Antibodies to synthetic peptides from the preS1 region of the hepatitis B virus (HBV) envelope (env) protein are virus-neutralizing and protective

Hepatitis B virus (HBV) envelope (env) proteins contain three antigenic domains designated S, preS2 and preS1. Studies with synthetic peptide immunogens demonstrated the role of preS2 epitopes in protection against HBV infection. The preS1 domain is implicated in virus-cell receptor interactions suggesting that anti-preS1-specific antibodies should neutralize the infectivity of HBV by blocking virus attachment to cells. We present here evidence that an antiserum to a peptide from the preS1 sequence, anti-preS(21-47), is virus-neutralizing and that active immunization of chimpanzees with a longer peptide derived from the preS1 sequence, preS(12-47), elicits antibodies protective against HBV infection. These results establish the role of the preS1 domain in the process of virus neutralization and the potential of synthetic preS1 analogues for hepatitis B vaccination.     

Oral immunogenicity of potato-derived HBsAg middle protein in BALB/c mice

The antibodies to preS2 synthetic peptides have been probed to neutralize hepatitis B virus (HBV), and also the addition of preS2 sequence could enhance the antibody response compared with a conventional vaccine in the non- and low responders. Previously, we generated transgenic potatoes expressing middle protein, which contains additional 55 amino acid preS2 region at the N-terminus of the S protein, of HBV to determine the feasibility of developing a plant-delivered HBV vaccine. In this study, we monitored the immune response after induction of immunoglobulin by boosting and assessed the efficacy of the mucosal immune response with regard to generate IgA antibodies. The HBsAg middle protein expressed in our transgenic potatoes was well immunized at low antigenic quantities in mice and the induced anti-S or anti-preS2 antibodies were sustained for the whole period without decrease. Orally delivery of plant-derived HBsAg middle protein to mice resulted in fecal anti-S or anti-preS2 as well as serum IgG. In addition, we used antibodies induced from the immunized mice with the potato-derived rHBsAg in competition assay as competitors to confirm the binding ability of preS2 antibodies to surface antigen of hepatitis virus. Anti-preS2 antibodies induced from immunized mice with transgenic potatoes effectively competed with anti-preS2 murine antibody H8 as expected. From these results, the inclusion of preS2 antigen to HBV plant vaccine may provide additional protective immunity in the HBV prevention.     

乙肝病毒前S基因变异与乙肝肝硬化的相关性研究

目的 探讨乙型肝炎病毒(hepatitis B virus,HBV)前S基因(preS)变异与HBV感染后肝硬化发生的相关性。方法 采用病例对照研究设计,对50例慢性乙型肝炎(chronic hepatitis B,CHB)患者和67例乙肝肝硬化(liver cirrhosis,LC)患者的血清HBVPreS基因进行扩增和测序,应用MEGA7软件进行序列比对,使用SPSS 16.0统计软件对PreS基因热点变异与LC的相关性进行单因素和多因素分析。结果 单因素分析结果表明,HBV基因组PreS区T3116m(χ²=8.470,P=0.004)、A49m(χ²=4.939,P=0.026)、T53m(χ²=6.683,P=0.010)、A109m(χ²=5.868,P=0.015)及PreS缺失变异(χ²=12.154,P=0.000)与LC发生显著相关。PreS缺失变异在失代偿期LC患者中的频率(63.16%)显著高于代偿期LC患者(31.03%)(P=0.007)。多因素分析结果表明,年龄越大(OR=1.07,95%CI:1.02~1.11)、T3116m(OR=4.18,95%CI:1.39~12.61)、PreS缺失变异(OR=7.20,95%CI:2.09~24.80)是LC的独立危险因素。结论 HBV PreS缺失变异与T3116m是乙型肝炎患者进展至LC的危险变异,还需要大样本人群进行验证。     

High immunogenicity of a hydrophilic component of the hepatitis B virus preS1 sequence exposed on the surface of three virus-like particle carriers

The preS1phil, a hydrophilic component of the hepatitis B virus (HBV) preS1 sequence, was exposed on the surface of three widely used virus-like particle (VLP) carriers by (i) insertion into the HI loop of the murine polyomavirus (MPyV) VP1, (ii) N-terminal addition to the hepatitis B surface (HBs) protein, and (iii) insertion into the major immunodominant region (MIR) of three hepatitis B core (HBc) vectors with different structure of their C-termini. Adjuvant-free immunisation of Balb/c mice demonstrated high preS1-specific antibody responses, but strong Th1 cell activation with efficient induction of IgG2a isotype antibodies was observed only in those VLPs, and namely in two of three HBc derivatives, which contained packaged RNA.     

