Monoclonal antibodies to hepatitis B surface antigen (HBsAg) with anti-alpha specificity recognize a synthetic peptide analogue (S135-155) with unmodified lysine (141)

A synthetic peptide corresponding to residues 135-155 (S135-155) of the major protein component of HBsAg was conjugated to beta-galactosidase. This conjugate reacted with monoclonal anti-HBs antibodies having anti-alpha group specificity. The reaction was inhibited by: HBsAg of either subtype ad or ay; by unconjugated S135-155 or a shorter peptide S140-155, but not by unrelated peptides. Modification of lysine residues of either HBsAg or S135-155 reduced this inhibitory effect. These results indicate that Lys 141 is essential for maintaining the antigenicity of one of the epitopes responsible for the common alpha specificity of HBsAg and that studies involving the use of synthetic peptides and modifications of distinct amino acid residues in the native protein or in the peptide may help in characterizing epitopes of viral antigens in general.     

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.     

Characterization of minor and major antigenic regions within the hepatitis B virus nucleocapsid

Hepatitis B core antibodies (anti-HBc) appear very early during the course of the hepatitis B virus infection and often persist years after viral clearance. In order to characterize the immunodominant domain of the HBcAg, the human immune response against the HBV nucleocapsid (HBcAg) was analyzed by using 14 synthetic peptides. Anti-HBc antibodies were detected by an indirect enzyme-linked immunosorbent assay (ELISA) with HBc peptides. Results suggest that the anti-HBc response is heterogeneous and directed against the whole primary structure of the HBc protein. Results also indicate that the epitopes recognized by anti-HBc antibodies can vary with the stages of the disease. In most sera from patients with serological evidence of acute HBV infection, anti-HBc antibodies recognized all the HBc peptides; conversely, after the acute phase, anti-HBc antibodies recognized predominantly epitopes located within the central region of the HBc protein from residue 74 to 123. Our results suggest that the HBV core protein is made up of two antigenic regions: a major one expressing a family of immunodominant epitopes from residue 74 to 123, whereas the minor encompasses the rest of the protein. The concept of the conformational nature of the unique HBcAg determinant is discussed, suggesting numerous families of linear epitopes.     

Differentiation of core gene products of the hepatitis B virus in infected liver tissue using monoclonal antibodies

Hepatitis B virus (HBV) core gene translational products were localised previously in the cytoplasm and/or in the nuclei of infected cells. We investigated in naturally infected human hepatocytes whether this variation in the subcellular expression is due to differences in the presence of assembled core particles and other core gene derived proteins, the expression of HBeAg and the processing of liver tissue. By immunostaining of liver specimens infected with HBeAg-positive and HBeAg-minus variants of HBV, using monoclonal antibodies specific for assembled core particles and for various epitopes on denatured core protein, it was shown that virtually all immunoreactive core gene products are assembled into core particles. The latter are present both in the nuclei and in the cytoplasm of hepatocytes, independent of the infecting virus strain. A marked reduction or absence of immunoreactivity, observed with some monoclonal antibodies, was shown to result from nucleotide sequence variations within or close to the corresponding epitope. These results demonstrate that immunoreactive products, derived from the HBV core gene, in the nuclei and cytoplasm of human hepatocytes represent assembled core particles and that monoclonal antibodies with known recognition sites can reveal region-specific core gene variation of the infecting HBV population. J. Med. Virol. 53:127–138, 1997. © 1997 Wiley-Liss, Inc.     

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.     

Association of concurrent hepatitis B surface antigen and antibody to hepatitis B surface antigen with hepatocellular carcinoma in chronic hepatitis B virus infection

Antibody to hepatitis B surface antigen (HBsAg) (anti‐HBs) can exist in patients with chronic hepatitis B virus (HBV) infection. To date, little is known about the association of concurrent HBsAg and anti‐HBs (concurrent HBsAg/ anti‐HBs) with hepatocellular carcinoma (HCC). The aim of this study was to investigate the clinical relevance of concurrent HBsAg/anti‐HBs with preS deletion mutations and HCC in chronic HBV infection. A total of 755 patients with chronic HBV infection were included consecutively at a tertiary center. Logistic regression analysis was used to identify risk factors for HCC, and serum HBV DNA was amplified, followed by direct sequencing to detect preS deletions. The prevalence of concurrent HBsAg/anti‐HBs was 6.4% (48/755) and all HBVs tested were genotype C. HCC occurred more frequently in the concurrent HBsAg/anti‐HBs group than in the HBsAg only group [22.9% (11/48) vs. 7.9% (56/707), P = 0.002]. In multivariate analyses, age >40 years [odds ratio (OR), 14.712; 95% confidence interval (CI), 4.365–49.579; P < 0.001], male gender (OR 2.431; 95% CI, 1.226–4.820; P = 0.011), decompensated cirrhosis (OR, 3.642; 95% CI, 1.788–7.421; P < 0.001) and concurrent HBsAg/anti‐HBs (OR, 4.336; 95% CI, 1.956–9.613; P < 0.001) were associated independently with HCC. In molecular analysis, preS deletion mutations were more frequent in the concurrent HBsAg/anti‐HBs and HCC groups than in the HBsAg without HCC group (42.3% and 32.5% vs. 11.3%; P = 0.002 and 0.012, respectively). In conclusion, concurrent HBsAg/anti‐HBs is associated with preS deletion mutations and may be one of the risk factors for HCC in chronic HBV infection with genotype C. J. Med. Virol. 81:1531–1538, 2009. © 2009 Wiley‐Liss, Inc.     

