重组分枝杆菌CFP10-ESAT6融合蛋白和CFP32的表达及其抗原性

目的 重组表达结核分枝杆菌CFP10和ESAT 6的融合蛋白及卡介苗（BCG）CFP32,分析其抗原性。 方法 用重组PCR从结核分枝杆菌标准株H37Rv基因组DNA中扩增获得融合基因cfp10-esat6;从BCG基因组DNA中扩增cfp32基因。经克隆和测序分析后,分别亚克隆至表达载体pQE-30和pET-23a(+),在大肠埃希菌BL21中表达重组蛋白,予以纯化、 鉴定,Western blot和间接ELISA分析重组蛋白的抗原性。 结果构建了重组表达质粒pQE30-cfp10-esat6和 pET-cfp32,表达了CFP10-ESAT6融合蛋白和CFP32。CFP10-ESAT6蛋白表达量约占菌体总蛋白的15.2%,纯化后蛋白纯度约为92%,浓度为0.456-g/L;CFP32蛋白表达量约占菌体总蛋白的10.6%,纯化后蛋白纯度约为90%,浓度为0.310-g/L。纯化CFP10-ESAT6融合蛋白和CFP32检测结核病的敏感性分别为85.7%和71.4%,特异性均为100%。 结论 重组表达获得具有良好抗原性的重组融合蛋白CFP10-ESAT6和重组蛋白CFP32。     

结核分枝杆菌Rv2352c基因的克隆表达及其抗原活性鉴定

目的构建含结核分枝杆菌(M.tb)rv2352c基因原核表达载体,经转化E.coli以表达Rv2352c融合蛋白,并研究其抗原性。方法用PCR扩增M.tb rv2352c基因,克隆入pET30a(+)质粒,构建pET30a(+):rv2352c重组质粒,阳性克隆测序验证正确后转化入表达宿主大肠杆菌BL21(DE3),经IPTG诱导Rv2352c蛋白表达。经Ni+-NTA层析柱纯化融合蛋白,通过SDS-PAGE和结核患者血清Western blot进行鉴定。将纯化的重组蛋白分别免疫家兔,制备抗Rv2352c抗血清,抗血清的效价测定采用酶联免疫吸附试验法(ELISA),取兔抗血清与纯化蛋白Rv2352c通过Western blot方法,检测抗体特异性。结果经酶切鉴定和测序分析证实rv2352c原核表达质粒构建正确,SDS-PAGE和Western blot结果显示,在45 kD处呈现单一蛋白条带。用重组蛋白Rv2352c免疫接种后可诱导出高滴度的特异性抗体。纯化蛋白通过Western blot鉴定证实为目的蛋白,有较强的免疫原性。结论成功构建原核表达重组质粒pET30a(+):rv2352c,制备和纯化的Rv2352c融合蛋白具有较好的纯度和生物学功能,为进一步研究结核病的潜在分子标志物奠定基础。     

重组结核分枝杆菌ESAT6-CFP10蛋白对不同分枝杆菌致敏豚鼠的皮试反应研究

目的 研究重组结核分枝杆菌ESAT6-CFP10蛋白对临床常见致病分枝杆菌及常见环境分枝杆菌致敏豚鼠的皮试反应。 方法 以鸟分枝杆菌、胞内分枝杆菌、蟾蜍分枝杆菌、堪萨斯分枝杆菌、海分枝杆菌、瘰疠分枝杆菌、戈登分枝杆菌、苏加分枝杆菌、龟分枝杆菌脓肿亚种、偶发分枝杆菌、草分枝杆菌、微黄分枝杆菌、非洲分枝杆菌、牛分枝杆菌、结核分枝杆菌与卡介菌等16株菌株的活菌菌液分别经腹股沟皮下攻击豚鼠,每组5只,3～4周后,分别皮内注射TB-PPD、PPD-B和重组结核分枝杆菌ESAT6-CFP10蛋白各0.1 ml,于注射后24、48 h观察局部硬结的纵径与横径,根据48 h的反应结果进行判定。 结果 PPD-B对16种分枝杆菌活菌致敏豚鼠的皮试硬结直径均≥5 mm,呈阳性,阳性比例均为5/5;TB-PPD对结核、牛、非洲分枝杆菌和卡介菌等活菌致敏豚鼠的皮试硬结直径均≥5 mm,呈阳性,阳性比例均为5/5;重组结核分枝杆菌ESAT6-CFP10蛋白对结核、牛和非洲分枝杆菌活菌致敏豚鼠的皮试硬结直径均≥5 mm,呈阳性,阳性比例均为5/5;而对鸟、胞内、蟾蜍、堪萨斯、海、瘰疠、戈登、苏加、龟脓、偶发、草、微黄和卡介菌等分枝杆菌活菌、结核分枝杆菌死菌致敏豚鼠的皮试反应均呈阴性,阳性比例均为0/5。 结论 重组结核分枝杆菌ESAT6-CFP10蛋白能提高结核分枝杆菌感染诊断的特异度并能区别结核分枝杆菌是否存活、卡介菌致敏导致的皮试超敏反应。     