DNA-mediated immunization to hepatitis B virus envelope proteins: preS antigen secretion enhances the humoral response

In order to design optimized DNA vectors as genetic vaccines against infections with the hepatitis B virus (HBV) we investigated if secretion or retention of the viral antigens has an influence on the quality and quantity of the humoral immune response. Intramuscular injection of plasmid DNA encoding the HBV large L envelope protein, known to be retained within host cells, induced only a weak response in mice whereas a vector expressing the secretion-competent small S envelope protein elicited strong and sustained immunity. Immunization with rearranged envelope genes further demonstrated that secretion affects the magnitude of the immune response. In situ expression of modified small and middle envelope genes carrying C-terminally attached epitopes are derived from the preS1 region of L generated high titers of preS1- and preS2-specific antibodies, unless antigen secretion was blocked. Accessibility of preS antigens to B-cells that can be achieved by generating extracellular forms of the envelope proteins is thus critical to elicit humoral responses. Such DNA constructs carrying preS1 determinants are promising candidates for the development of multivalent HBV vaccines.     

Immunogenicity of a hepatitis B DNA vaccine administered to chronic HBV carriers

Hepatitis B virus (HBV) is the major pathogen of chronic hepatitis and liver disease worldwide. Despite the availability of effective vaccines against hepatitis B for many years, over 370 million people remain persistently infected with HBV. Viral persistence is thought to be related to poor HBV-specific T-cell responses. Based on clinical data, the development of efficient methods capable of inducing strong T-cell responses is an important and primary step toward the development of immunotherapeutics against chronic HBV infection. We designed a phase I clinical trial in chronic HBV carriers to assess safety, tolerability and immunogenicity of a DNA vaccine expressing HBV small (S) and middle (preS2 +S) envelope proteins. After occurrence of lamivudine breakthrough, 10 HBeAg positive patients with chronic hepatitis B were followed longitudinally before, during and after DNA vaccine therapy. Immunizations were well tolerated and adverse physical events were mild and considered unrelated to the vaccine. Proliferative responses to hepatitis B surface antigen (HBsAg) were detected in two patients after DNA injections. Following three injections of vaccine, interferon (IFN)-gamma-producing T-cells specific for the preS2 or the S antigen were detectable in 50 and 100% of the patients, respectively. Each patient recognized at least one peptide within the envelope domain encoded by the vaccine. Anti-preS2 antibodies and seroconversion to anti-HBe were detected in two patients. This study shows evidences for the safety and immunological efficacy of HBV-DNA vaccination and demonstrates that DNA vaccination can restore or activate T-cell responses in chronic HBV carriers.     

实时荧光PCR法检测乙型肝炎病毒基因型

目的:建立实时荧光PCR法检测乙型肝炎病毒(HBV)基因型。方法:根据乙肝病毒基因序列选取保守区域设计引物,结合不同基因型的差异设计各型的特异荧光探针检测乙型肝炎基因B、C型。结果:200例HBV感染者中基因B型70例占35%,基因C型120例占60%,基因B,C混合型10例占5%,未捡出基因型A、D、E、F,分别取B、C型基因标本10例进行测序结果一致。结论:实时荧光PCR检测乙型肝炎基因型操作简单、快速、适合临床常规检测。     

Phylogenetic analysis of isolates from new cases of HBV infection in Southern Italy

