人免疫缺陷病毒I型Vif蛋白的原核表达、纯化及单克隆抗体制备

目的：克隆、表达、纯化人免疫缺陷病毒I型（HIV-1）Vif蛋白,制备其单克隆抗体。方法：提取感染了HIV的细胞基因组DNA,PCR扩增vif基因,插入表达载体pET32a,转化大肠杆菌BL21（DE3）获得工程菌株,IPTG诱导蛋白表达,Western印迹鉴定目的蛋白,亲和层析纯化目的蛋白;免疫BALB／c小鼠,制备单克隆抗体。结果：构建了Vif蛋白的原核表达载体vif-pET32a,并在大肠杆菌中获得高表达,目的蛋白以包涵体形式存在;纯化获得高纯度的重组Vif蛋白,蛋白浓度可达0．56mg／mL;建立了抗Vif蛋白单克隆抗体细胞株,制备了腹水,滴度可达1：16×10^6,抗体纯化后保持了活性和特异性。结论：在原核表达系统中表达、纯化了重组Vif蛋白,制备了针对Vif蛋白的单克隆抗体,为研究Vif蛋白的功能和抗原性奠定了基础。     

人突触小体相关蛋白25单克隆抗体的制备及初步鉴定

目的:制备抗人突触小体相关蛋白25(SNAP25)的鼠源单克隆抗体。方法:利用大肠杆菌表达SNAP25蛋白,纯化后免疫BALB/c小鼠制备杂交瘤细胞,筛选针对SNAP25的阳性杂交瘤细胞株,鉴定抗体亚型;用杂交瘤细胞株制备腹水单抗,纯化后利用SDS-PAGE检测抗体纯度。结果:表达并纯化得到纯度大于90%的SNAP25蛋白,免疫小鼠后经2轮筛选得到12株阳性杂交瘤细胞株,其中抗体重链包括IgG1、IgG2型,轻链大部分为κ链;选择具有相对较高抗原结合活性的14号杂交瘤细胞株制备腹水,纯化后得到纯度大于90%的抗体。结论:获得1株高纯度的针对SNAP25的鼠源单克隆抗体,为肉毒毒素的检测奠定了基础。     

抗羊口疮病毒ORFV118蛋白单克隆抗体的制备、鉴定及其应用

制备抗羊口疮病毒118(ORFV118)重组蛋白的单克隆抗体并鉴定其生物学特性。构建ORFV118原核表达重组质粒pET33b-ORFV118,将重组质粒转化大肠杆菌BL21,诱导表达出ORFV118重组蛋白;利用Ni-NTA亲和层析法纯化ORFV118重组蛋白;以纯化蛋白为抗原免疫小鼠,通过杂交瘤技术制备单克隆抗体;利用间接ELISA法、Western blot、免疫组化等方法分别对单抗特异性、效价、亚型以及ORFV118蛋白的功能进行研究。获得了3株稳定分泌单克隆抗体的细胞株,分别命名为1A2,3B5,5D10,它们诱生的小鼠腹水效价分别为110 000,16 400,18 000。其中效价最高的1A2抗体亚型为IgG1,能特异性结合其免疫原蛋白、真核表达产物以及病羊皮肤组织中的ORFV118蛋白。免疫组化结果显示单抗1A2染色局限于皮肤表皮层角化细胞及浸润至皮下组织的炎症细胞,与病毒侵染上皮组织层的特性相符。制备的单抗1A2能特异性识别ORFV118。深入研究单抗1A2将为了解ORFV118的生物学特性,为羊传染性脓疱病的诊断、预防与治疗提供可能和新思路。     

