丙型肝炎病毒多表位抗原重组体免疫原性分析

目的：研究丙型肝炎病毒(HCV)多表位抗原重组体在大肠杆菌中的非融合表达及其免疫原性分析。方法：利用DNA重组技术将构建的HCV多表位抗原重组体克隆入原核表达载体pBV220并在BL-21中表达，非融合表达蛋白经SDS-PAGE检测，排阻层析纯化，利用ELISA和免疫印迹分析其抗原反应性。免疫昆明鼠和猕猴，并检测其抗体和特异性CTL(Cyto-toxic T lymphocyte)，在抗体转阴后再次用HCV病人血清攻击以检测其免疫应答能力。结果：HCV多表位重组体在pBV220／BL-21中表达量占菌体总蛋白量的15％。Western-blot和ELISA分析表明HCV多表位抗原能与HCV病人血清特异性结合，抗体水平和特异性CTL检测结果显示该抗原肽能诱导小鼠和猕猴产生较好的抗体水平和特异性CTL效应。用病人血清再次攻击后受试动物的抗体迅速阳转。结论：表达的多表位重组体具有特异的抗原反应性和免疫原性。     

双歧杆菌完整肽聚糖对重组乙肝表面抗原的佐剂效应

目的 探讨双歧杆菌完整肽聚糖对重组乙肝表面抗原的吸附作用及其佐剂效应。方法 从双歧杆菌细胞壁提取完整肽聚糖，以不同方式与重组乙肝表面抗原结合，检测其对重组乙肝表面抗原的吸附作用；制备免疫原接种BALB／c小鼠，观察小鼠免疫后状态和生长情况，检测小鼠血清特异性抗体应答情况的变化。结果 在磷酸盐缓冲液中，完整肽聚糖对重组乙肝表面抗原的吸附呈剂量依赖性，作为佐剂免疫小鼠后无毒副反应出现，小鼠血清抗体阳性率和抗体滴度明显提高，IgC2a/IgG1增大。结论 双歧杆菌完整肽聚糖能够吸附重组乙肝表面抗原，增强机体相应的体液免疫应答和细胞免疫应答，具备良好的免疫佐剂效应。     

282例HBV感染无症状表面抗原阳性者血清ALT与乙肝前S1抗原的检测

目的了解乙型肝炎病毒（HBV）感染无症状表面抗原阳性者血清ALT和乙肝前S1抗原的状况。方法用ELISA法检测血清标志物（HBsAg、抗HBs、HBeAg、抗HBe、抗HBc）和乙肝前S1抗原,用日立7060全自动生化分析仪检测血清ALT。结果 282例无症状表面抗原阳性者,乙肝前S1抗原总检出率为37.6%;ALT升高87例,占总人数的30.8%;ALT升高的87例患者中前S1抗原检出率为67.8%;ALT正常的195例患者中前S1抗原检出率为24.1%,两组比较差异有统计学意义（P〈0.01）。在282例无症状表面抗原阳性者中,HBeAg阳性组,乙肝前S1抗原检出率为73.9%,ALT异常阳性率为52.2%;HBeAg阴性组,乙肝前S1抗原检出率为31.0%,ALT异常阳性率为25.6%,两组比较差异有统计学意义（P〈0.01）。结论乙肝病毒携带者不能完全排除ALT正常情况下的病毒复制;血清中出现HBeAb并不一定表示HBV复制停止。因此,对于无症状表面抗原阳性者应进行定期复查,监测其乙肝血清标志物、ALT和前S1抗原。     

