Characterization of integrated hepatitis B viral DNA cloned from a human hepatoma and the hepatoma-derived cell line PLC/PRF/5.

Recombinant phage clones carrying integrated hepatitis B virus (HBV) DNA sequences have been isolated from two phage libraries made from human DNA of a hepatoma and a hepatoma-derived cell line. One clone from each library has been characterized both by restriction mapping and by electron microscopy. In one clone there is at least one complete and uninterrupted HBV genome, and in the other the HBV sequences are composed of two major subgenomic fragments inverted with respect to each other. The host-virus junctions are localized within the positions 1,700-2,600 base pairs on the physical map of the free viral genome. The pre-S/S (surface antigen gene) region is conserved between the two clones. The two clones do not have common cellular sequences nor do they contain cellular homologues to six retroviral oncogenes. For one clone, the hepatitis B surface antigen gene was found to be functional when introduced into mouse thymidine kinase-negative cells by transfection.     

High affinity monoclonal antibodies to hepatitis B surface antigen (HBsAg) produced by somatic cell hybrids

Somatic cell hybrids (hybridomas) have been established which produced antibodies to hepatitis B surface antigen (HBsAg) by immunizing BALB/c/mice with a highly purified preparation of HBsAg and fusing their splenocytes with the myeloma cell line P3-NSI/1-Ag4-1. The route of immunization, interval between primary and secondary immunizations, and immunizing antigen concentration appeared crucial for optimal establishment of the hybrid cell lines. From one cell fusion, described here in detail, we established 47 hybrid cell lines secreting antibody to HBsAg (anti-HBs). The resultant hybrids produced anti-HBs of sufficient affinity and concentration to yield values over 400 times background in a solid-phase radioimmunoassay. Three of the secreting hybrids have been cloned by dilutional techniques. The anti-HBs from such hybrids showed specificity for antigens present on HBsAg subtypes (adw and ayw). Monoclonal anti-HBs antibodies to various antigenic components of HBsAg may lead to refinement in the immunodiagnosis of hepatitis B infection and serve as potent probes in the characterization of this complex particle. Moreover, they offer the potential for the development of highly specific immunoprophylactic reagents.     

Preparation and characterization of human monoclonal antibodies directed against the hepatitis B virus surface antigen

The hepatitis B surface antigen (HBsAg) is highly immunogenic and induces an antibody response which is protective in vivo against hepatitis B virus (HBV) infection. Human monoclonal antibodies specific for HBsAg were produced, which could have potential therapeutic applications. Lymphocytes obtained from a vaccinated donor were stimulated in vitro and fused with the human myeloma cell line GM 4672, and eight hybridomas were obtained. Three of these clones, which reacted in an ELISA against the HBsAg vaccine, were expanded, subcloned and further analyzed. The subclones E7C2, C4C10, and D5B2 were able to bind to different HBsAg preparations, which express various subtypes, and recognized the major HBsAg peptides in Western blot analysis. Cross-inhibition experiments showed that E7C2, C4C10 and D5B2 are directed against the same epitope and have an affinity constant ranging from 5 X 10(7) to 3.3 X 10(9) M. Furthermore, these antibodies stained the surface and cytoplasm of the HBsAg-secreting cell lines PLC/PRF/5 and 4.10. The production of immunoglobulins varies from 0.3 to 1.3 micrograms/ml/10(6) and has remained stable over a period of 8 months. These human monoclonal antibodies, which appear to be directed against an antigenic determinant common to all HBsAg subtypes, could be useful in the study of HBV-related liver diseases as well as in their diagnosis and experimental therapy.     

Regulation of T-cell function by antibodies: enhancement of the response of human T-cell clones to hepatitis B surface antigen by antigen-specific monoclonal antibodies.