抗GPNMB单克隆抗体的制备及双抗体夹心ELISA方法的建立

目的:制备抗GPNMB单克隆抗体,建立双抗体夹心ELISA检测GPNMB在胶质母细胞瘤中的表达情况.方法:以新鲜胶质母细胞瘤组织为材料,提取总RNA,通过RT-PCR扩增得到GPNMB cDNA序列,经NcoⅠ和XhoⅠ双酶切后,克隆入PET-28a(+)进行原核表达,经蛋白纯化得GPNMB-6× His融合蛋白;以该融合蛋白免疫BALB/c小鼠,淋巴细胞杂交瘤法制备单克隆抗体;采用Western-blot、双抗体夹心ELISA以制备所得的抗GPNMB抗体检测胶质母细胞瘤细胞系U251、U373、SHG44和星形胶质细胞系SVG12中GPNMB的表达.结果:成功构建了GPNMB原核表达载体,获得了GPNMB-6×His重组蛋白;制备得到了G203、F105和M306共3株抗GPNMB的单克隆抗体,腹水ELISA效价分别为1∶8000、1∶8000、1∶5000,抗体亚类分别为IgG2、IgG1和IgG1,进一步实验证实单克隆抗体G203和M306可用于双抗体夹心ELISA检测不同胶质细胞瘤细胞系中GPNMB的表达.结论:成功制备出抗GPNMB单克隆抗体,效价及特异性良好,并证实GPNMB在胶质母细胞瘤细胞系中高表达,为进一步研究GPNMB在胶质母细胞瘤中的作用奠定了基础.     

幽门螺杆菌HP0762蛋白的原核表达纯化及多克隆抗体制备

目的:表达和纯化幽门螺杆菌HP0762蛋白,并制备该蛋白的多克隆抗体。方法:从幽门螺杆菌SS1中经PCR扩增得到了hp0762基因,将其克隆至含有6×His编码序列的原核表达载体pET-28a(+)中,再将重组质粒转化大肠杆菌BL21(DE3),在IPTG诱导下进行蛋白表达;用HiTrap Chelating HP亲和柱纯化重组蛋白,Western印迹进一步鉴定;以纯化后的蛋白为抗原免疫新西兰大耳白兔,制备该蛋白的多克隆抗体;用ELISA和Western印迹检测抗血清。结果:目的蛋白在大肠杆菌BL21(DE3)中获得了可溶性表达,纯化后纯度可达90%以上;制备了针对HP0762重组蛋白的抗血清,抗体ELISA效价为1:256000,Western印迹分析表明该抗体能特异性识别内源性HP0762。结论:完成了HP0762蛋白的原核高效表达与纯化,并制备了其高效价的多克隆抗体,为进一步对其进行疫苗研制与基因功能研究奠定了基础。     

人类博卡病毒(HBoV)非结构蛋白NS1基因的克隆、原核表达及多克隆抗体的制备

目的:克隆、表达、纯化人类博卡病毒(HBoV)非结构蛋白NS1,制备抗NS1多克隆抗体。方法:利用PCR扩增HBoV非结构蛋白NS1基因,将其克隆至pMAL-c2X表达载体上,重组质粒转化大肠杆菌DH10B,IPTG诱导表达。表达的融合蛋白经Amylose Resin亲和层析柱纯化后,免疫新西兰大白兔制备多克隆抗体。用间接ELISA法检测抗体效价。结果:原核表达融合蛋白MBP-NS1,并获得了其多克隆抗体,抗体效价达到1∶32000。结论:在原核表达系统中表达、纯化了融合蛋白,制备抗NS1多克隆抗体,为进一步研究该病毒非结构蛋白基因的转录和翻译机制提供可靠的工具。     

人生长分化因子15的原核表达、纯化与多克隆抗体制备

目的:原核表达并纯化、鉴定人生长分化因子15(GDF-15),制备其多克隆抗体。方法:从人结肠癌细胞系HT29的cDNA扩增出GDF-15基因片段并插入pET-32a(+)原核表达载体,转化大肠杆菌BL21,IPTG诱导表达重组GDF-15,用镍亲和柱纯化,SDS-PAGE、Western印迹鉴定重组蛋白。用纯化的重组GDF-15免疫BALB/c小鼠制备多克隆抗体,鉴定并检测其效价。结果:制备了pET-32a(+)-GDF-15表达载体;经IPTG诱导重组蛋白表达后,采用Ni亲和柱纯化蛋白,并经SDS-PAGE和免疫印迹鉴定;免疫BALB/c小鼠后获得了GDF-15多克隆抗体,ELISA检测抗体效价为1∶100000,并应用于肿瘤细胞的GDF-15检测中。结论:用基因工程和免疫学方法制备了重组人GDF-15及其多克隆抗体,为后续的分子机制和靶向治疗研究奠定了基础。     