The level of endemicity of hepatitis B virus (HBV) infections in Italy is low and genotype D infections predominant. New HBV strains may however be introduced as a result of movements of people from regions of high endemicity. The aim of the present study was to determine whether strains from new cases of acute hepatitis B detected in southern Italy were due to endemic or new HBV strains. We studied 34 isolates from patients with acute hepatitis B infection, and 35 from chronic hepatitis B patients. A phylogenetic analysis of preS/S region was done by comparing the sequences from the acute and chronic cases with references sequences. The study showed that 44% of strain from acute hepatitis B patients were of genotype A, 53% of genotype D, and 3% of genotype E. The molecular analysis of isolates from acute hepatitis B patients from Sicily showed a change in the local epidemiology of this infection, with an increase in HBV/A infections and a clustering effect for HBV D2, possibly correlated to immigration. The introduction of new genotypes , could have an effect on HBV-correlated diseases due to the different association between genotype, liver disease and response to antiviral therapy.     

乙型肝炎病毒B基因亚型(Ba,Bj)半巢式PCR检测方法的建立

目的 建立一种灵敏特异且简便易行的乙型肝炎病毒(HBV)B基因Ba和Bj亚型分型方法.方法 用DNAStar软件比较分析GenBank中登录的B基因型HBV(HBV/B)和C基因型HBV(HBV/C)的基因序列,分别设计出HBV/B型特异性引物HB及Ba和Bj基因亚型特异性引物BA和BJ.第一轮PCR反应以HBV/B型特异性引物HB作为上游引物,以日本学者Sugauchi等设计的引物HBAS-4V作为下游引物(外引物);第二轮PCR反应同样以HB作为上游引物,亚型特异性引物BA和BJ作为下游引物(内引物),在同一个反应管中进行.根据PCR产物片段的大小判定B基因亚型.随机选取实验室内经型特异性引物PCR法鉴定为HBV/B(56份)及经preS/S区序列测定证实为HBV/C(15份)的HBV慢性感染者血清标本共71份,以研究设计的引物进行半巢式PCR反应,检测Ba和Bj基因亚型,并以载有HBV Bj亚型基因组的质粒作为Bj亚型的阳性对照.然后随机选取15份B型样本的第一轮PCR产物直接测序,利用Blast和DNAStar软件将测序结果与GenBank中登录的Ba及Bj亚型序列进行同源性分析,验证该半巢式PCR法的准确性.结果 56份HBV/B血清标本经该半巢式PCR法检测,均为Ba亚型,随机选取的15份B型PCR产物直接测序,结果均为Ba亚型,与研究中应用的半巢式PCR方法检测结果一致.15份HBV/C的血清标本检测结果均为阴性.结论 建立了HBV Ba和Bj亚型半巢式PCR法.该方法灵敏、特异、简便、易行,可用于临床和流行病学大样本检测.     

Hepatitis B virus (HBV)-derived DRB1*0101-restricted CD4 T-cell epitopes help in the development of HBV-specific CD8+ T cells in vivo

We previously identified two HLA-DRB1*0101-restricted epitopes in hepatitis B virus (HBV) X protein (HBx) and in HBV envelope proteins (preS2). To evaluated their help in the development of CD8+ T-cell responses, mice transgenic for human class I and class II HLA molecules were immunized with HBV-T helper constructs. The preS2 epitope favored a well-balanced response with CD4+ and CD8+ T cells producing IFN-γ, IL-2 and TNF-α. The response was focused on CD8+ T cells with the HBx epitope. Fine characterization of helper activities may meet clinical needs in terms of enhancing the potency of preventive or therapeutic polyepitope vaccines.     

Recombinant hepatitis B core antigen carrying preS1 epitopes induce immune response against chronic HBV infection

Many studies have provided evidence that core antigen of hepatitis B virus (HBcAg) is extremely immunogenic, HBcAg can be function as both a T-cell-dependent antigen and a T-cell-independent antigen, and thus may be a promising candidate for therapeutic vaccine for control of chronic HBV infection. HBcAg is also an effective carrier for heterologous peptide epitopes. The preS1 is a surface protein of HBV and is immunogenic at the T and B cell level. The amino acid sequence 21-47 of preS1 is crucial for HBV binding to human hepatocytes as well as to PBMC and haematopoietic cell lines of the B cell lineage. Here we expressed a chimeric protein named HBVCS1, created by fusing the preS1 sequence 3-55 to the carboxyl terminus of the truncated HBcAg sequence 1-155 in E. coli. Analysis of its antigenicity and immunogenicity revealed that both HBc and preS1 epitopes are surface accessible, and that fusion of preS1 did not affect the HBc antigenicity and immunogenicity of the truncated HBc sequence. HBVCS1 induced strong anti-HBc and moderate anti-preS1 immune responses as well specific T-cell response in Balb/c mice. HBVCS1 vaccination reduced of the titer of HBsAg and HBV DNA in sera of HBV-Tg mice. These results indicate that HBVCS1 may have potential as a therapeutic vaccine for treatment of HBV chronic infection.     

