Evaluation of a new radioimmunoassay for detecting hepatitis B e antigen and its antibody

A new commercially available radioimmunoassay (RIA) (Abbott-HBe^TM) was used for determination of hepatitis B e-antigen (HBeAg) and its antibody (anti-HBe). Serial serum samples from 20 transiently HBsAg-positive patients with acute hepatitis were tested. In nearly all patients HBeAg could be shown for a short period with subsequent development of antiHBe. From 24 chronic HBsAg carriers serial serum samples collected during several years were tested. In 18 of 19 initially HBeAg-positive patients the HBeAg was lost after 6 months to 6 years; in 14 anti-HBe developed. A correlation was seen between the seroconversion and normalization of elevated alanine transferase levels. From another 22 chronic HBsAg carriers single serum samples were assayed. These samples were selected because neither HBeAg nor anti-HBe could be detected by the immunodiffusion (ID) technique. They had previously been examined for HBV-associated DNA-polymerase activity. In 20 patients HBeAg or anti-HBe could be detected by RIA. Those who were DNA-polymerase negative had anti-HBe, and 3 of 4 who were DNA-polymerase positive had HBeAg. When compared to earlier results by ID in these materials a higher frequency of HBeAg and, in particular, anti-HBe was detected by the RIA. By this test, HBeAg or anti-HBe was found in nearly all patients. The usefulness of HBeAg/anti-HBe in the evaluation of infectivity and prognosis in hepatitis B has been limited by the low sensitivity of the earlier test systems. Thus, this new RIA is a valuable addition to the diagnostic tests for patients with hepatitis B.     

Physicochemical heterogeneity of hepatitis B e antigen detected in asymptomatic carriers and carriers in a hemodialysis unit.

Physicochemical studies of hepatitis B e antigen (HBeAg) revealed a clear cut difference between e1 and e2 antigen. The e1 antigen was found to have a MW of Ca 150,000 and a pI of 6.4-7.2, whereas both the MW and pI of the e2 antigen were heterogeneous depending upon the source of serum. Sera obtained from asymptomatic carriers were characterized by low titers of HBs antigen, HBc antigen and DNA polymerase and contained e2 antigen of larger molecular weight (200,000-300,000) with a narrow distribution range and a pI of 4.8 to 5.2 (type 1). On the other hand, the sera from patients in a hemodialysis unit who were HBs antigen carriers and had high titers of HBs antigen, HBc antigen and DNA polymerase contained e2 antigen of heterogeneous distribution in MW (from 300,000 to 70,000) and pI (type 2 and 3). The e2 antigen obtained from the higher MW type 3 serum had lower isoelectric points (pI 4.5 to 5.2) as was the case with e2 antigen obtained from asymptomatic carriers whereas relatively wide range of isoelectric points (pI 5.1 to 8.2) was found with the lower molecular weight e2 antigen.     

乙型肝炎病毒e抗原基因作为酵母双杂交体系结合域载体的构建及表达

目的　以乙型肝炎病毒e抗原 (HBeAg)全基因为外源片段 ,构建酵母双杂交体系中结合域载体 ,研究其在酵母细胞中的表达 ,排除自身激活作用及毒性作用 ,验证其适用性。方法　根据报道序列设计、合成HBeAg全基因巢式引物 ,取患者血清 ,通过PCR方法分离HBeAg全基因片段 ,克隆入T载体 ,酶切鉴定及序列测定后 ,克隆入酵母双杂交体系结合域载体pGBKT7,构建pGBKT7 eAg载体。再次酶切鉴定阳性克隆后转入酵母 ,验证毒性作用 ;通过Western blot实验证实外源基因在酵母中的表达 ;并进一步验证自身激活作用。结果　由血清中分离的及 2次酶切鉴定的片段大小分别为 6 5 7bp和 6 39bp ,与预期大小一致 ;序列测定与报道的HBV分离株核酸及氨基酸同源性分别为96 %和 10 0 % ;转人酵母后无毒性及自身激活作用 ;Western blot实验出现阳性与预期大小 (2 4 .3× 10 3)一致的条带。结论　pGBKT7 eAg载体在酵母细胞中表达出融合蛋白 ,进一步验证无自身激活及毒性作用 ,此载体构建成功 ,适用于酵母双杂交体系。     