1株猪δ冠状病毒N蛋白单克隆抗体制备与鉴定

【背景】猪δ冠状病毒(porcine deltacoronavirus,PDCoV)是一种新发现的猪肠道冠状病毒,主要引起以急性水样腹泻、呕吐和脱水等特征的胃肠道疾病。在PDCo V的4个结构蛋白中,核衣壳蛋白(nucleocapsid protein,N)为高度保守的结构蛋白,在病原诊断方面具有重要意义。【目的】以纯化的重组PDCo VN蛋白为抗原,制备抗N蛋白的单克隆抗体并进行特性鉴定。【方法】利用已构建的p ET-28a-N表达菌,经IPTG诱导表达获得具有免疫原性的重组N蛋白,并将纯化的重组N蛋白免疫BALB/c小鼠制备杂交瘤细胞,经3次亚克隆筛选,选取抗体效价最高的一株杂交瘤细胞注射小鼠腹腔并制备腹水单克隆抗体,利用Protein G亲和层析柱纯化。通过腹水单克隆抗体效价测定、抗体亚型鉴定、Western blot鉴定其特性;利用细胞间接免疫荧光试验、组织石蜡切片荧光试验、免疫组化、流式细胞荧光分选技术鉴定其诊断应用价值。【结果】经筛选后得到一株杂交瘤细胞命名为4E88,其腹水单克隆抗体效价为1:105,亚型为Ig G1型,轻链为κ链,Western blot试验表明该单克隆抗体与重组N蛋白和超速离心纯化的PDCo V全病毒反应形成特异性条带。此外,单克隆抗体4E88可以用于猪δ冠状病毒检测的间接免疫荧光试验、免疫组化染色和流式细胞荧光分选技术。【结论】研究获得的单克隆抗体4E88具有较好的反应性,为后续开展PDCo V鉴定、诊断和N蛋白功能研究等奠定基础。     

大鼠RVLG cDNA的克隆、原核表达和小鼠抗RVLG蛋白多克隆抗体的制备

为了识别大鼠卵巢中的生殖细胞,在原核系统中表达和纯化RVLG蛋白并制备了多克隆抗体.采用RT-PCR方法从大鼠睾丸组织中扩增获得RVLG cDNA片段,然后克隆到pMD19-T载体上进行测序,经双酶切回收目的基因片段后,将其插入到原核表达载体pGEX-4T-1上,转入大肠杆菌BL21(DE3)中诱导表达.纯化后的GST-RVLG融合蛋白免疫昆明(KM)小鼠,最后给小鼠腹腔注射S180细胞制备抗RVLG腹水多克隆抗体.用Western blotting及免疫组织化学法鉴定RVLG腹水多克隆抗体的特异性,间接ELISA法测定该抗体的效价.序列分析表明,所克隆的RVLG cDNA片段比GenBank中报道的大鼠RVLG cDNA(NM_001077647)多60 bp,原因是由于RVLG的可变剪切方式造成的.本研究成功构建了重组表达质粒pGEX-RVLG,且GST-RVLG融合蛋白在大肠杆菌BL21(DE3)中高效表达,表达的目的蛋白占菌体总蛋白的10%以上.制备的抗体可特异性识别RVLG蛋白,其效价达1:20 000.获得的高效价、高特异性的小鼠抗RVLG蛋白腹水多克隆抗体为下阶段研究RVLG的特异性表达奠定了基础.     

沙门菌外膜蛋白D的原核表达及多克隆抗体制备

目的:在大肠杆菌中表达沙门菌外膜蛋白(OMP)D,纯化后制备兔抗OMPD抗体。方法:用PCR方法从鼠伤寒沙门菌中扩增出ompD基因,并插入融合表达载体pET-28a(+)的多克隆位点,构建重组表达质粒pET28a(+)-ompD;以重组质粒转化大肠杆菌BL21(DE3),筛选阳性重组菌株,经IPTG诱导目的蛋白表达,在变性条件下对目的蛋白进行亲和层析纯化;以表达的OMPD蛋白免疫家兔,制备抗OMPD的多克隆抗体并进行鉴定。结果:扩增了ompD基因,测序证实正确后亚克隆于表达载体pET-28a(+)中,经PCR筛选和酶切鉴定获得阳性克隆,经诱导在大肠杆菌中表达出相对分子质量为40×103的目的蛋白并进行纯化;纯化的OMPD免疫家兔后,能有效地刺激特异性抗体的产生,抗血清的效价达到1∶10000以上,且具有良好的特异性。结论:构建ompD基因的原核表达载体,并在大肠杆菌中获得高效表达;制备出兔抗OMPD抗体,效价及特异性均良好,为进一步制备肠黏膜高亲和力疫苗奠定了基础。     