Eight mouse monoclonal antibodies specific for hepatitis B surface antigen (HBsAg) were examined for their effects on the antigen-induced proliferative response and lymphokine production of human HBsAg-specific T-cell clones in vitro. While all specifically enhanced the T-cell proliferative response, antibodies of the IgG class were generally more effective than those of the IgM class. Both the divalent F(ab')2 and the monovalent Fab fragments of an IgG monoclonal antibody had no effects, indicating that the Fc portion of the antibody molecules was required. Since antigen-presenting cells bear surface receptors for the Fc of IgGs and fewer or none for that of IgMs, the above results also suggest that antibodies enhance the capture of antigens by antigen-presenting cells as a result of the binding of antigen-antibody complexes to the Fc receptors on these cells. In addition to potentiating the proliferation of the T-cell clones, antibodies also increased the antigen-induced production of interferon-gamma by these cells. The present in vitro studies suggest that antibodies may regulate immune responses and do so by enhancing antigen presentation and thus augmenting antigen-induced activation and clonal expansion of T cells.     

Integrated hepatitis B virus DNA sequences specifying the major viral core polypeptide are methylated in PLC/PRF/5 cells.

The methylation of various hepatitis B virus (HBV) DNA sequences was examined using the restriction endonucleases Hpa II and Msp I. HBV DNA from virions (Dane particles) and virus-infected liver tissue was digested with Hpa II or Msp I and fractionated by electrophoresis in agarose gels, and the restriction enzyme cleavage pattern was examined by Southern blot analysis. No methylation of the 5' C-C-G-G 3' recognition sequence was detected in either virion DNA or HBV DNA from infected liver tissue. The tissue culture cell line PLC/PRF/5, derived from a human hepatoma, possesses HBV DNA exclusively integrated at several sites. Digestion of PLC/PRF/5 DNA with Hpa II and Msp I revealed that the integrated HBV DNA sequences were methylated. Further analysis using probes specific for various regions of the HBV genome showed that some of the hepatitis B viral DNA sequences, including those specifying the major surface antigen polypeptide, were methylated infrequently or not at all. In contrast, the viral DNA sequences coding for the major core polypeptide were extensively methylated. Because the surface antigen is expressed in these cells while the core antigen is not, our results suggest that DNA methylation could account for the selective expression of HBV genes in this hepatoma cell line.     

Serum hepatitis B surface antigen (HBsAg) kinetics in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B

Background

We investigated the differences in HBsAg kinetics at different levels of viremia in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB).

Methods

We compared HBsAg levels among HBeAg-negative CHB patients with persistently undetectable HBV DNA (≤20 IU/mL; Group A, n = 100), HBV DNA 20–2,000 IU/mL (Group B, n = 100), and HBV DNA >2,000 IU/mL (Group C, n = 100). HBsAg and HBV DNA levels were measured at three consecutive time points during follow-up (median 21.4 months).

Results

Median HBsAg levels were significantly lower in Group A than in Groups B and C at all time points (p < 0.001). HBV DNA and HBsAg levels were weakly correlated (r = 0.180 and 0.151 for Groups B and C, respectively). Among patients with HBsAg <100 IU/mL, Group A patients had the greatest median serum HBsAg reduction (0.341 log IU/mL/year; Group B, 0.122 log IU/mL/year; Group C, 0.057 log IU/mL/year; p = 0.002). Among Group A patients with HBsAg <100 IU/mL, baseline HBsAg achieved an AUROC of 0.876 in predicting >1 log annual HBsAg reduction; 10–100 IU/mL HBsAg was the optimal level for prediction (sensitivity 90 %; specificity 74.6 %). Serum HBsAg/HBV DNA ratios were significantly higher in Group B than in Groups A and C (p < 0.05).

Conclusions

HBV DNA and HBsAg were weakly correlated. Only patients with undetectable HBV DNA showed decline in HBsAg levels during follow-up. The greatest reduction in HBsAg levels occurred in patients with baseline HBsAg <100 IU/mL.     