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.     

The IgM antibody responses to the core antigen of hepatitis B virus

Little is known about the immunoglobulin class of antibodies to HBcAg. In the present study sera containing anti-HBc were fractionated by sucrose density-gradient centrifugation, and all serum fractions were tested against HBcAg by immunoelectro-osmophoresis. In addition selected fractions were examined by complement fixation test, immune adherence hemagglutination and immune electron microscopy. Anti-HBc activity in IgG serum fractions was demonstrated by all four techniques used, but HBcAg-specific IgM was detected only by immunoelectro-osmophoresis and by immune electron microscopy. In acute hepatitis B, HBcAg-specific IgM was detected for up to eight weeks after the onset of jaundice. It was also found transiently in two patients who developed chronic hepatitis B without an icteric episode and in one out of thirteen patients with HBsAg-positive chronic liver disease, but in none of eight healthy HBsAg carriers. The results suggested that HBc Agspecific IgM is formed transiently in response to primary HBV infection but is generally undetectable in established HBsAg carriers.     

Human monoclonal antibodies for the immunological characterization of a highly conserved protein domain of the hepatitis C virus glycoprotein E1.

Although both envelope glycoproteins of the hepatitis C virus, E1 and E2/NS1, show a high degree of sequence variation, the E1 protein includes a well conserved domain, which may be functionally important. We have analysed the human B cell response to a peptide fragment from amino acid residues 314-330 (EP3) covering the central conserved sequence of this domain. Anti-hepatitis C virus-positive blood donors were screened for anti-EP3 antibodies with an ELISA based on immobilized peptide. Thirty out of 92 (32%) RIBA-confirmed donors displayed a significant antibody response to EP3. From three of these blood donors we established four anti-EP3-producing heterohybridoma cell lines: Ul/F30 and Ul/F31 produced IgM-kappa, whereas Ul/F32 and Ul/F33 secreted the isotypes IgG1-lambda and IgG1-kappa, respectively. Epitope analysis with overlapping nonapeptides suggests the existence of different antigenic determinants within the EP3 fragment. Although both IgG antibodies Ul/F32 and Ul/F33 have dissociation constants to the peptide of approximately 10(-9) M, binding to recombinant E1 protein expressed in COS-7 cells was different. Only Ul/F33 detected envelope protein of approximately 24-35 kD in Western blot. This human MoAb will be useful for further investigations on the hepatitis C virus glycoprotein E1.     

Hepatitis B surface antigen (HBsAg) subtype-specific antibodies in persons vaccinated against hepatitis B

One hundred sixty-three persons immunised against hepatitis B with a vaccine containing HBsAg either of adw or ayw subtype were examined for antibodies against the a, d, and y determinants of HBsAg. Sera were tested for antibodies against HBsAg adw and HBsAg ayw separately by a solid-phase radioimmunoassay using polystyrene beads coated with HBsAg of either adw or ayw subtype, and the relative amounts of antibodies against the single determinants were calculated. After the third immunisation, all vaccinees had antibodies against the common determinant a. A quantitative evaluation showed that on average about 50% of HBsAg-specific antibodies were directed against the a determinant, and about 50% against d or y, respectively. However, as only anti-a is protective against cross-infection with other HBsAg subtypes, the degree of immunity of a person vaccinated against hepatitis B should be evaluated by the determination of antibodies to a rather than antibodies against total HBsAg.     