人类肝素酶B细胞表位的预测和免疫原性鉴定

目的 预测并鉴定肝素酶(heparanase)蛋白B细胞表位免疫原性.方法 以肝素酶蛋白的氨基酸序列为基础,采用DNAStar分析软件以及Bcepred在线二级结构分析工具分析其蛋白二级结构并预测B细胞表位.根据预测结果 ,采用8分支多抗原肽结构合成针对该表位的抗原肽,将后者与通用型T辅助表位人IL-1β线性短肽(VQGEESNDK,氨基酸163～171)联合免疫日本白毛黑眼兔,检测免疫血清效价,鉴定其特异性和免疫原性.结果 软件预测显示,肝素酶蛋白大亚基的第1～15位(MAP1)、第279～293位(MAP2)及175～189位(MAP3)氨基酸序列最可能为其优势B细胞表位.间接酶联免疫吸附试验、免疫印迹及免疫组化分析,证实MAP1、MAP2及MAP3均能诱导机体产生高滴度抗体,但仅MAP1、MAP2抗体具有高特异性,MAP2抗体与肝癌组织的结合力最强.结论 肝素酶大亚基的第1～15位、第279～293位氨基酸为其优势B细胞表位,其中第279～293位氨基酸的免疫原性最强,这为肝素酶多肽抗体及B细胞优势短肽疫苗研制提供了理论依据.     

脂质体佐剂对增强HBsAg免疫原性的作用

利用DC Chol制备粒径为 5 0～ 30 0nm的正电荷脂质体 ,作为乙肝疫苗 (HBsAg)的佐剂 ,免疫BALB/c小鼠后进行血清中特异性抗体IgG1及IgG2a、脾细胞产生细胞因子的检测。结果该脂质体佐剂所诱导的抗体亚类以IgG2a为主 ,脾细胞产生的IL 2、IL 5、IFN γ分别比铝佐剂组高 16 5倍、 10倍、 2倍。表明该脂质体佐剂可以诱导很强的细胞免疫反应 ,是一种能促进Th1和Th2均衡应答的佐剂 ,值得作进一步的研究     

单克隆抗体组对重组乙肝表面抗原突变体的结合能力分析

世界卫生组织(WHO)报道,超过20亿的人曾经感染过HBV[1],其中有3.5亿是慢性持续感染[2],以及每年超过百万的慢性乙肝携带者死于肝硬化或肝癌[3].HBV是一种双链环状DNA病毒[4],DNA长度约为3 200 bp,是通过一RNA作为媒介进行复制的[5],主要是因为DNA聚合酶具有的逆转录酶活性.正是由于逆转录复制的错误率较高,导致了乙肝病毒基因易发生变异,倘若发生在编码表面抗原的抗体结合部位(aa124～147)的基因发生变异,将导致部分突变的抗原对野生型抗原有高亲和力的单克隆抗体(mAb)的结合力降低,从而引起乙肝表面抗原诊断试剂盒的漏检.故筛选对不同突变位点的乙肝表面抗原突变体具有高亲和力的mAb至关重要,本实验对乙肝表面抗原mAb库中的59多个mAb进行分析,并对不同类型的mAb归类,找出互补的mAb进行组合来制备和完善乙肝表面抗原诊断试剂盒.     

胰腺癌高表达抗原MUC4 CTL表位肽的体内免疫原性

目的:检测来源于黏蛋白4(MUC4)的人白细胞抗原(HLA)-A2限制性表位肽免疫BALB/c小鼠后产生细胞免疫应答的水平,筛选出体内具有免疫原性的HLA-A2限制性表位肽。方法:将来源于MUC4的候选HLA-A2限制性表位肽、通用性Th表位和弗氏不完全佐剂联合应用皮下免疫BALB/c小鼠,用酶联免疫斑点实验(ELISPOT)和酶联免疫吸附实验(ELISA)检测小鼠脾细胞表位肽特异性细胞免疫应答的水平,体内细胞毒实验活性检测候选肽诱导细胞毒性T淋巴细胞(cytotoxic lymphocyte,CTL)的能力,并用流式细胞术检测表位肽特异性的CD8+T细胞所占比例。结果:在检测的4个表位肽中,P2004-1Y9V诱导BALB/c小鼠产生的细胞免疫应答最强,细胞毒实验结果显示,P2004和P2004-1Y9V对CAPAN-2细胞均有一定的杀伤作用,且P2004-1Y9V特异性CTLs对CAPAN-2细胞杀伤率高于原肽(P0.05)。胞内因子染色实验进一步表明P2004-1Y9V免疫后可产生特异性的CD8~+T细胞。结论:在来源于MUC4的HLA-A2限制性表位肽中,P2004-1Y9V具有较强的体内免疫原性,可以作为潜在的肿瘤多肽疫苗应用于临床研究。     