Characterization of small hepatitis B surface antigen epitopes involved in binding to human annexin V

Previously, we have shown that small hepatitis B surface antigen (SHBsAg) binds specifically to human annexin V (hAV) and that hAV plays a key role in the initial steps of hepatitis B virus (HBV) infection. We have also demonstrated the spontaneous development of anti-idiotypic antibodies (antibodies to HBsAg Ab2) in rabbits immunized with hAV. As Ab2 is able to inhibit the binding of hAV to SHBsAg, Ab2 might contain epitope(s) mimicking a region of hAV for binding to SHBsAg. Identification of this epitope will therefore reveal a SHBsAg sequence involved in hAV binding. Using a panel of synthetic peptides covering the region of SHBsAg located on the outer surface of the virus, binding studies showed that the region incorporating amino acids (aa) 125–131 of SHBsAg is important for binding to Ab2 and consequently also for binding to hAV. Further experiments revealed that not only this region, but also the region incorporating aa 158–169, is involved in the binding of SHBsAg to hAV. As these regions are located in the structural vicinity according to the topological model of HBsAg proposed by Chen et al. , our findings suggest that these regions are parts of a conformational epitope of SHBsAg for binding to hAV. Because of the crucial role of hAV in HBV infection, further studies on the HBsAg epitopes for hAV binding may lead to the development of a new generation of vaccines or molecules for prevention and for treatment of patients with chronic hepatitis B.     

Clearance of hepatitis B surface antigen in chronic carriers of hepatitis delta antibodies.

BACKGROUND/AIMS: We evaluated the rate of seroclearance of the hepatitis B surface antigen (HBsAg) and its clinical significance in patients with chronic hepatitis delta virus (HDV). METHODS: Antibody to HDV was tested in HBsAg-positive subjects admitted to our Hospital from 1991 to 1995. In 1997, a biochemical and virologic study was performed in the surviving anti-HD-positive patients who had not undergone transplantation. As a control, a cohort of 106 HBsAg-positive, anti-HD-negative patients was studied. RESULTS: One hundred and forty-one subjects were originally positive for anti-HD. After 4 years of follow-up, six of the 60 patients who underwent re-evaluation (10%) had cleared the HBsAg: three of the six patients had minimal changes at the initial liver histology and normal ALT, whereas in the remaining three patients with chronic active hepatitis ALT normalized during the observation. Anti-HD persisted in five of the six patients. Only one patient had raised anti-HBs. In contrast, three of 106 HBsAg carriers without HDV infection (2.8%) cleared the HBsAg within the same time and seroconverted to anti-HBs (p=0.002). CONCLUSION: HBsAg clearance is increased over the years in HDV patients compared to ordinary HBsAg carriers, and is often associated with improvement of HDV disease without seroconversion to anti-HBs.     

Etiology of hepatitis B surface antigen (HBsAg)-negative chronic hepatitis.

A study was undertaken to elucidate the etiology of HBsAg-negative chronic hepatitis. Form 37 individuals with HBsAg-negative chronic hepatitis, 11 had liver membrane autoantibody (LMA) and were thus classified as autoimmune. 6 patients had anti-HBc, 1 of which was also positive for LMA. The majority of individuals with HBsAg-negative chronic hepatitis had antibodies to hepatitis A antigen (anti-HAV), in general at low titer. We conclude from our data that hepatitis A and hepatitis B virus infections are unlikely to play a significant role in inducing or maintaining HBs-Ag-negative chronic hepatitis. The etiological role of non-A non-B hepatitis agent(s) is difficult to estimate and must await the detection of appropriate markers for type non-A non-B hepatitis.     

Effect of transfusion of fresh-frozen plasma on recipients' antibodies to hepatitis B surface antigen and hepatitis B surface antigen status in countries where hepatitis B virus is endemic

BACKGROUND AND OBJECTIVES: Antibodies to hepatitis B virus (HBV) that are passively acquired through transfusions may lead to confusion and inappropriate clinical decisions. We evaluated the effects of transfusing fresh-frozen plasma (FFP) on serological tests for HBV antibodies in patients without such antibodies. MATERIALS AND METHODS: Tests for HBV surface antigen (HBsAg), and for antibodies to HBV surface antigen (anti-HBs) and HBV core antigen (anti-HBc), were carried out using enzyme immunoassay on the FFP and sera of 50 patients transfused with FFP containing anti-HBs. RESULTS: After FFP transfusion, the incidences of 'false' positivity for anti-HBs and anti-HBc were 64% (32/50) and 100% (seven of seven), respectively, and of 'false' negativity for HBsAg was 18.8% (three of 16) in previously positive patients. The post-transfusion seropositivity for antibodies results from passive transmission, whereas the inability to detect HBsAg is the result of decreased detectable levels. CONCLUSIONS: Laboratory staff and clinicians alike should be cautious in interpreting the results of the HBV marker tests in patients who have recently been transfused, and in obtaining specimens for such studies.     