腺病毒载体介导的ICOSIg融合基因对实验性自身免疫性心肌炎作用的研究

目的探讨腺病毒载体介导的ICOSIg基因治疗对实验性自身免疫性心肌炎（EAM）的作用。方法将人ICOS胞外域与免疫球蛋白IgGFc段融合,构建ICOSIg融合基因的腺病毒表达载体P—Adeno—ICOSIg。PoeⅠ消化腺病毒载体后转染HEK293细胞,生产表达ICOSIg融合蛋白的腺病毒;构建增强型绿色荧光蛋白腺病毒作为对照。皮下注射猪心肌肌球蛋白诱导Lewis大鼠EAM模型,随机分为4组,分别于免疫当天（第0天）（A组,n=15）和第14天（B组,n=15）通过股静脉注射ICOSIg重组腺病毒,观察共刺激分子融合蛋白对T细胞激活阶段和炎症阶段的作用,C组（n=10）和D组（n=10）分别在第0天和第14天注射表达增强型绿色荧光蛋白（EGFP）的重组腺病毒。另设E组（n=10）未接受免疫的正常对照组。免疫第28天,超声心动图检测后处死动物。HE染色检测心肌炎症浸润程度。Westernblot检测心肌ICOS、ICOSL、B7—1及B7-2蛋白表达。实时定量RT—PCR定量心肌IL-2、IL-4和IFN-γ mRNA水平。结果第28天B组大鼠心功能指标（短轴缩短率：40．6±6．2比26．2±4．6,20．8±5．6,21．7±9．6）、心肌炎症程度较对照组显著改善。Western blot显示B组ICOS、ICOSL及B7—1蛋白表达显著下调,各组间B7-2蛋白表达差异未见统计学意义。B组大鼠心肌组织IFN-γ mRNA表达降低（19．8±7．9比66．6±4．5,79．6±5．9,80．9±5．1）,IL-4 mRNA表达增加（42．3±8．6比19．7±3．8,22．3±9．0,28．3±2．2）,IL-2表达各组间无显著差异,因此B组IFN-γ／IL-4比值显著低于A、C及D组（0．47±0．36比2．91±0．22,1．89±0．42,2．32±0．83）,表明Th细胞因子平衡向Th2方向偏离。结论炎症高峰期以ICOSIg阻断共刺激分子通路能够减轻EAM心肌组织炎症,改善大鼠心脏功能。其机制可能是下调心肌组织局部ICOS、ICOSL和B7—1表达及对炎症性细胞因子的抑制作用。     