HPV16 E5多表位肽免疫原性研究

目的 筛选人乳头瘤病毒16型（HPV16）E5蛋白多表位肽段,并评估其诱导小鼠产生特异性体液免疫和细胞免疫的免疫原性反应。方法 通过Uniprot获得HPV16 E5蛋白的氨基酸序列,采用EXPASY和SYFPEITHI等软件预测HPV16 E5蛋白的表位,筛选出富含B细胞和CTL表位的氨基酸肽段——HPV16 E5蛋白N端处aa28-46(LIRPLLLSVSTYTSLIILV),进一步用该多表位肽免疫C57BL/6小鼠,评估其诱导产生特异性体液免疫和细胞免疫的反应。结果 该肽段可诱导小鼠产生较高水平的特异性IgG抗体,且抗体滴度随着免疫次数增加而升高,同时可诱导小鼠产生特异性的CTL反应,在效靶比为40∶1时,对靶细胞产生显著的特异性杀伤作用。结论 HPV16 E5蛋白多表位肽aa28-46(LIRPLLLSVSTYTSLIILV)具有良好的免疫原性,可为基于HPV16 E5蛋白的疫苗研究提供基础。     

钩端螺旋体抗原表位预测、重组、表达及免疫原性分析

目的应用生物信息学方法预测两种钩端螺旋体外膜蛋白的表位，结合基因工程手段进行表位重组、表达和免疫原性分析。方法用预测程序ProPred和ANTIGENIC预测LipL32和OmpL1的表位，应用PCR技术合成重组表位基因片段，克隆PCR产物构建重组质粒，测序验证。在BL21（DE3）中诱导表达融合蛋白。纯化该融合蛋白，免疫BALB／c小鼠，显微镜凝集试验（MAT法）测定抗体效价。结果在LipL32和OmpL1中各预测到2个既具有MHC结合肽特性又具有B细胞表位特征的肽段。PCR合成的重组表位基因序列中没有出现移码和碱基置换。纯化后融合蛋白纯度〉90％。融合蛋白产生的抗体效价为75．79，融合头（运载蛋白）抗体效价为10．62。结论重组表位具有一定免疫原性。为相关蛋白的表位重组和亚单位疫苗等方面的研究打下了良好的基础。     

Different immunogenicity of H-2 Kb-restricted epitopes in natural variants of the hepatitis B surface antigen

The small hepatitis B surface antigen (HBsAg) of hepatitis B virus (HBV) has limited variability, but some serotypes and genotypes have been defined. Although no biological or pathogenetic differences could be traced to HBV serotypes, the clinical picture, response to treatment and long-term prognosis of HBV infection may vary with the HBV genotype, possibly due to differences in specific T cell recognition of HBV antigens from different genotypes. We analyzed murine CD8(+) T cell responses to two K(b)-restricted HBsAg epitopes primed by four different HBsAg variants using protein- and DNA-based vaccination protocols. The K(b)-binding S(208-215) epitope 1 is processed from exogenous but not endogenous HBsAg. Variants of epitope 1 differing at two positions within the epitope (ILSPFLPL in ayw/adr versus IVSPFIPL in adw2) efficiently primed cross-reactive CD8(+) T cell responses. In contrast, the exchange of an N-terminal flanking residue (S to N) completely eliminated the immunogenicity of epitope 1. The K(b)-binding S(190-197) epitope 2 is processed from endogenous but not exogenous HBsAg. A single-residue exchange within the epitope (VWLSVIWM in ayw/adr versus VWLSAIWM in adw2) completely eliminated the immunogenicity of epitope 2. Single, conservative residue exchanges can thus give rise to diverging CD8(+) T cell repertoires, suggesting an impressive complexity and flexibility of the CD8(+) T cell repertoire to antigen variants from viruses with limited diversity.     