Antibodies to hepatitis B core antigen in hepatitis B surface antigen-positive and -negative chronic hepatitis.

Antibody to hepatitis B core antigen (anti-HBc) is a sensitive indicator of hepatitis B virus (HBV) infection. However, anti-HBc has been found in only a few patients with chronic hepatitis. Therefore, we tested for anti-HBc in 124 sera from 67 patients with histologically proven chronic hepatitis by the indirect fluorescent antibody technique. All patients, except for one with chronic hepatitis who was seropositive for hepatitis B surface antigen (HBs Ag), had anti-HBc that persisted throughout the follow-up period (three months to three years). Of 33 HBs Ag-seronegative patients, anti-HBc was detected in seven patients and persisted for six months to two years. These findings suggest that in this study 21% of patients with chronic hepatitis with undetectable amounts of HBs Ag in the serum had evidence of recent or continued HBV replication.     

In vitro and in vivo tumour localisation with a monoclonal antibody directed against a membrane antigen on the human hepatocellular carcinoma cell line PLC/PRF/5

A monoclonal antibody, designated K-PLC1, has been produced to a tumour-associated antigen on the cell membrane of the PLC/PRF/5 cell line. Using an indirect immunofluorescence technique this antibody produced membrane staining of three hepatocellular carcinoma (HCC) cell lines and it has positively stained 10 of 11 human HCC biopsy specimens. In vitro, 125I-labelled K-PLC1 binds specifically to PLC/PRF/5 cells, as shown by competitive inhibition experiments. Tumours derived from the PLC/PRF/5 cell line were grown in nude mice and groups of tumour-bearing animals were injected with either [125I]K-PLC1 or [125I]mouse IgG, and then killed at 1, 4 or 7 days post injection. Bound radioactivity was counted in a variety of solid organs. Tumour:liver ratios for K-PLC1 were greater than those for mouse IgG at each time point, the differences being greatest on day 4 (ratio K-PLC1 4.4 +/- 0.93, ratio mouse IgG 1.53 +/- 0.60, mean +/- SD, P less than 0.05). The amount of [125I]K-PLC1 bound was greater in the tumour than in any other solid organ, the differences again being maximal on day four. Blood pool radioactivity however remained high throughout the study period. We conclude that anti-HCC monoclonal antibodies may be of value as immunodiagnostic and immunotherapeutic agents in human HCC.     

Production of human monoclonal IgG antibodies against Rhesus (D) antigen.

An Epstein-Barr virus (EBV)-transformed human B-cell line ( LB4r ) producing anti-Rhesus [Rho(D) antigen] antibody was fused with a non-immunoglobulin-producing mouse-human heteromyeloma ( SHM - D33 ) and selected in hypoxanthine/aminopterin/thymidine medium containing 0.5 microM ouabain. Surviving hybrids found to secrete specific anti-Rho(D) antibody were cloned by limiting dilution. Two clones (D4-B2 and E10-C1) producing high levels (12 and 20 micrograms/ml per 10(6) cells per 24 hr, respectively) of monospecific antibody (IgG3, lambda chain) were selected for expansion and further characterization. Compared to the parental cell line ( LB4r ), these hybridoma cell lines presented several advantages: antibody production was increased 10-fold, cloning efficiency was improved, and the EBV genome was not retained. Antibody production has been stable for greater than 8 months. These human monoclonal anti-Rho(D) antibodies have demonstrated utility in routine blood-group typing. They may also prove useful in the biochemical and genetic characterization of the Rh antigen system. Most important, they offer a source of Rh-immune globulin for the prevention of Rh immunization and alloimmune hemolytic disease of the newborn.     