重组结核分枝杆菌CFP10-ESAT-6融合蛋白的制备及应用研究

目的 制备重组培养滤液蛋白10和6000早期分泌性抗原靶的融合蛋白(rCFPlO-ESAT-6)，研究其免疫学特性，评价其在结核病血清学诊断中的价值。方法 用基因拼接(Gene SOEing)法扩增lhp-ESAT-6融合基因、并克隆人pQE30质粒，表达、纯化rCFPl0-ESAT-6蛋白，通过Western blot分析其抗原性。建立豚鼠BCG免疫模型和结核分枝杆菌强毒株(H37Rv)感染模型，建立以融合蛋白为抗原的酶联免疫吸附测定(ELISA)法，检测豚鼠血清中的抗结核分枝杆菌抗体，并与以纯化蛋白衍生物(PPD)为抗原的ELISA法比较。结果 重组质粒pQE30-CFPl0-ESAT-6靶基因的测序结果与预计序列(lhp-linker-ESAT-6)完全一致。融合蛋白在DH5α菌中以可溶性非包涵体形式存在，表达量占菌体总蛋白的40％，分子质量为26000，纯化后的蛋白纯度为98％，浓度为1.2g／L。Western blot分析表明，融合蛋白与活动性肺结核患血清、兔抗CFP10血清和兔抗ESAT-6血清都能发生特异性免疫反应。以10只生理盐水处理豚鼠血清的平均吸光度(A)值 2s为正常界限值，以融合蛋白为抗原，11份H37Rv感染豚鼠血清全部呈阳性反应，11份BCG免疫豚鼠血清仅1份呈阳性反应；以PPD为抗原，11份H37Rv感染豚鼠血清全部呈阳性反应，11份BCG免疫豚鼠血清也全部呈阳性反应。结论 pQE30-CFPl0-ESAT-6 DH5α菌能高效表达rCFPl0-ESAT-6融合蛋白，该蛋白兼具CFPl0和ESAT-6两种蛋白的抗原性，能特异性区分豚鼠因H37Rv感染和BCG免疫后产生的抗结核分枝杆菌抗体。本研究为rCFPl0-ESAT-6融合蛋白在结核病血清学诊断中的应用奠定了基础。     

小鼠组氨酰tRNA合成酶与麦芽糖结合蛋白融合基因在大肠杆菌中的表达与鉴定

目的 在大肠杆菌中表达小鼠组氨酰tRNA合成酶(HARS)与麦芽糖结合蛋白(MBP)融合基因,通过亲和层析纯化以获得具有抗原特异性的重组蛋白.方法 提取C57BL/6小鼠肌肉组织总RNA,反转录为cDNA,利用软件设计一对特异性引物,扩增HARS基因上游591对碱基序列.对扩增产物和载体质粒pMALc-5e分别进行双酶切,再用T4连接酶连接得到重组质粒.将其转化大肠杆菌感受态细胞,挑取单克隆培养并鉴定质粒序列.异丙基-β-D硫化吡喃半乳糖苷(IPTG)诱导融合蛋白表达后亲和层析纯化,聚丙烯酰胺凝胶电泳对融合蛋白进行相对分子质量粗鉴定,蛋白印迹法鉴定抗原特异性.结果 重组HARS-MBP融合蛋白基因在大肠杆菌胞质中高效表达,亲和层析纯化后的融合蛋白与预测相对分子质量66 000相符,与抗体具有良好的特异结合能力.结论 小鼠HARS-MBP融合基因能够在大肠杆菌中稳定高效地表达,表达的蛋白具有良好的抗原特异性,为后续炎性肌病的研究提供了基础.     

结核分枝杆菌ESAT6-RpfE亚单位疫苗的构建与免疫原性研究

目的 构建Mtb ESAT6-RpfE（早期分泌抗原靶6-复活促进因子E）的原核表达载体,表达和纯化融合蛋白,并对其免疫原性进行研究。方法 分别以Mtb H37Rv及临床株的基因组为模板,PCR扩增esat6、rpfE基因,依次插入pET30a质粒并在大肠埃希菌BL21中表达纯化ESAT6-RpfE蛋白。采用完全随机的方法将C57BL/6小鼠分组,每组6只,共进行了两次实验,第一次实验分为ESAT6、RpfE、ESAT6 RpfE、PBS、BCG五组,佐剂为二甲基三十六烷基胺（dimethyl dioctyldecyl ammonium bromide,DDA）;第二次实验有ESAT6-RpfE、PBS、BCG三组,佐剂为DPG［DDA+poly(I:C)+明胶］。分别于0、3、6周皮下免疫C57BL/6小鼠。末次免疫8周后,用特异性抗原ESAT6及RpfE刺激,检测其分泌IFN-γ的水平;ELISA检测血清特异性抗体IgG2b、IgG1。结果 PCR扩增的esat6、rpfE基因序列与GenBank报道一致;融合蛋白主要以包涵体形式表达;亚单位疫苗免疫动物能够分泌RpfE特异性IFN-γ的脾淋巴细胞数量［(427.13±100.46)］显著高于PBS组(26.13±22.34;q=7.924,P＜0.001); 分泌ESAT6刺激特异性IFN-γ的脾淋巴细胞数量［(506.50±140.40)］明显高于PBS组(19.25±14.75;q=11.36,P＜0.001)和 BCG组(125.5±46.41;q=8.882, P＜0.001)。ESAT6-RpfE免疫组能诱导产生特异性抗体。结论 成功构建并表达ESAT6-RpfE融合蛋白。此融合蛋白可在C57BL/6小鼠中诱导抗原特异性的免疫应答,可作为新型结核亚单位疫苗的候选疫苗予以进一步研究。     