Impact of HBV genotypes A and D genetic variability on infection evolution

HBV is characterized by a high genetic variability, which is the basis of its classification into eight genotypes (A–H). HBV infection is associated with different outcomes, from self-limiting acute hepatitis to active chronic hepatitis, asymptomatic carriage, and occult infection.The aim of this study was to analyze the genetic variability of HBV genotypes A and D isolates from 79 cases of self-limiting acute hepatitis and chronic hepatitis, in order to identify HBV variants associated with resolution or chronicity of acute HBV infection. The entire preS–S sequence and a fragment of 346 bp of the preC–C region, containing Enhancer II and Basal Core Promoter sequences, were analyzed. A phylogenetic analysis of preS/S region showed that the 45.45% (15/33) of isolates from acute hepatitis cases were genotype A compared to 8.69% (4/46) of chronic hepatitis cases. (p = 0.0002). Mutations associated with immune-escape (T131N, D144A/E, G145K), amino acid polymorphisms in “a determinant” domain of S protein and mutations/deletions in preC/C region were found in isolates from acute and chronic hepatitis B cases. In this study mutations/deletions in preS–S and preC–C regions, usually associated with fulminant acute hepatitis, advanced forms of liver disease and increased risk for HCC, were identified in HBV strains of genotype A and D obtained both from patients with self-limiting acute HBV infection and from persistent infected patients. This founding probably is due to the natural viral evolution under host immune response and to the circulation of a wide variety of HBV strains in our geographic area because of the ancient introduction of genotype D and the migrant fluxes from North Africa. Moreover, the analysis of circulation of new HBV antigenic variants is fundamental for the epidemiological surveys and for the evaluation of the impact of viral evolution on vaccine prophylaxis strategies.     

Physicochemical and immunological characterization of hepatitis B virus envelope particles exclusively consisting of the entire L (pre-S1 + pre-S2 + S) protein

The hepatitis B virus (HBV) envelope (env) protein is composed of three regions; the 108- or 119-residue pre-S1 region involved in the direct interaction with hepatocytes, the 55-residue pre-S2 region associated with the polymerized albumin-mediated interaction, and the major 226-residue S protein region. Thus, to improve the immunogenic potency of conventional HB vaccines, development of a new vaccine containing the entire pre-S1 region in addition to pre-S2 and S is desired. We previously reported the efficient production of the HBV env L (pre-S1 + pre-S2 + S) protein in the recombinant yeast cells [J Biol Chem 267 (1992) 1953]. In this study, the HBV env L protein produced as nano-particles in yeast has been purified and characterized. By equilibrium sedimentation, an average molecular weight of L particle was estimated to be approximately 6.4 x 10(6), indicating that about 110 molecules of L proteins are assembled into an L particle. By atomic force microscopy in a moist atmosphere, the L particles were observed as large spherical particles with a diameter of 50-500 nm. The L particles were stable on short-time heating at a high temperature and long-time storage at a low temperature but rather unstable on repeated freezing and thawing and treatment with dithiothreitol. When immunized in mice, L particles elicited efficiently and simultaneously the anti-S, anti-pre-S2, and anti-pre-S1 antibodies. The ED(50) values in mice for the anti-S and anti-pre-S2 antibodies were similar to those elicited by the M (pre-S2 + S) particles. Furthermore, the anti-pre-S1 rabbit antibodies were found to recognize various segments of the pre-S1 region, including the pre-S1 (21-47) segment. These results show the high ability of L particles to induce all antibodies against HBV env proteins, hence promising the future application of L particles for the next generation HB vaccine.     