土拨鼠肝炎病毒核心蛋白的高效表达和B细胞表位鉴定

目的 建立高效表达土拨鼠肝炎病毒核心蛋白（WHcAg）的方法并对其B细胞表位进行鉴定。方法分别构建不同截短型WHcAg的质粒以了解能大量表达并形成WHV核心颗粒的区段，利用变性WHcAg制备单克隆抗体以寻找能与WHcAg线性B细胞表位结合的单克隆抗体。结果 WHcAg前144或149氨基酸残基能够大量表达并能形成颗粒样结构。这2种截短型WHcAg能够在大肠杆菌中表达并组装成直径为34肿的核心颗粒，最终纯化获得毫克级的核心蛋白。截短型WHcAg保留了全长WHcAg的抗原性，而且变性WHcAg存在另外的B细胞线性表位，利用变性WHcAg进行免疫制备单克隆抗体获得的5株抗体均针对WHcAg的N末端表位，该表位在WHcAg和HBcAg高度保守。结论 建立了高效表达WHcAg的方法，制备了针对WncAg单克隆抗体。并对WHcAg的线性B细胞表位进行了鉴定，发现WHcAg和HBcAg的N末端存在共同的线性B细胞表位。     

Two low molecular weight peptides as common determinants to different molecular forms and specificities of hepatitis b e antigen (hbeag)

Two fractions, I and II, corresponding to heavy and light molecular forms of HBeAg and respectively associated with the (HBe/1 + HBe/2) and (HBe/3) specificities, were separated by ammonium sulfate precipitation in HBeAg-positive chimpanzee plasma. I 125-labeling of fractions I and II and immune precipitation by anti-HBe and anti-Human IgG were followed by autoradiographic analysis after SDS polyacrylamide gel electrophoresis: This revealed that two small peptides (a major 17,000 MW and minor 21,000 MW) seem common to the various molecular forms and specificities of HBeAg. Both peptides were found tightly linked to IgG in fraction I, associated with HBe/1 and HBe/2 and precipitated by 1.33 M (NH₄)₂SO₄. In the HBe/3-positive fraction II these peptides seemed attached to IgG light chains only.     

筛选出一株可识别多种变异HBsAg的单克隆抗体及其应用

目的 制备筛选可识别变异表面抗原(hepatitis B surface antigen,HBsAg)的单克隆抗体(monoclonal antibody, mAb).用筛选出的单克隆抗体建立检测变异HBsAg的ELISA实验方法.方法 用血源HBsAg免疫Balb/c小鼠,通过杂交瘤细胞融合技术制备抗-HBs单克隆抗体.不同单克隆抗体包被酶标反应孔,检测真核细胞表达的野生及变异HBsAg,了解各种单克隆抗体的反应模式 .筛选出可以较好识别变异HBsAg的单克隆抗体Hb1,优化该抗体ELISA检测HBsAg的方法,与 8种HBs Ag检测试剂比较检测变异HBsAg的能力.结果 经过筛选,得到一种可以较好识别包括G145R在内大多数变异HBsAg的单克隆抗体.检测变异HBsAg的能力优于市售HBsAg 诊断试剂.结论 用本实验制备的单克隆抗体可以用于ELISA检测变异HBsAg,减少HBsAg变异株的漏检率.     

Major antigenic domain recognized by monoclonal antibodies maps within the carboxy-terminal moiety of a recombinant human immunodeficiency virus-1 p24 protein.

Antigenicity in mice of a recombinant polypeptide including the complete amino acid sequence of mature human immunodeficiency virus type 1 p24 protein was studied by induction of monoclonal antibodies (MAbs). A panel of nine recloned hybridomas secreting MAbs with anti-p24 reactivity was isolated and further characterized. Competitive inhibition experiments suggested that the MAbs could be grouped into four epitopic classes corresponding to at least two distinct determinants. Analysis of reactivity to recombinant p24 deletion variants indicated that all the recognized epitopes are localized within a carboxy-terminal domain (amino acids 168-208) which should be largely exposed in recombinant as well as authentic antigen. Lack of response to N-terminal and central portions of p24 suggests that the antigenicity of those regions in the natural polypeptide is strongly conformation-dependent.     

Development and validation of a model for hepatitis B e antigen seroconversion in entecavir-treated patients with chronic hepatitis B

Achieving hepatitis B e antigen (HBeAg) seroconversion is a satisfactory endpoint during antiviral treatment for chronic hepatitis B (CHB). This study aimed to develop and validate a novel scoring system to predict HBeAg seroconversion during entecavir (ETV) treatment. A total of 526 patients with HBeAg-positive CHB treated with ETV for at least 1 year were randomly assigned to the training and validation cohorts. Baseline parameters including hepatitis B virus DNA, hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBcAb), and alanine aminotransferase level were quantified. Patients who achieved HBeAg seroconversion were compared with those without HBeAg seroconversion. A prediction model was established to predict HBeAg seroconversion during ETV treatment. After a median follow up of 2.67 years, 93 (36.0%) and 87 (32.5%) patients in the training and validation cohorts developed HBeAg seroconversion. A prediction score composed of age, HBsAg and HBcAb quantification was derived. Areas under receiver operating characteristic curve at 5 years of this prediction score were 0.70 and 0.72 in the training and validation cohorts. By using the dual cutoff values of 0.28 and 0.58, the model was endowed with high sensitivity and specificity to exclude or identify patients developing HBeAg seroconversion (90.3% sensitivity and 90.2% specificity in the training cohort as well as 92.8% sensitivity and 84.4% specificity in the validation cohort, respectively). A novel prediction score that uses baseline clinical variables was developed and validated. The score accurately estimates the probabilities of developing HBeAg seroconversion at 5-years ETV therapy in patients with CHB.     