Nucleotide mutations associated with hepatitis B e antigen negativity

One hundred and forty four patients with chronic hepatitis B were tested to identify new mutations associated with hepatitis B e antigen (HBeAg) negativity, using a full genome sequence analysis. All the patients were Chinese and had hepatitis B virus infection of genotype C. Patients with none of the pre-core or core promoter mutations were significantly (P < 0.001) less common in the group with anti-HBe (13%) than in the group with HBeAg (56%). The complete nucleotide sequence was determined in four anti-HBe-positive patients who had neither pre-core nor core promoter mutations and in five HBeAg-positive patients who also had neither of these mutations (the groups were matched for age and sex). Six mutations were found to be significantly more common in the former group than in the latter: G529A (3/4 vs. 0/5), C934A (4/4 vs. 1/5), A1053G (4/4 vs. 1/5), G1915T/A (4/4 vs. 0/5), T2005C/A (4/4 vs. 0/5), and C3026T (3/4 vs. 0/5). Three of the six mutations were significantly more common in the four anti-HBe-positive patients who had neither pre-core nor core promoter mutations, compared to 11 HBeAg-positive patients who had pre-core and core promoter mutations, and also compared to 15 anti-HBe-positive patients who had pre-core and core promoter mutations, suggesting further the specificity of these mutations. Of the six mutations, two resulted in amino acid substitution in the polymerase protein, and one is located near the enhancer I region. The results suggest that the six newly discovered mutations are associated with HBeAg negativity.     

Hepatitis b e antigen and antibody: detection by radioimmunoassay in chimpanzees during experimental hepatitis b

Hepatitis B e antigen (HBeAg) and its antibody (anti-HBe) were evaluated using a sensitive radioimmunoassay (RIA) in weekly serum samples obtained from nine chimpanzees experimentally infected with hepatitis B virus (HBV). In two chimpanzees with HBV infection with detectable hepatitis B surface antigen (HBsAg) for less than five weeks, and in one chimpanzee with documented HBV infection with no detectable HBsAg, HBeAg was not detected; in all three, anti-HBe became detectable early in the infection. In six chimpanzees in which HBsAg was detected for 16 weeks or longer, HBeAg was detected early in the infection; in five, anti-HBe became detectable and HBeAg unde-tectable prior to the clearance of HBsAg. The sixth remained HBsAg-positive and HBeAg-positive for more than two years and never developed anti-HBe. These results confirm the sensitivity of this RIA and its value in predicting the course of HBV infections.     

The separation and analysis of hepatitis B e antigen.

A solid-phase radioimmunoassay has been used successfully for detecting hepatitis B e antigen in fractionated hepatitis B virus-containing serum. Ammonium sulphate precipitation followed by gel filtration through a column of Sepharose CL-6B resulted in two fractions of antigen-containing material with molecular weights of 220,000 and 130,000. The smaller of these two fractions was found to possess an average isoelectric point of 4.9 and consisted of two major polypeptide species with estimated molecular weights of 66,000 and 17,000 respectively. Affinity chromatography on Blue Sepharose showed that e antigen was not retained under conditions which bound serum albumin. These results are discussed in relation to the immunopathogenesis of hepatitis B.     

Immunoelectron microscopic localization of membrane attack complex and hepatitis B e antigen in membranous nephropathy

Summary Immunoelectron microscopy was used to localize membrane attack complex (MAC) and hepatitis B e (HBe) antigen in renal tissue specimens from a total of 9 patients with membranous nephropathy (MN); 6 with MN associated with a hepatitis B virus (HBV) infection, 2 with idiopathic MN, and 1 with lupus nephritis. All the patients were proteinuric, and 2 patients were classified as stage I-II, 6 as stage II, and 1 as stage IV. MAC, along with IgG and C3, was distributed within the subepithelial electron dense deposits in all the stages. MAC was also stained in the striated membranous structures within the glomerular basement membrane and mesangial matrix of some patients. In HBV-associated MN, HBe antigen was localized in the subepithelial electron dense deposits of 5 patients, while it was absent from the subepithelial deposits in a patient that was sero-positive for hepatitis B s antigen but negative for HBe antigen. This patient also lacked MAC deposition in these loci. These results suggest that MAC is associated with the formation of subepithelial deposits and proteinuria in MN. In HBV-associated MN, HBe antigen-antibody immune complex makes up the subepithelial deposits and is likely to activate the terminal components of complementin situ.     