HBV—DNA定量与HBV血清学标志物的相关性探讨

目的探讨HBV—DNA定量与HBV血清学标志物（HBV—M）的相关性。方法采用实时荧光定量PCR（FQ—PCR）检测449例乙肝感染者血清的HBV—DNA含量,并用酶联免疫吸附试验（ELISA）对其血清学标志物进行检测。结果在不同HBV—M模式中,HBV—DNA与preS1总检出率无显著差异。在模式HBsAg（＋）、HBeAg（＋）和HBcAb（＋）中血清HB—DNA含量明显高于其他模式。在278例HBV—DNA阳性的标本中,HBV—DNA与preS1检出率无显著差异（P〉0．05）,HBV—DNA与HBeAg检出率有显著差异（P〈0．01）,同时preS1阳性组HBV～DNA定量值显著高于preS1阴性组。结论HBV—DNA或preS1与HBV复制密切相关,preS1较HBeAg更能敏感反映HBV在体内的复制状况,联合检测HBV—DNA与HBV血清学标志物,在乙型肝炎的诊断治疗中更有重要的临床指导价值。     

血清HBV前S1抗原在乙型肝炎诊断及判断预后中的作用

目的了解乙型肝炎前S1抗原(HBVpreS1-Ag)与乙型肝炎病毒(HBV)复制的关系,及诊断乙型肝炎的价值。方法采用酶联免疫吸附试验(ELISA)的方法对276例携带乙型肝炎不同病毒标志物的慢性乙型肝炎患者进行HBVpreS1-Ag,HBV-M测定并与HBVDNA做对比分析,同时测定患者的生化指标丙氨酸氨基转移酶(ALT),门冬氨酸氨基转移酶(AST),分析前S1抗原与AST、ALT之间的关系。结果HBV大三阳组与前S1抗原和HBVDNA符合率分别为70.8%,77.1%,P>0.05,患者血清HBVpreS1-Ag、HBeAg和HBVDNA检出率高度符合。HBV小三阳组与前S1抗原和HBVDNA符合率分别为29.5%和26.2%,说明部分HBeAg阴性患者仍有病毒复制。276例患者中preS1-Ag阳性组与preS1-Ag阴性组比较,ALT、AST升高率均有显著性差异。结论前S1抗原能够敏感的反映乙型肝炎的复制情况,尤其可以反映HBeAg阴性的乙型肝炎患者是否有病毒复制。     

Impact of pooling on accuracy of hepatitis B virus surface antigen screening of blood donations

Expenditure on screening blood donations in developing countries can be reduced by testing donations in pools. This study evaluated serological screening in pools for hepatitis B virus (HBV) at the Israeli national blood bank and a hospital blood bank in Gaza, the Palestinian Authority. The accuracy of HBV surface antigen (HBsAg) enzyme immunoassay performed on pools of 3-24 samples was compared with individual tests. Delay in detecting positive samples due to dilution in pools and the possibility of antibody-antigen neutralization were analyzed. The sensitivity of pooled testing for HBsAg was 93-99%, prolonging the window period by 5 days (8.3%). Neutralization of HBsAg by hepatitis B surface antibodies (anti-HBs) could be minimized by testing immediately after pooling. Serological testing for HBsAg in pools may be performed using manually created pools of up to six samples, with 5% loss in sensitivity and a risk of neutralization by anti-HBs present in the donor population. Pooling can therefore be considered as an option only in countries with a low prevalence of HBV.     

乙肝病毒preS1基因与截短C基因真核表达载体构建及表达

目的建立乙型肝炎病毒（HCV）preS1基因与截短C基因真核表达载体，并在CHO细胞中瞬时表达。方法PCR方法扩增HBV核心区羧基端部分缺失的基因片段和preS1全基因，克隆入真核表达载体pcDNA3．1（-）后测序鉴定，并通过脂质体瞬时转染CHO细胞。结果构建了真核表达载体pcDNA3．1（-）-Ct-preS1，成功转染CHO细胞，间接免疫荧光和RT—PCR证实pcDNA3．1（-）-Ct-preS1在CHO中表达截短的核心基因和preS1基因融合蛋白。结论成功构建preS1基因与截短C基因真核表达载体，可在CHO细胞中瞬时表达，为深入研究HBV基因免疫奠定了基础。     