针对HBV S基因发夹状siRNAs表达载体的构建及其在HepG2215细胞中对HBV基因表达的抑制作用

目的探讨通过载体在体外培养的细胞中表达发夹状siRNAs对HBV基因表达的抑制作用。方法构建表达针对HBV S基因mRNA的发夹状siRNAs的质粒pSilencer 2.1-U6-S,并与ayw亚型HBV全基因组表达质粒共转染体外培养的HepG2215细胞,用半定量RT-PCR分析目标mRNA表达丰度的变化,用ELISA法观察HBsAg表达的变化。结果siRNA处理组细胞上清中HbsAg和HBeAg含量分别比空白对照组降低了63.4%和68.0%,细胞中的2.1kb的信使RNA降低了75.2%。结论siRNA在体外培养的细胞中能有效地抑制HBV基因的表达。     

乙型肝炎免疫球蛋白聚氰基丙烯酸正丁酯纳米粒抑制HBsAg、HBV DNA分泌的体外实验

Objective To investigate the inhibitive activities of hepatitis B immunoglobulin(HBIG)poly(butylcynaoacrylate)nanoparticles(HBIG-PBCA-NP)to hepatitis B surface antigen(HBsAg)and hepatitis B virus(HBV)DNA secretions using HBV infected cell model in vitro.Methods HepG 2.2.15 cells were cultured with media containing HBIG-PBCA-NP or HBIG for several days,or cultured with HBIG-PBC-NP and HBIG for 2 days and without HBIG-PBCA-NP and HBIG from day 3.The supernatants at different time points were collected for quantitative detection of HBsAg and HBV DNA.The comparisons between groups were done by variance analysis.Resalts Secretions of HBsAg and HBV DNA in supernatants of HepG2.2.15 cultured with 0.1-10.0 IU/mL of HBIG-PBCA-NP and HBIG were inhibited significantly compared with control group.HBsAg titers and HBV DNA levels in supernatants of HBIG-PBCA-NP group and HBIG group cultured with media without HBIG-PBCA-NP and HBIG kept decreasing at day 5 and 7,then rebounded at day 9 and 11.HBsAg titera in supernatants of 0.1,1.0,5.0 IU/mL HBIG-PBCA-NP group were all significantly different from those in HBIG group at day 9[(31.31±1.98)μg/L vs(40.62±2.99)μg/L,(23.79±1.31)μg/L vs(36.51±2.12)μg/L,(19.91±1.74)μg/L vs(33.03±1.65)μg/L;F=412.24,P＜0.01].Couclusion HBIG-PBCA-NP can inhibit secretions of HgsAg and HBV DNA in vitro,which is more effective than HBIG.     

乙型肝炎免疫球蛋白聚氰基丙烯酸正丁酯纳米粒抑制HBsAg、HBV DNA分泌的体外实验

Objective To investigate the inhibitive activities of hepatitis B immunoglobulin(HBIG)poly(butylcynaoacrylate)nanoparticles(HBIG-PBCA-NP)to hepatitis B surface antigen(HBsAg)and hepatitis B virus(HBV)DNA secretions using HBV infected cell model in vitro.Methods HepG 2.2.15 cells were cultured with media containing HBIG-PBCA-NP or HBIG for several days,or cultured with HBIG-PBC-NP and HBIG for 2 days and without HBIG-PBCA-NP and HBIG from day 3.The supernatants at different time points were collected for quantitative detection of HBsAg and HBV DNA.The comparisons between groups were done by variance analysis.Resalts Secretions of HBsAg and HBV DNA in supernatants of HepG2.2.15 cultured with 0.1-10.0 IU/mL of HBIG-PBCA-NP and HBIG were inhibited significantly compared with control group.HBsAg titers and HBV DNA levels in supernatants of HBIG-PBCA-NP group and HBIG group cultured with media without HBIG-PBCA-NP and HBIG kept decreasing at day 5 and 7,then rebounded at day 9 and 11.HBsAg titera in supernatants of 0.1,1.0,5.0 IU/mL HBIG-PBCA-NP group were all significantly different from those in HBIG group at day 9[(31.31±1.98)μg/L vs(40.62±2.99)μg/L,(23.79±1.31)μg/L vs(36.51±2.12)μg/L,(19.91±1.74)μg/L vs(33.03±1.65)μg/L;F=412.24,P＜0.01].Couclusion HBIG-PBCA-NP can inhibit secretions of HgsAg and HBV DNA in vitro,which is more effective than HBIG.     