结核分枝杆菌38kD-16kD融合蛋白克隆表达及血清学诊断价值

目的构建重组结核分枝杆菌38kD-16kD融合蛋白,评价其在结核病血清学诊断方面的价值。方法通过聚合酶链反应扩增获得16kD和38kD基因片段,分别连接到表达载体pET21a中,同时将2片段两次连接到表达载体pET21a中,形成38kD-16kD(3816),16kD, 38kD重组载体;经表达、纯化和复性后,通过Western blot分析,以酶联免疫吸附试验检测184例血清抗体,肺结核患者96例、非结核肺部疾病患者50例,正常对照38例。结果成功构建重组质粒pET21a-3816,表达蛋白经SDS-PAGE后显示相对分子质量约为65kD,重组蛋白经镍柱纯化后,纯度均达90%以上;经Western blotting证实重组蛋白能与结核病患者血清反应;重组蛋白3816血清检测,其敏感性为80.2%(77/96),特异性为90.9%(80/88)。结论成功表达和纯化了3816融合蛋白,其对血清学检测证明重组融合蛋白有希望成为结核病血清学诊断的有效候选者之一。     

Evolutionarily related small viral fusogens hijack distinct but modular actin nucleation pathways to drive cell-cell fusion

Fusion-associated small transmembrane (FAST) proteins are a diverse family of nonstructural viral proteins. Once expressed on the plasma membrane of infected cells, they drive fusion with neighboring cells, increasing viral spread and pathogenicity. Unlike viral fusogens with tall ectodomains that pull two membranes together through conformational changes, FAST proteins have short fusogenic ectodomains that cannot bridge the intermembrane gap between neighboring cells. One orthoreovirus FAST protein, p14, has been shown to hijack the actin cytoskeleton to drive cell-cell fusion, but the actin adaptor-binding motif identified in p14 is not found in any other FAST protein. Here, we report that an evolutionarily divergent FAST protein, p22 from aquareovirus, also hijacks the actin cytoskeleton but does so through different adaptor proteins, Intersectin-1 and Cdc42, that trigger N-WASP–mediated branched actin assembly. We show that despite using different pathways, the cytoplasmic tail of p22 can replace that of p14 to create a potent chimeric fusogen, suggesting they are modular and play similar functional roles. When we directly couple p22 with the parallel filament nucleator formin instead of the branched actin nucleation promoting factor N-WASP, its ability to drive fusion is maintained, suggesting that localized mechanical pressure on the plasma membrane coupled to a membrane-disruptive ectodomain is sufficient to drive cell-cell fusion. This work points to a common biophysical strategy used by FAST proteins to push rather than pull membranes together to drive fusion, one that may be harnessed by other short fusogens responsible for physiological cell-cell fusion.