Audit of bloodborne virus infections in injecting drug users in general practice

Two hundred and ninety patients attending a single general practice in Edinburgh were known to have used illegal drugs, 145 of whom were identified as past or present injectors. Data on bloodborne virus infections and immunisation against hepatitis B virus (HBV) were gathered during 1998, attempts were made to improve the level of testing for bloodborne viruses and immunisation against HBV, and follow up was carried out between October 1999 and February 2000. One hundred and fifteen patients were studied in detail. Evidence of previous HBV infection was found in 31 of 71 tested in 1998 (44%) and 40 of 99 tested at follow up (40%). In 1998 54 out of the 75 tested for hepatitis C antibodies (72%) were positive compared with 73 out of 108 (68%) at follow up. Twenty-six of the 80 tested for HIV antibodies were positive in 1998 (33%) and 26 of 105 at follow up (25%). Large numbers of injecting drug users in our study were found to be not immune to hepatitis B and required immunisation. An abbreviated protocol for immunisation was devised, including post vaccination checks and boosting as necessary. Hepatitis C testing was requested after counselling in most cases, resulting in important and positive interventions. Prevention opportunities for all three bloodborne viruses were identified.     

乙型肝炎感染者抗心磷脂抗体的研究

为了解抗心磷脂抗体（ＡＣＡ）在乙型肝炎病毒（ＨＢＶ）感染中的流行情况,采用ＥＬＩＳＡ法对１６２例ＨＢＶ感得和１０２例正常对照者作ＡＣＡ测定。结果表明,ＨＢＶ感染者ＡＣＡ阳性率（１５．４３％）与正常对照组（３．９２％）相比有显著性升高;在ＨＢＶ感染乾中,肝功能异常者ＡＣＡ阳性率同于肝功能正常者,说明ＡＣＡ可常见乙型肝炎感染者,并可能与乙型肝炎的病情有关。     

长春地区乙型肝炎病毒基因分型与肝病发病关系的研究

目的了解长春地区乙型肝炎(乙肝)患者基因型特点及与肝炎严重程度、疾病转归的关系,以指导临床对疾病进展的判断和指导临床用药。方法选择216例乙肝病毒(HBV)阳性肝炎患者,年龄33-87岁,平均(60．5±11．4)岁。病变程度的判断根据2000年《病毒性肝炎防治方案》中的诊断标准。应用巢式聚合酶链反应方法(nPCR)扩增HBV S基因组序列,用第二轮PCR产物直接进行限制性片段长度多态性(RFLP)分析;然后用HBV S基因扩增产物采用Sanger双脱氧链终止法进行DNA测序,将所得到的核苷酸序列及推测的相应氨基酸序列通过DNASIS软件处理,并与GenBank中已发表的HBV中国株及国外株进行同源性比较以确定HBV的基因型,证明用S基因序列的RFLP法HBV分型结果与用全基因组序列的基因分析是一致的。表明S基因序列RFLP法的基因分型结果与S基因测序分型结果是一致的。结果216例HBV DNA阳性标本中单基因型分别检测出A、B、C、D四种,其中单基因型中A型有1例(0．46％),B型有19例(8．8％),C型有175例(81．02％),D型有21例(9．72％)。86例HBV DNA阳性住院患者标本中,C型为感染的主要基因型,69例(80．23％)。B型次之,9例(10．47％)。6例原发性肝癌均为C型;20例肝炎后肝硬化的患者中有17例(85．0％)为C型。结论长春地区HBV基因型仍以C型为主(81．02％),B、D型次之(分别是8．8％和9．72％)。同时结果显示长春地区HBV感染有基因多样性趋势,表现在检测出了A单基因型。肝癌、肝硬化与C基因型HBV的相关性最大。C基因型HBV DNA拷贝数较非C基因型高,提示与HBV DNA在C型患者体内长期存在有关。HBV病毒载量与肝脏病变严重程度的关系无统计学意义。