Cryptic association of e antigen with different morphologic forms of hepatitis B surface antigen

When highly purified HBsAg particles, separated by rate zonal centrifugation into populations differing in predominant size, were tested for HBeAg, the e1 specificity was detected preferentially in association with particle fractions containing large filaments and Dane particles. These results were obtained both by agar gel diffusion and by radioimmunoassay for e antigen. The e antigen activity present in these fractions was potentiated by prior treatment of particles with Tween 80, suggesting cryptic localization of e1 specificity within or under the outer membrane. The HBeAg released by detergent treatment from a purified preparation composed predominantly of small-particle forms of HBsAg was separated by electrofocusing into a peak of nonparticulate e antigen in the pH range of 5.7--6.0. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed three major polypeptides in this preparation with approximate molecular weights of 25,000, 55,000, and 70,000. Furthermore, two additional peaks of e antigen activity were detected which migrated in association with HBsAg particles at isoelectric points of 4.4 and 5.5--5.6. The major portion of e antigen remained in association with particles after further purification by rate zonal centrifugation.     

Use of the cross-reactivity with hepatitis B virus antigens and antibodies for the demonstration of a woodchuck hepatitis virus ‘e’ antigen-antibody system

Woodchuck hepatitis virus (WHV)- associated antigens and antibodies were studied using current sensitive radio- or enzyme immunoassays (RIA, EIA). A significant cross-reactivity was observed between hepatitis B surface antigen (HBsAg) and woodchuck hepatitis surface antigen (WHsAg) using RIA or EIA (Abbott Laboratories, North Chicago, III., U.S.A.) although not with two other commercial EIA tested (Organon Technika, Oss, The Netherlands; Behringwerke AG, Marburg, F.R.G.).A weak but significant reactivity was also found when woodchuck sera positive for WHsAg or anti-WHs by immunodiffusion were tested for HBeAg and anti-HBe by RIA, suggesting the existence of a WHeAganti-WHe system in infected woodchucks. The specificity of this e-anti-e reactivity in the woodchuck was further confirmed by successful absorption experiments.WHsAg and WHeAg could be distinguished serologically by immunodiffusion and separated from each other by ultracentrifugation and ammonium sulphate precipitation. A WHeAg preparation was used to boost the presumed natural antibody activity of an immune woodchuck. The specific anti-HBe response detected by RIA during the immunization experiments demonstrated the existence of a soluble WHeAg cross-reacting with the human HBe-anti-HBe system. This was confirmed in immunodiffusion by a partial identity between the precipitin lines formed by the WHeAg-anti-WHe and HBeAg-anti-HBe reaction.Whether the WHe-Ag-anti-WHe system will mimick HBeAg and anti-HBe in all their clinico-pathological correlations, deserves further study.     

Isolation and characterization of liver-derived hepatitis B e antigen

Two subpopulations of hepatitis B e antigen (HBeAg) were isolated from a human liver infected with hepatitis B virus. HBeAg extracted from liver homogenate subsequent to treatment with buffered 3 M NaSCN or 0.5 M MgCl2 banded at the density of 1.13 g/cm3 in CsCl and was polydispersed on gel filtration. In contrast, HBeAg released with phosphate-buffered saline (PBS) was detected mainly at a density of 1.20 g/cm3 in a CsCl gradient and consisted of low molecular weight species on gel chromatography. Polypeptides of 40,000 and 45,000 daltons were found in NaSCN and PBS-released HBeAg preparations, respectively. The results are interpreted as suggestive that liver HBeAg is a dimer of the major core particle polypeptide in different physicochemical forms.     

Hepatitis B virus genotypes and spontaneous hepatitis B e antigen seroconversion in Taiwanese hepatitis B carriers