Aquareovirus and orthoreovirus are two genera of the Reoviridae family of segmented double-stranded RNA viruses that form multinucleated syncytia after infection, which can increase viral spread and pathogenicity (1–4). To drive cell-cell fusion, both aquareovirus and orthoreovirus express a nonstructural, fusion-associated small transmembrane (FAST) protein on the plasma membrane of infected cells. The FAST protein is not required for viral entry, and expression of FAST protein alone is sufficient to cause cells to fuse with naïve neighboring cells, forming large multinucleated syncytium (1, 2, 5–12), confirming they are bona fide cell-cell fusogens. Although they have similar function and topology in the membrane, FAST proteins from aquareovirus and orthoreovirus share minimal sequence identity (13). Based on phylogenetic analysis, they are hypothesized to have evolved from a common, likely nonfusogenic, ancestor 510 million years ago (4, 13, 14). Separate gain-of-function events are believed to have produced fusogenic proteins in both aquareovirus and orthoreovirus, with further divergence or acquisition events resulting in the diversity of FAST proteins found in reoviruses today (13).Aquareovirus and orthoreovirus FAST proteins are single-pass membrane proteins of fewer than 200 residues comprised of a mostly disordered cytoplasmic tail, a transmembrane domain, and a small ectodomain of fewer than 40 residues (1, 2). The membrane-disruptive ectodomains of FAST proteins typically have solvent-exposed hydrophobic residues and/or myristoylation motifs that are necessary for cell-cell fusion (5, 15–17). In contrast to other cell-cell fusogens that fuse membranes by pulling them together using conformational changes in their ∼10 nm-tall ectodomains, the ectodomains of FAST proteins have minimal predicted secondary structure, are unlikely to undergo conformational changes to drive membrane fusion (1, 2), and extend only ∼1 nm above the bilayer (5, 18). How such short fusogens can overcome the ∼2 nm repulsive hydration barrier and larger barrier presented by cell surface proteins to reach and fuse with an opposing membrane (5, 18) has been a long-standing question for FAST proteins and other short cell-cell fusogens, such as myomixer and myomaker that are involved in myoblast fusion (19–22).Recently, we found that the FAST protein from reptilian orthoreovirus, p14, hijacks the host cell actin cytoskeleton to drive cell-cell fusion by forming localized branched actin networks (23). This is accomplished through a c-src phosphorylated tyrosine motif, YVNI, in p14’s disordered cytoplasmic tail that binds to a host adaptor protein, Grb2, which then binds to N-WASP and nucleates branched actin assembly. We hypothesize that this directly couples local actin-generated forces to push p14’s short, fusogenic ectodomain into the opposing cell’s plasma membrane (23). While all FAST family proteins have similarly short ectodomains, it is unclear if this is a general strategy used by other FAST proteins to drive cell-cell fusion.Here, we report that a FAST protein from the divergent aquareovirus, p22, also hijacks the host actin cytoskeleton but does so using a molecular strategy distinct from that of the orthoreovirus FAST protein p14. Instead of binding to Grb2, we find that p22 binds to Intersectin-1 through an SH3 binding motif in its cytoplasmic tail, which binds Cdc42 to activate N-WASP–mediated branched actin assembly. We show that despite minimal sequence identity, the p22 cytoplasmic tail can be functionally swapped with that of p14, suggesting that while the cytoplasmic tails of the two FAST proteins evolved independently, they serve a similar function. By directly coupling the ectodomain to a different actin nucleator, we suggest that actin’s functional role is applying mechanical pressure to a fusogenic ectodomain at the plasma membrane. This biophysical role may be shared across other members of the FAST protein family and could be more generally employed by other cell-cell fusogens.     

结核分枝杆菌RpfA融合蛋白的免疫学和生物学特性的初步研究

目的在大肠杆菌中表达并纯化结核分枝杆菌RpfA融合蛋白,并初步研究其免疫学和生物学特性。方法Rp-fA融合蛋白免疫BALB/c小鼠,ELISA法检测免疫小鼠的体液免疫应答效果。分离小鼠的脾淋巴细胞,MTT法检测淋巴细胞增殖指数,ELISA法检测培养液上清IFN-γ,IL-2含量;MTBH37Rv毒株静脉感染免疫小鼠,测定脾脏细菌负荷。将不同浓度的复性RpfA融合蛋白和特异性多抗加入到MTBH37Ra中,测定H37Ra的生长曲线。结果RpfA融合蛋白免疫小鼠的脾淋巴细胞的增殖指数达到3.57,高于生理盐水对照组的1.27(P<0.05);培养上清中IFN-γ含量为362.99±72.75ng/L,IL-2含量为210.10±20.19ng/L,而生理盐水对照组含量均低于50ng/L(P<0.05)。免疫小鼠脾脏细菌负荷计数为5.57±0.37(log10CFU±S),而生理盐水对照组为6.54±0.22(P<0.05)。RpfA融合蛋白对H37Ra的生长有明显促进作用,而加入特异性多抗后可以抑制RpfA融合蛋白的促生长作用。结论RpfA融合蛋白免疫小鼠可引起体液免疫和保护性细胞免疫,可能作为基因疫苗的候选组分。RpfA融合蛋白对H37Ra生长有明显的刺激作用,可能作为快速培养检验结核分枝杆菌的添加组分。     