Immunogenicity of recombinant core particles of hepatitis B virus containing epitopes of human immunodeficiency virus 1 core antigen

Summary A Gag protein segment of human immunodeficiency virus 1 (HIV-1) has been fused to a C terminally truncated core antigen of hepatitis B virus (HBcAg) using anE. coli expression system. Fusion of 90 amino acids of HIV-1 Gag protein to HBcAg still allowed the formation of capsids presenting on their surface epitopes of HIV-1 core protein, whereas fusion of 317, 189, or 100 amino acids of Gag prevented self-assembly of chimeric particles. Mice immunized with recombinant particles emulsified with Freund's complete adjuvant (CFA) or aluminium hydroxide developed high anti-HBcAg titers. However, anti-HIVp24 antibodies were detected only in mice inoculated with immunogen emulsified with CFA.     

Mutated epitopes of hepatitis B surface antigen fused to the core antigen of the virus induce antibodies that react with the native surface antigen

Fusion of peptide epitopes to the core antigen (HBcAg) of hepatitis B virus (HBV) enhances their immunogenicity, both quantitatively and qualitatively. In a number of vaccine-induced mutants of HBV, glycine₁₄₅ of the surface antigen S polypeptide (HBsAg) has been replaced by arginine, resulting in loss of cross-reactivity with antibodies to normal (wild-type) HBsAg. HBcAg fusion proteins carrying the immunodominant epitope of HBsAg, in which glycine₁₄₅ was replaced by arginine, glutamic acid, or lysine, were produced in Escherichia coli and formed particles that displayed HBc antigenicity and immunogenicity similar to that of HBcAg itself. The fusion proteins also elicited T-cell-proliferative responsiveness to HBcAg and HBsAg. Fusions carrying either wild-type or mutated epitopes of HBsAg showed HBs antigenicity in immunoblot analysis and antigen-capture immunoradiometric assay, but both mutant and wild-type derivatives induced antibodies that cross-reacted with wild-type HBsAg. The results emphasise the potential for HBcAg fusion proteins in vaccines by broadening the antibody response in a way that could confer protection against both wild-type and variant forms of HBV. J. Med. Virol. 51:159–166, 1997. © 1997 Wiley-Liss, Inc.     

Morphometric study of hepatocytes containing hepatitis B surface antigen

The development of hepatocellular carcinoma (HCC) is probably related to infection with hepatitis B virus (HBV). Hepatocytes in livers of patients with HCC have been reported to show putative preneoplastic changes such as hyperplasia, dysplasia, or adenomatous regeneration. To determine quantitatively whether these morphologic changes are associated with HBV-infected cells, the authors performed morphometry of hepatitis B surface antigen (HBsAg)-positive hepatocytes in the nontumorous portion of 10 livers with HCC and in 10 livers without HCC. The diameter of nuclei and cytoplasm of HBsAg-positive hepatocytes was measured after demonstration of HBsAg by the peroxidase-antiperoxidase method. As controls, HBsAg-negative hepatocytes in the same liver sections were measured as well as hepatocytes of 20 age-matched HBsAg-negative patients with normal liver or alcoholic cirrhosis. HBsAg-positive hepatocytes exhibited significantly larger nuclei and a higher nucleocytoplasmic ratio than control hepatocytes. In addition, HBsAg-positive cells were often arranged in foci that consisted of two cell populations: hypertrophic (enlarged nuclei and nucleocytoplasmic ratio) and hyperplastic (two-cell-thick plates of small cells with a high nucleocytoplasmic ratio). While precancerous cells have been difficult to identify, these morphologic changes are frequently associated with the development of malignant neoplasia.     

Synthesis and immunogenicity of hepatitis B virus envelope antigen expressed by recombinant vaccinia virus

Summary Five different recombinant vaccinia viruses expressing the envelope antigen of hepatitis B virus (HBsAg) under the control of the P_7·5 promoter were constructed. Cell cultures infected with some of the recombinant viruses synthesized both middle (M) and major surface (S) protein of HBsAg. It was shown that the length of the nontranslated sequence preceding preS2-ATG influenced the extracellular or intracellular HBV antigen distribution and the preS2:S antigen ratio. Some recombinants synthesized an M protein that was enlarged by additional 35 amino acids of preS1 domain and was entirely retained within the infected cells. Antibody responses to the S and preS2 antigens in mice revealed significant differences in the immunogenicity of individual recombinants.     