以MyD88 TIR二聚化为靶点的抗炎抑制剂筛选模型的建立

MyD88是IL-1R/TLR受体超家族向细胞内转导胞外信号时募集到受体胞浆尾部的重要接头蛋白．由TIR结构域介导的MyD88分子同源二聚化是它招募到受体胞浆尾部的前提,然后二聚化的MyD88再募集下游信号分子,传递信号,引发促炎基因的表达．本研究旨在建立一种模型,以实现活细胞原位的、基于荧光信号变化的MyD88二聚化抑制物的高通量筛选．我们分别构建了MyD88 TIR与GFP和RFP的融合蛋白表达质粒,瞬时转染HeLa细胞,在488 nm激发光下,转染GFP-MyD88 TIR和RFP-MyD88 TIR细胞,检测到绿色荧光与红色荧光间的共振能量转移(FRET)．而当细胞转染GFP-MyD88 TIR和RFP或RFP-MyD88 TIR和GFP,因TIR二聚化不能实现,FRET效率受到严重影响．实验结果提示,依赖双阳性表达GFP-MyD88 TIR和RFP-MyD88 TIR的细胞株,检测不同化合物对于荧光FRET效率的影响,可以建立MyD88 TIR二聚化抑制药物的筛选模型．此外,我们构建了原核表达质粒,利用纯化的His-MyD88 TIR分别与GST或GST-MyD88 TIR蛋白进行体外结合实验,发现GST-MyD88 TIR(而非GST)可以与His-MyD88 TIR相互结合．结果的差异性提示,利用His-MyD88 TIR和GST-MyD88 TIR体外结合实验分析,可以进一步确定抑制物是否直接阻断了TIR的相互作用．结合真核细胞的荧光FRET阻断结果和原核表达的重组蛋白相互作用分析,可确定MyD88 TIR二聚化的抑制物．利用这一模型可以对商品化的小分子库、自行制备的天然产物组分进行广泛的筛选,从中获得有效抑制MyD88二聚化的化合物,参与对MyD88信号通路依赖的慢性炎症、自身免疫性疾病的药物治疗．     

Mycobacterial infection in MyD88-deficient mice

MyD88 is an adaptor protein that plays a major role in TLR/IL-1 receptor family signaling. To understand the role of MyD88 in the development of murine tuberculosis in vivo, MyD88 knockout (KO) mice aerially were infected with Mycobacterium tuberculosis. Infected MyD88 mice were not highly susceptible to M. tuberculosis infection, but they developed granulomatous pulmonary lesions with neutrophil infiltration which were larger than those in wild-type (WT) mice (P < 0.01). The pulmonary tissue levels of mRNA for iNOS and IL-18 were slightly lower, but levels of mRNA for IL-1 beta, IL-2, IL-4, IL-6, IL-10, IFN-gamma, and TGF-beta were higher in MyD88 KO mice. IFN-gamma, TNF-alpha, IL-1 beta, and IL-12 also were high in the sera of MyD88 KO mice. There were no statistically significant differences in the expression of TNF-alpha, IL-12, and ICAM-1 mRNA between MyD88 KO and WT mice. Thus, MyD88 deficiency did not influence the development of murine tuberculosis. NF-kappa B activity was similar in the alveolar macrophages from the lung tissues of MyD88 KO and WT mice. Also, there may be a TLR2-specific, MyD88-independent IL-1 receptor/TLR-mediated pathway to activate NF-kappa B in the host defense against mycobacterial infection.     