GST-hPlk2融合蛋白表达载体的构建及其在原核细胞中的表达

目的 构建GST-hPlk2融合蛋白表达载体,并在原核细胞大肠埃希菌(E.coli)中诱导表达.方法 从人HEK293细胞中提取mRNA,反转录为cDNA.用PCR方法扩增出hPlk2基因全长,通过BamH Ⅰ和Xho Ⅰ酶切位点将其定向插入pGEX-4T-2载体中,构建原核表达质粒pGEX-4T-2-hPlk2,并转化E.coli DH5α,筛选阳性重组子,通过限制性内切酶酶切电泳鉴定和DNA序列测定正确后,转入Ecoli BL21中,经异丙基硫代β-D半乳糖苷大量诱导表达,SDS-PAGE电泳和Western blot鉴定.结果 酶切电泳及测序结果证明,成功构建了原核表达质粒GST-hPlk2,并用Western blot方法证实了GST-hPlk2融合蛋白的表达.结论 成功构建了GST-hPlk2原核表达载体,并证实了其在原核细胞E coli中的表达,为进一步纯化Plk2及研究其结构与功能提供了前提基础.     

人源M2三联体靶抗原BPO-E2融合蛋白的克隆表达与鉴定

目的用基因工程的方法克隆表达抗线粒体抗体二亚型（AMA-M2）的3个靶抗原侧链二氧酸脱氢酶复合体E2（BCOADC-E2）、丙酮酸脱氢酶复合体E2（PDC-E2）、2-氧戊二酸脱氢酶复合体E2（OGDC-E2）及其连接形成的三联体BPO-E2融合蛋白，以用于人原发性胆汁性肝硬化（PBC）的早期发现和临床诊断。方法针对BCOADC-E2、PDC-E2、OGDC-E2的cDNA序列设计引物，从正常人的淋巴细胞中提取RNA，通过反转录PCR方法扩增得到相应的基因片段，经测定序列验证后插入表达载体pET28a（＋），构建重组表达载体pET28a（＋）-BCOADC-E2、pET28a（＋）-PDC-E2、pET28a（＋）-OGDC-E2、pET28a（＋）-BPO-E2，转化大肠杆菌BL21（DE3）后诱导表达蛋白质。表达蛋白经SDS-PAGE、Western-blot等鉴定。结果经核苷酸序列测定和酶切鉴定结果表明，成功地构建了4种重组质粒。IPTG诱导表达后，获得4种融合蛋白。经免疫学鉴定，重组抗原片段具有AMA-M2的免疫原性。结论重组表达的融合蛋白将有利于原发性胆汁性肝硬化（PBC）的实验室诊断。     

Dynamic structure of lipid-bound synaptobrevin suggests a nucleation-propagation mechanism for trans-SNARE complex formation

The synaptic vesicle protein synaptobrevin engages with syntaxin and SNAP-25 to form the SNARE complex, which drives membrane fusion in neuronal exocytosis. In the SNARE complex, the SNARE motif of synaptobrevin forms a 55-residue helix, but it has been assumed to be mostly unstructured in its prefusion form. NMR data for full-length synaptobrevin in dodecylphosphocholine micelles reveals two transient helical segments flanked by natively disordered regions and a third more stable helix. Transient helix I comprises the most N-terminal part of the SNARE motif, transient helix II extends the SNARE motif into the juxtamembrane region, and the more stable helix III is the transmembrane domain. These helices may have important consequences for SNARE complex folding and fusion: helix I likely forms a nucleation site, the C-terminal disordered SNARE motif may act as a folding arrest signal, and helix II likely couples SNARE complex folding and fusion.     