Prevalence of hepatitis B e antigen and its antibody as detected by radioimmunoassays

A solid-phase radioimmunoassay (RIA) for the detection of hepatitis B e antigen (HBeAg) and antibody (anti-HBe) was developed. The RIA was approximately 1,000-fold more sensitive than rheophoresis for HBeAg, and approximately 6,000-fold more sensitive than rheophoresis for anti-HBe. Generally, less than one-fifth of hepatitis B antigen (HBsAg)-positive sera from blood donors were positive for either HBeAg or anti-HBe by rheophoresis; in contrast, more than 90% of the samples were positive by the RIA method. The ratio of HBeAg to anti-HBe among HBsAg carriers varied in different geographic localities. Also, the presence of HBeAg correlated directly with the titer of HBsAg and the presence of Dane core particles. Anti-HBe was associated with lower titers of serum HBsAg.     

Quantitative of serum hepatitis B core antibody is a potential predictor of recurrence after interferon-induced hepatitis B surface antigen clearance

BackgroundRecurrence is common for patients with chronic hepatitis B (CHB) who achieved hepatitis B virus (HBV) surface antigen (HBsAg) clearance after antiviral treatment. The aim of the study is to explore the possibility of quantitative hepatitis B core antibody (Anti-HBc) level as a biomarker to predict recurrence.MethodsA total of 73 patients with HBsAg clearance were enrolled in this study, 16 cases with recurrence and 57 cases of non-recurrence. A newly developed double-sandwich Anti-HBc immunoassay was used to detect the quantitative Anti-HBc level before therapy (baseline) and at the end of therapy. Logistic regression analysis was used to evaluate the predictive ability of quantitative Anti-HBc levels for recurrence.ResultsQuantitative Anti-HBc levels at the end of therapy in both recurrence and non-recurrence groups were significantly lower than those of before therapy (P < 0.001). In addition, the declining trend of the recurrence group was significantly greater than that of the non-recurrence group (0.71 log10 vs. 0.45 log10 IU/mL, P = 0.026). Quantitative Anti-HBc levels in non-recurrence group were higher than those in recurrence group at baseline and drug withdrawal (P = 0.023, P < 0.001). Multivariable analysis showed that Anti-HBc level at drug withdrawal alone was associated with recurrence (OR = 0.116, P = 0.037). At Anti-HBc level >2.3386 log10 IU/mL, the predictive sensitivity and specificity for recurrence were 80.0% and 71.9%.ConclusionsQuantitative Anti-HBc level can be used as a potential predictor of recurrence after HBsAg clearance. Anti-HBc level at the drug withdrawal has better predictive value than the baseline.     

Non-A,non-b hepatitis virus: identification of a core antigen-antibody system that cross reacts with hepatitis b core antigen and antibody

Using immunodiffusion, a major cross-reactivity had been previously demonstrated between hepatitis B(HBe/3 Ag) and the antigen reported in the serum of non-A, non-B hepatitis patients, therefore redesignated NANBe Ag. By direct immunofluorescence a new antigen associated with, but distinct from, NANBe Ag has now been identified in the liver of 14/26 patients with NANB chronic active hepatitis. The homologous antibody was detected in the serum of these 14 patients. Behaving like HBc Ag and cross reacting with it by immunofluorescence, the new antigen was termed NANBc Ag. Anti NANBc also became detectable in serial acute phase and convalescence sera from 5/5 NANB Ag-positive posttransfusion hepatitis cases. Further characterization of NANBe and NANBc antigens achieved by fractionation of a NANB virus-infected liver showed NANBc Ag to be expressed on 22–25 nm HB core-like particles containing DNA polymerase activity. Cross-reactivity between NANBc and HBc antigens was confirmed by immunodiffusion. Liver-derived NANBe Ag identical to serum NANBe Ag exhibited the same physical properties as HBe/3 Ag and could be similarly released by disruption of the non-A, non-B virus cores. These results indicate that hepatitis B and NANB virions not only share the same structure and DNA polymerase activity but are also antigenically related and belong to the same new class of DNA viruses.     

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.