Atg5 regulates formation of MyD88 condensed structures and MyD88-dependent signal transduction

MyD88 is known as an essential adaptor protein for Toll-like receptors (TLRs). Previous studies have shown that transfected MyD88 forms condensed structures in the cytoplasm. However, upon TLR stimulation, there is little formation of endogenous MyD88 condensed structures. Thus, the formation of MyD88 condensed structures is tightly suppressed, but the mechanism and significance of this suppression are currently unknown. Here we show that Atg5, a key regulatory protein of autophagy, inhibits the formation of MyD88 condensed structures. We found that endogenous MyD88 had already formed condensed structures in Atg5-deficient cells and that the formation of condensed structures was further enhanced by TLR stimulation. This suppressive effect of Atg5 may not be associated with autophagic processes because MyD88 itself was not degraded and because TLR stimulation did not induce LC3 punctate formation and LC3 conversion. Immunoprecipitation analysis revealed that Atg5 could interact with MyD88. Furthermore, Atg5 deficiency increased formation of the MyD88–TRAF6 signaling complex induced by TLR stimulation, and it enhanced activation of NF-κB signaling but not MAPKs and Akt. These findings indicate that Atg5 regulates the formation of MyD88 condensed structures through association with MyD88 and eventually exerts a modulatory effect on MyD88-dependent signaling.     

Regulation of MyD88 Aggregation and the MyD88-dependent Signaling Pathway by Sequestosome 1 and Histone Deacetylase 6

MyD88 is an essential adaptor molecule for Toll-like receptors (TLRs) and interleukin (IL)-1 receptor. MyD88 is thought to be present as condensed forms or aggregated structures in the cytoplasm, although the reason has not yet been clear. Here, we show that endogenous MyD88 is present as small speckle-like condensed structures, formation of which depends on MyD88 dimerization. In addition, formation of large aggregated structures is related to cytoplasmic accumulation of sequestosome 1 (SQSTM1; also known as p62) and histone deacetylase 6 (HDAC6), which are involved in accumulation of polyubiquitinated proteins. A gene knockdown study revealed that SQSTM1 and HDAC6 were required for MyD88 aggregation and exhibited a suppressive effect on TLR ligand-induced expression of IL-6 and NOS2 in RAW264.7 cells. SQSTM1 and HDAC6 were partially involved in suppression of several TLR4-mediated signaling events, including activation of p38 and JNK, but they hardly affected degradation of IκBα (inhibitor of nuclear factor κB). Biochemical induction of MyD88 oligomerization induced recruitment of SQSTM1 and HDAC6 to the MyD88-TRAF6 signaling complex. Repression of SQSTM1 and HDAC6 enhanced formation of the MyD88-TRAF6 complex and conversely decreased interaction of the ubiquitin-specific negative regulator CYLD with the complex. Furthermore, ubiquitin-binding regions on SQSTM1 and HDAC6 were essential for MyD88 aggregation but were not required for interaction with the MyD88 complex. Thus, our study reveals not only that SQSTM1 and HDAC6 are important determinants of aggregated localization of MyD88 but also that MyD88 activates a machinery of polyubiquitinated protein accumulation that has a modulatory effect on MyD88-dependent signal transduction.     

MyD88 predicts chemoresistance to paclitaxel in epithelial ovarian cancer

Introduction: Early identification of chemoresistance in patients with ovarian cancer is of utmost importance in order to provide them with the most appropriate therapy. Recently, we described the expression of MyD88 in ovarian cancer cells that were resistant to the cytotoxic agent paclitaxel. In addition to chemoresistance, in MyD88 positive ovarian cancer cells, paclitaxel stimulates growth and production of proinflammatory cytokines. The objective of this study was to determine the correlation of MyD88 expression in primary and recurrent epithelial ovarian cancers with the response to carboplatin and paclitaxel combination chemotherapy. Methods: Tumors are heterogeneous structures that contain different cell populations, thus rendering the identification of specific tumor markers difficult. Using laser capture microdissection, pure cancer cells were isolated from ovarian malignant tumors that were obtained from 20 patients at the time of surgery. The microdissected cells were evaluated for the expression of MyD88, FasL, and XIAP by western blot analysis. Results: Protein expression was observed in samples containing as low as 500 cells. The results were correlated with the clinical course of those patients. It was evident that MyD88 expression in ovarian cancer cells accurately predicts a poor response to paclitaxel chemotherapy as shown by a short progression-free interval and overall survival. Conclusion: We describe for the first time a molecular approach to identify paclitaxel chemoresistance. Toxicity from agents without therapeutic benefit can be avoided by identifying those patients who will not respond to a specific agent. Molecular markers will enable us to design individualized treatments and improve overall survival.     