The Viral Class II Membrane Fusion Machinery: Divergent Evolution from an Ancestral Heterodimer

A key step during the entry of enveloped viruses into cells is the merger of viral and cell lipid bilayers. This process is driven by a dedicated membrane fusion protein (MFP) present at the virion surface, which undergoes a membrane–fusogenic conformational change triggered by interactions with the target cell. Viral MFPs have been extensively studied structurally, and are divided into three classes depending on their three-dimensional fold. Because MFPs of the same class are found in otherwise unrelated viruses, their intra-class structural homology indicates horizontal gene exchange. We focus this review on the class II fusion machinery, which is composed of two glycoproteins that associate as heterodimers. They fold together in the ER of infected cells such that the MFP adopts a conformation primed to react to specific clues only upon contact with a target cell, avoiding premature fusion in the producer cell. We show that, despite having diverged in their 3D fold during evolution much more than the actual MFP, the class II accompanying proteins (AP) also derive from a distant common ancestor, displaying an invariant core formed by a β-ribbon and a C-terminal immunoglobulin-like domain playing different functional roles—heterotypic interactions with the MFP, and homotypic AP/AP contacts to form spikes, respectively. Our analysis shows that class II APs are easily identifiable with modern structural prediction algorithms, providing useful information in devising immunogens for vaccine design.     

融合蛋白胸腺素α1-干扰素α抗乙型肝炎病毒活性的实验研究

目的观察融合蛋白胸腺素α1-干扰素α(TA1-IFN)体外抗乙型肝炎病毒(HBV)作用,并与胸腺素α1、干扰素α两者联合(TA1+IFN)应用的体外抗HBV作用进行比较。方法HepG22.2.15细胞接种后24h,换用含5种不同浓度(8000、4000、2000、1000、500U／ml)药物的培养基,37℃、体积分数5％CO2条件下培养,每3d换用原浓度含药培养液1次,并于第6天收集培养液,用Abbott诊断试剂盒,分别检测不同组药物作用后上清液中乙型肝炎表面抗原(HBsAg)、乙型肝炎e抗原(HBeAg)的含量,并计算其抑制率;同时用四甲基偶氮唑盐比色分析法检测不同组药物对HepG22.2.15细胞的细胞毒性作用。结果TA1-IFN体外对HBsAg、HBeAg的抑制率与药物浓度呈剂量依赖关系,并且在药物浓度达8000U／ml后趋于稳定,此时TA1-IFN对HBsAg、HBeAg抑制率分别为72.2％±0.8％、60.4％±1.1％,细胞存活率为85.2％±2.0％;而相应浓度的TA1-IFN对HBsAg、HBeAg抑制率为40.0％±0.7％、34.5％±3.2％,细胞存活率为70.0％±1.9％,两者HBsAg、HBeAg抑制率及细胞存活率比较差异均有统计学意义(P值均<0.05)。结论融合蛋白TA1-IFN体外具有良好的抗HBV作用,其体外抗HBV活性比TA1-IFN联合应用强,且细胞毒性比TA1+IFN联合应用时小,本实验为融合蛋白TA1-IFN的临床研究提供了重要的理论     

戊型肝炎病毒ORF3融合蛋白对L02细胞增殖和凋亡的影响

目的检测ORF3融合蛋白对L02细胞增殖与凋亡的影响。方法将重组质粒ORF3-pEGFP和ORF3-pXF2RH脂质体法转染L02细胞,用MTT比色法测定细胞增殖情况,用流式细胞仪碘化丙啶染色法检测细胞周期和细胞凋亡情况。结果转染重组质粒的L02细胞自第4d开始,明显增殖(P<0.05);L02细胞凋亡率由转染前的1.41%分别下降为0.83%和0.88%,差异有统计学意义(P<0.05)。结论戊型肝炎ORF3融合蛋白可减少L02细胞凋亡,而使L02增殖速度增加(P<0.05)。     

Structure of a core fragment of glycoprotein H from pseudorabies virus in complex with antibody

Compared with many well-studied enveloped viruses, herpesviruses use a more sophisticated molecular machinery to induce fusion of viral and cellular membranes during cell invasion. This essential function is carried out by glycoprotein B (gB), a class III viral fusion protein, together with the heterodimer of glycoproteins H and L (gH/gL). In pseudorabies virus (PrV), a porcine herpesvirus, it was shown that gH/gL can be substituted by a chimeric fusion protein gDgH, containing the receptor binding domain (RBD) of glycoprotein D fused to a truncated version of gH lacking its N-terminal domain. We report here the 2.1-Å resolution structure of the core fragment of gH present in this chimera, bound to the Fab fragment of a PrV gH-specific monoclonal antibody. The structure strongly complements the information derived from the recently reported structure of gH/gL from herpes simplex virus type 2 (HSV-2). Together with the structure of Epstein-Barr virus (EBV) gH/gL reported in parallel, it provides insight into potentially functional conserved structural features. One feature is the presence of a syntaxin motif, and the other is an extended “flap” masking a conserved hydrophobic patch in the C-terminal domain, which is closest to the viral membrane. The negative electrostatic surface potential of this domain suggests repulsive interactions with the lipid heads. The structure indicates the possible unmasking of an extended hydrophobic patch by movement of the flap during a receptor-triggered conformational change of gH, exposing a hydrophobic surface to interact with the viral membrane during the fusion process.     

