectively. Each of these factors was highly statistically significant, although the difference between them was not. Demonstration of anti-HBc IgM titers of greater than 1:1000 in serum probably reflects ongoing low level viral replication but not recent infection. Anti-HBc IgM appears to be a useful prognostic indicator for the future development of HCC and/or cirrhosis.