Contribution of globular death domains and unstructured linkers to MyD88·IRAK-4 heterodimer formation: An explanation for the antagonistic activity of MyD88s

Homotypic interactions of death domains (DD) mediate complex formation between MyD88 and IL-1 receptor-associated kinases (IRAKs). A truncated splice variant of MyD88, MyD88s, cannot recruit IRAK-4 and fails to elicit inflammatory responses. We have generated recombinant DD of MyD88 and IRAK-4, both alone and extended by the linkers to TIR or kinase domains. We show that both MyD88 DD variants bind to the linker-extended IRAK-4 DD and pull-down full-length IRAK-4 from monocyte extracts. By contrast, residues up to Glu¹¹⁶ from the DD-kinase connector of IRAK-4 are needed for strong interactions with the adaptor. Our findings indicate that residues 110-120, which form a C-terminal extra helix in MyD88, but not the irregular linker between DD and TIR domains, are required for IRAK-4 recruitment, and provide a straightforward explanation for the negative regulation of innate immune responses mediated by MyD88s.     

Endotoxin-induced maturation of MyD88-deficient dendritic cells

LPS, a major component of the cell wall of Gram-negative bacteria, can induce a variety of biological responses including cytokine production from macrophages, B cell proliferation, and endotoxin shock. All of them were completely abolished in MyD88-deficient mice, indicating the essential role of MyD88 in LPS signaling. However, MyD88-deficient cells still show activation of NF-kappaB and mitogen-activated protein kinase cascades, although the biological significance of this activation is not clear. In this study, we have examined the effects of LPS on dendritic cells (DCs) from wild-type and several mutant mice. LPS-induced cytokine production from DCs was dependent on MyD88. However, LPS could induce functional maturation of MyD88-deficient DCs, including up-regulation of costimulatory molecules and enhancement of APC activity. MyD88-deficient DCs could not mature in response to bacterial DNA, the ligand for Toll-like receptor (TLR)9, indicating that MyD88 is differentially required for TLR family signaling. MyD88-dependent and -independent pathways originate at the intracytoplasmic region of TLR4, because both cytokine induction and functional maturation were abolished in DCs from C3H/HeJ mice carrying the point mutation in the region. Finally, in vivo analysis revealed that MyD88-, but not TLR4-, deficient splenic CD11c(+) DCs could up-regulate their costimulatory molecule expression in response to LPS. Collectively, the present study provides the first evidence that the MyD88-independent pathway downstream of TLR4 can lead to functional DC maturation, which is critical for a link between innate and adaptive immunity.     

MyD88 plays an essential role in inducing B cells capable of differentiating into antibody-secreting cells after vaccination

We investigated the roles of MyD88, an innate adaptor signaling molecule, in inducing protective humoral immunity after vaccination with influenza virus-like particles (VLPs). MyD88 knockout C57BL/6 mice (MyD88(-/-) mice) vaccinated with influenza VLPs showed significant defects in inducing IgG2a/c isotype antibodies and in generating splenic recall memory B cell responses and antibody-secreting plasma cells in the bone marrow. The protective efficacy of influenza VLP vaccination was lower in MyD88(-/-) mice than in the wild-type mice. Our findings indicate that MyD88-mediated innate signaling pathways are important for effectively inducing primary and boost immune responses, T helper type 1 isotype-switched antibodies, and gamma interferon (IFN-γ)-secreting T cell responses. In particular, the results in this study demonstrated for the first time that MyD88-mediated immune activation is likely an essential pathway for effective generation of long-lived antibody-secreting plasma cells and highly protective immunity after vaccination with influenza VLPs. This study provides insight into mechanisms by which recombinant viral vaccines induce protective immunity via the MyD88-mediated innate immune signaling pathway.