Hepatitis B virus (HBV) is classified into eight genotypes (A-H), and genotype C is associated with more aggressive liver disease compared to genotype B. However, the mechanisms responsible for the clinical differences remain unclear. To test whether genotype C patients had with lower rates of spontaneous hepatitis B ge antigen (HBeAg) seroconversion than genotype B patients, stored serum samples from 146 Taiwanese adult HBeAg-positive hepatitis B carriers followed-up for a mean of 52 months (range, 12-120 months) were tested for HBV genotype by a molecular method. Genotype C patients were significantly older than genotype B patients (mean age, 37 +/- 12 vs. 29 +/- 10 years, P < 0.001). During the follow-up period, genotype C patients had a significantly lower rate of spontaneous HBeAg seroconversion than genotype B patients (27 vs. 47%, P < 0.025). Spontaneous HBeAg seroconversion occurred one decade later in genotype C patients compared with genotype B patients. Multivariate analyses identified age < or =35 years (odds ratio: 2.08; 95% confidence interval [CI], 1.07-4.0; P < 0.05), high baseline serum alanine aminotransferase level (odds ratio: 2.34; 95%CI, 1.39-4.09; P < 0.005), and HBV genotype B (odds ratio: 1.94; 95%CI, 1.03-3.63; P < 0.05) as independent factors associated with spontaneous HBeAg seroconversion. In conclusion, genotype C patients, compared to genotype B patients, have a delayed HBeAg seroconversion in the immune clearance phase of chronic HBV infection, which may contribute to a more progressive liver disease and more refractory to antiviral therapy.     

A novel assay for hepatitis B e markers

The evaluation of a novel assay that allows simultaneous testing for hepatitis B e antigen and its antibody in a single well is described. The results of routine application and sequential studies on patients with acute hepatitis B and chronic hepatitis B treated with interferon are presented. The specificity and sensitivity of the assay and its ability to be used to follow the response of a patient during the whole seroconversion episode has been evaluated. The assay proved to give useful information about the reactivity of the sample, especially in those patients who were changing their “e” status. J. Med. Virol. 52:280–285, 1997. © 1997 Wiley-Liss, Inc.     

乙型肝炎病毒e抗原的纯化及其在人血清抗体检测中的应用

目的方法利用ＺｈｏｕＪｉａｎ教授提供的重组质粒ＤＮＡｐＢＶ２２０／ｅＡｇ，转染ＤＨ５α细胞，经３０℃培养３小时，４２℃培养６小时温度诱导后，提取乙型肝炎病毒ｅ抗原（ＨＢｅＡｇ）。经ＤＥＡＥ－ＳｅｐｈａｒｏｓｅＦａｓｔＦｌｏｗ层折纯化后免疫打点分析，收集阳性蛋白。经ＳＤＳ－ＰＡＧＥ电泳，考马斯亮蓝Ｇ２５０染色，显示为单一的蛋白带，用免疫印迹法（Ｗｅｓｔｅｒｎｂｌｏｔ）和免疫打点（ｌｍｍｕｎｏｄｏｔ）法，确定表达产物的特异性。将纯化的ＨＧｅＡｇ用酶联免疫吸附试验（ＥＬＩＳＡ）和免疫条。方法基检测人血清中的相关抗体。结果经４９例乙型肝炎病毒ｅ抗体（ＨＢｅＡｂ）阳性病人血清检验证实了其特异性。结论免疫条方法较ＥＬＩＳＡ方法更敏感、特异。     

Gender disparity in distribution of the major hydrophilic region variants of hepatitis B virus genotype C according to hepatitis B e antigen serostatus

Hepatitis B virus (HBV) e antigen (HBeAg) seroconversion during chronic HBV infection is known to play an important role in disease progression and patient response to antiviral agents. The aim of the present study was to analyze gender disparity in distribution of major hydrophilic region (MHR) variants according to HBeAg serostatus. Prevalence of MHR variants from 68 Korean patients with chronic hepatitis (31 HBeAg-positive and 37 HBeAg-negative) was examined in terms of HBeAg serostatus and sex by direct sequencing analysis of the MHR. Gender disparity was observed in the distribution of MHR variants according to HBeAg serostatus. In male patients, the prevalence of MHR variants was significantly higher in HBeAg negative patients than in HBeAg positive patients [58.8% (10/17 patients) vs. 14.3% (3/21 patients), P=0.004]. However, the same was not true in female patients [55.0% (11/20 patients) vs. 60.0% (6/10 patients), P=1.000)]. In addition, 2 mutation types (L110I and G145A) related to HBeAg serostatus were found. In conclusion, HBeAg seroconversion in male chronic patients infected with genotype C could lead to mutations of MHR, major target to host immune response, which might in turn contribute to HBV persistence and immune evasion.     