乙型肝炎免疫球蛋白聚氰基丙烯酸正丁酯纳米粒抑制HBsAg、HBV DNA分泌的体外实验

Objective To investigate the inhibitive activities of hepatitis B immunoglobulin(HBIG)poly(butylcynaoacrylate)nanoparticles(HBIG-PBCA-NP)to hepatitis B surface antigen(HBsAg)and hepatitis B virus(HBV)DNA secretions using HBV infected cell model in vitro.Methods HepG 2.2.15 cells were cultured with media containing HBIG-PBCA-NP or HBIG for several days,or cultured with HBIG-PBC-NP and HBIG for 2 days and without HBIG-PBCA-NP and HBIG from day 3.The supernatants at different time points were collected for quantitative detection of HBsAg and HBV DNA.The comparisons between groups were done by variance analysis.Resalts Secretions of HBsAg and HBV DNA in supernatants of HepG2.2.15 cultured with 0.1-10.0 IU/mL of HBIG-PBCA-NP and HBIG were inhibited significantly compared with control group.HBsAg titers and HBV DNA levels in supernatants of HBIG-PBCA-NP group and HBIG group cultured with media without HBIG-PBCA-NP and HBIG kept decreasing at day 5 and 7,then rebounded at day 9 and 11.HBsAg titera in supernatants of 0.1,1.0,5.0 IU/mL HBIG-PBCA-NP group were all significantly different from those in HBIG group at day 9[(31.31±1.98)μg/L vs(40.62±2.99)μg/L,(23.79±1.31)μg/L vs(36.51±2.12)μg/L,(19.91±1.74)μg/L vs(33.03±1.65)μg/L;F=412.24,P＜0.01].Couclusion HBIG-PBCA-NP can inhibit secretions of HgsAg and HBV DNA in vitro,which is more effective than HBIG.     

乙型肝炎免疫球蛋白聚氰基丙烯酸正丁酯纳米粒抑制HBsAg、HBV DNA分泌的体外实验

Objective To investigate the inhibitive activities of hepatitis B immunoglobulin(HBIG)poly(butylcynaoacrylate)nanoparticles(HBIG-PBCA-NP)to hepatitis B surface antigen(HBsAg)and hepatitis B virus(HBV)DNA secretions using HBV infected cell model in vitro.Methods HepG 2.2.15 cells were cultured with media containing HBIG-PBCA-NP or HBIG for several days,or cultured with HBIG-PBC-NP and HBIG for 2 days and without HBIG-PBCA-NP and HBIG from day 3.The supernatants at different time points were collected for quantitative detection of HBsAg and HBV DNA.The comparisons between groups were done by variance analysis.Resalts Secretions of HBsAg and HBV DNA in supernatants of HepG2.2.15 cultured with 0.1-10.0 IU/mL of HBIG-PBCA-NP and HBIG were inhibited significantly compared with control group.HBsAg titers and HBV DNA levels in supernatants of HBIG-PBCA-NP group and HBIG group cultured with media without HBIG-PBCA-NP and HBIG kept decreasing at day 5 and 7,then rebounded at day 9 and 11.HBsAg titera in supernatants of 0.1,1.0,5.0 IU/mL HBIG-PBCA-NP group were all significantly different from those in HBIG group at day 9[(31.31±1.98)μg/L vs(40.62±2.99)μg/L,(23.79±1.31)μg/L vs(36.51±2.12)μg/L,(19.91±1.74)μg/L vs(33.03±1.65)μg/L;F=412.24,P＜0.01].Couclusion HBIG-PBCA-NP can inhibit secretions of HgsAg and HBV DNA in vitro,which is more effective than HBIG.