日本血吸虫重组线粒体相关蛋白免疫学活性鉴定

分子筛进一步纯化并复性的融合蛋白均能刺激家兔产生特异性抗体 ,粗提包涵体蛋白免疫家兔 ,血清抗体滴度为 1∶2 5 6 0 0 ,复性蛋白及经分子筛纯化的蛋白免疫的家兔血清抗体滴度均为 1∶5 12 0 0 ,Westernblot结果显示 ,粗提包涵体蛋白、复性蛋白及经过分子筛进一步纯化并复性的蛋白均能被重感染兔血清和rSj338/2 6GST特异性免疫兔血清所识别。攻击实验中 ,粗提包涵体蛋白和经分子筛纯化的蛋白分别可诱导小鼠产生 2 7.8% (P <0 .0 1)和 30 .4 % (P <0 .0 1)的减虫率 ,4 0 .4 % (P <0 .0 1)和 4 3.5 % (P <0 .0 1)肝总减卵率。粗提包涵体蛋白中rSj338和经分子筛纯化的蛋白中rSj338分别可诱导小鼠产生 13.9% (P <0 .0 5 )和 2 0 .0 % (P <0 .0 5 )的减虫率 ,30 .0 % (P <0 .0 1)和 4 1.7% (P <0 .0 1)肝总减卵率。结论　获得的日本血吸虫线粒体相关的重组融合蛋白(rSj338/2 6GST)具有良好的免疫学活性 ,重组融合蛋白 (rSj338/2 6GST)及rSj338均可诱导宿主抗血吸虫感染的部分保护力。     

人新的生长激素异形体基因的克隆及其在大肠杆菌中的表达

目的　构建含新的生长激素异形体 (GHv)基因全长编码区的pGEM TEasy质粒和GHv 谷胱甘肽转硫酶 (GST)融合蛋白的表达质粒并在大肠杆菌表达出其融合蛋白。方法　采用克隆和亚克隆技术构建GHv GST融合基因的表达质粒 ,转化大肠杆菌BL2 1并用异丙基硫代半乳糖苷 (IPTG)诱导其表达GHv GST融合蛋白 ,谷胱甘肽 Sepharose 4B纯化试剂盒纯化融合蛋白。 结果　含GHv GST融合基因表达质粒的大肠杆菌表达出相对分子质量约 43 0 0 0的GHv GST融合蛋白 ,SDS PAGE结果显示纯化的融合蛋白为单一条带。结论　成功构建成GHv GST融合基因的表达质粒并且GHv GST融合蛋白在大肠杆菌BL2 1中有高表达。上述工作为制备多抗 ,深入研究GHv基因的功能奠定了基础。     

HEV ORF3真核表达载体的构建、鉴定和真核表达

目的构建表达戊型肝炎病毒(HEV)ORF3-pXF2RH融合蛋白的真核表达载体;获得重组质粒稳定转染的L02细胞系。方法利用PCR技术从HEV基因组中扩增出ORF3基因片断,HindⅢ/EcolⅠ双酶切后连接到经同样酶切的pXF2RH真核表达载体,转化DH5α菌株感受态细胞,获得阳性重组质粒ORF3-pXF2RH。将阳性克隆用脂质体法转染L02细胞系,G418筛选抗性克隆,SDS-PAGE、Western blot分析鉴定ORF3-pXF2RH融合蛋白的表达。结果真核表达质粒转染L02细胞,SDS-PAGE显示在28.5kD左右蛋白表达量明显高于对照组,Western blot在28.5kD左右有一条强的棕色条带。结论成功构建ORF3-pXF2RH真核表达质粒,在L02细胞表达融合蛋白,为进一步研究该蛋白生物学功能奠定了基础。