乙型肝炎病毒表面抗原基因点突变对HBsAg抗原性的影响

目的 研究乙型肝炎病毒表面抗原(HBsAg)常见基因点突变对HBsAg抗原性的影响,了解我国目前常用的HBsAg检测试剂对HBV S基因突变株的检测灵敏性,减少漏检,有效控制乙肝病毒(HBV)感染的传播.方法 构建HBsAg重组野毒株和重组变异株表达质粒,分别将重组野毒株HBsAg表达质粒pSS1adw2及pSS1adr和重组变异株HBsAg表达质粒pSS1adw2-145Arg、pSS1adr-126 Ser和pSS1adr-126 Asn转染COS-7细胞,进行瞬时转染.采用市售HBsAg ELISA检测试剂盒对细胞上清进行抗原性检测.结果 野毒株HBsAg和两种126位变异株HBsAg具有较好的抗原性;145位点突变后、导致HBsAg的抗原性下降.结论 推测是由于145位点变异影响了"a"抗原决定簇的空间结构,从而降低了其与抗-HBs的结合能力.     

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.     

Localization of hepatitis B surface antigen epitopes present on variants and specifically recognised by anti-hepatitis B surface antigen monoclonal antibodies

Small hepatitis B surface antigen (HBsAg) is considered to be the best marker for the diagnosis of Hepatitis B virus infection. However, HBsAg variants with mutations within the "a" determinant may be poorly or not detected by diagnostic assays. Three anti-HBsAg monoclonal antibodies (6H6B6, 27E7F10, and 2G2G10), directed against conformational epitopes, were tested for their ability to detect the wild-type HBsAg as well as variant forms and their respective epitopes were localised on the HBsAg sequence by using the phage-displayed peptide library technology. Whereas 6H6B6 did not detect mutations T123N, S143L, D144A and G145R, 27E7F10 binding was affected by mutations P120T and G145R. In contrast, 2G2G10 reacted strongly with all tested variants including variant with the G145R mutation. Part of the 6H6B6 epitope was located in the major hydrophilic region (MHR) at residues 101-105, the 27E7F10 epitope (residues 214-219) was located near the C-terminal end of the antigen and the 2G2G10 epitope at residues 199-208, within the theoretical fourth transmembrane helix. The 2G2G10 epitope localisation brings information about the HBsAg structure and the validity of established topological models. Finally, 2G2G10 is a valuable tool for HBsAg variant detection that is used as capture phase in a new bioMérieux diagnostic assay, which is currently in development.     

Evaluation of a new rapid test for the combined detection of hepatitis B virus surface antigen and hepatitis B virus e antigen

There are about 350 million chronic hepatitis B virus (HBV) carriers worldwide. A proactive approach to the management of this disease is likely to reduce the morbidity and mortality caused by HBV. This study aimed to evaluate the diagnostic performance of a novel tool for discriminating between infected and noninfected subjects, the hepatitis B sAg/eAg test (Binax Inc., Portland, Maine). The test is designed to rapidly and accurately detect both the HBV surface antigen (HBsAg) and the HBV e antigen (HBeAg). A cohort of 942 subjects was tested. The serum clinical sensitivity of the hepatitis B sAg/eAg test was 99.75 and 96.37% for HBsAg and HBeAg, respectively. Serum clinical specificity was 99.32% for HBsAg and 98.99% for HBeAg. Analytical sensitivity was satisfactory for the purposes of population screening. Visual evaluation showed that the test signals were stable for at least 3 h after the recommended evaluation time. No interference or cross-reactivity was observed with known interfering substances and virologic markers. These results indicate that the hepatitis B sAg/eAg test is well suited to the accurate detection of HBV carriers. In addition to the good clinical specificity and sensitivity of this test, its stability and user-friendly design mean that a correct performance, even under field conditions, is highly likely. Consequently, the hepatitis B sAg/eAg test has the potential to identify subjects who require HBV vaccination (HBsAg(-) and HBeAg(-)) and HBV-infected individuals who might benefit most from antiviral therapy (HBsAg(+) and HBeAg(+)).