Solid-phase radioimmunoassay for hepatitis be antigen (HBeAg)

Summary A solid-phase radioimmunoassay was developed for the detection of HBeAg and anti-HBe in sera or serum fractions. HBe/sAg positive sera, partially purified HBeAg, partially purified HBsAg, and HBe/sAg negative sera were polymerized in polyacrylamide and compared for their ability to bind¹²⁵I-IgG (anti-HBe). Only gels containing HBeAg reacted specifically with the iodinated antibody. The specificity of the binding was confirmed by blocking and inhibition tests using anti-HBe, HBeAg, HBsAg, and negative control sera. The radioimmunoassay allows the specific and quantitative detection of HBeAg and anti-HBe even in the presence of detergents and high salt concentrations.

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Abbreviations HBsAg hepatitis B surface antigen - HBeAg hepatitis Be antigen - HBe/sAg hepatitis Be antigen and surface antigen - anti-HBe antibody to hepatitis Be antigen     

Hepatitis B virus pre-genomic RNA and hepatitis B core-related antigen reductions at week 4 predict favourable hepatitis B surface antigen response upon long-term nucleos(t)ide analogue in chronic hepatitis B

Background/AimsWe investigated the dynamics of serum HBV pre-genomic RNA (pgRNA) and hepatitis B core-related antigen (HBcrAg) in patients receiving nucleos(t)ide analogues (NAs) and their predictability for favourable suppression of serum hepatitis B surface antigen (HBsAg).MethodsSerum viral biomarkers were measured at baseline, weeks 4, 12, 24, 36, and 48 of treatment. Patients were followed up thereafter and serum HBsAg level was measured at end of follow-up (EOFU). Favourable HBsAg response (FHR) was defined as ≤100 IU/mL or HBsAg seroclearance upon EOFU.ResultsTwenty-eight hepatitis B e antigen (HBeAg)-positive and 36 HBeAg-negative patients (median, 38.2 years old; 71.9% male) were recruited with median follow-up duration of 17.1 years (interquartile range, 12.8–18.2). For the entire cohort, 22/64 (34.4%) achieved FHR. For HBeAg-positive patients, serum HBV pgRNA decline at week 4 was significantly greater for patients with FHR compared to non-FHR (5.49 vs. 4.32 log copies/mL, respectively; P=0.016). The area under the receiver-operating-characteristic curve (AUROC) for week 4 HBV pgRNA reduction to predict FHR in HBeAg-positive patients was 0.825 (95% confidence interval [CI], 0.661–0.989). For HBeAg-negative patients, instead of increase in serum HBcrAg in non-FHR patients, FHR patients had median reduction in HBcrAg at week 4 (increment of 1.75 vs. reduction of 2.98 log U/mL; P=0.023). The AUROC for week 4 change of HBcrAg to predict FHR in HBeAg-negative patients was 0.789 (95% CI, 0.596–0.982).ConclusionsEarly on-treatment changes of serum HBV pgRNA and HBcrAg at 4 weeks predict HBsAg seroclearance or ≤100 IU/mL in NA-treated CHB patients upon long-term FU.     

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)     

Hepatitis B core antigen (HBcAg) in serum of patients with chronic hepatitis B detected by a modified radioimmunoassay

Serum hepatitis B core antigen (HBcAg) was investigated in 85 patients with chronic hepatitis B virus (HBV) infection using a modified radioimmunoassay technique, based on high molarity treatment of samples to avoid masking of the antigen by the excess homologous antibody. Eighty-eight percent of HBeAg-positive cases and 19% of anti-HBe-positive cases were HBcAg positive in serum, with a positive correlation with the presence of HBcAg in the liver. Although the sensitivity of the method for the presence of complete virions was not absolute, as shown by the comparison with serum HBV-DNA testing, this technique may be helpful for assessing virus synthesis in patients with HBV infection.     

Detection of both hepatitis B e antigen and antibody in a single assay using monoclonal reagents

Monoclonal antibodies raised against HBeAg were used to develop a HBeAg and anti-HBe detection assay. Monoclones containing anti-HBe were used both for the coating of the solid phase and for the fluid phase label in a sandwich type assay. The percentage binding of 125I-labelled anti-HBe to serum HBeAg was much greater than that seen in a similar assay using only polyclonal reagents. Therefore it was possible to add a small quantity of HBeAg for neutralising any anti-HBe present in a test serum without affecting HBeAg detection. This small amount of serum HBeAg was incorporated into each test sample thus allowing the determination of the e status of a patient using only one aliquot of test serum. This single test assay could be performed either as a radioimmunoassay or as an ELISA. The sensitivity of these assays was found to be greater than the conventional polyclonal assay particularly with regard to sera containing anti-HBe.