人呼吸道合胞体病毒疫苗的研究进展

人呼吸道合胞体病毒(respiratory syncytial virus,RSV)是导致全球婴幼儿细支气管炎及肺炎的主要致病原,造成严重的社会负担.目前还无上市预防RSV感染的疫苗.随着科技的不断发展,研究者已研发了许多不同类型的RSV疫苗,包括弱毒活疫苗、嵌合体疫苗、亚单位疫苗、病毒样颗粒疫苗及纳米颗粒疫苗.本文就...     

人呼吸道合胞病毒蛋白F1片段在大肠杆菌中的表达及纯化

目的在大肠杆菌中表达人呼吸道合胞病毒(Respiratory syncytial virus,RSV)F1蛋白主要抗原表位集中的137～523 aa片段,并对其进行纯化,检测其免疫原性。方法采用RT-PCR扩增RSV F1基因片段,与pThioHisA载体连接,构建重组表达质粒pThioHisA-RSV F1,转化大肠杆菌Top10,IPTG诱导表达,表达产物经SDS-PAGE分析;表达的融合蛋白经稀释复性、离子交换及亲和层析纯化后,进行SDS-PAGE及Western blot分析;将纯化的融合蛋白RSVF1经皮下多点注射分别免疫ICR小鼠,实验分为3组:RSV F1无佐剂组(RSV F1,50μg/只)、RSV F1佐剂组(50μg RSV F1+5μg nOMV佐剂)和阴性对照组(PBS,100μl/只),于第3周加强免疫1次,第4周尾静脉采血,分离血清,采用间接ELISA法检测其免疫原性。结果经双酶切鉴定及DNA测序证明重组表达质粒pThioHisA-RSV F1构建正确;表达的融合蛋白相对分子质量约56 000,主要以包涵体形式表达,表达量约占细胞总蛋白的36%;纯化的融合蛋白纯度可达95%,并可与RSV-F1多克隆抗体发生特异性抗原抗体反应;与阴性对照组相比,RSV F1免疫的小鼠血清特异性IgG水平明显提高(P<0.05)。结论已成功地在大肠杆菌中高效表达了RSV F1片段,纯化的融合蛋白在小鼠体内具有良好的免疫原性,为进一步研究RSV F蛋白亚单位疫苗奠定了基础。     

穿膜肽HIV-TAT与呼吸道合胞病毒G蛋白片段G1及CTL表位融合蛋白的表达及纯化

目的在大肠杆菌中表达含穿膜肽HIV-TAT与呼吸道合胞病毒(RSV)G蛋白片段G1及CTL表位的融合蛋白,并进行纯化。方法以质粒pET-G1F/M2为模板,扩增含TAT、RSVG蛋白片段G1和CTL表位F/M2的融合基因片段,与原核表达质粒pET-His连接,构建融合表达质粒pET-TAT-G1F/M2,转化E.coli BL21(DE3)plysS进行诱导表达,采用Ni2+螯合亲和层析法纯化经尿素变性的包涵体,梯度透析复性纯化的目的蛋白,并进行Westernblot鉴定。结果在E.coli中可高效表达重组蛋白TAT-G1F/M2,表达量占菌体总蛋白的30%以上,目的蛋白主要存在于包涵体中。经变性、纯化、复性可获得高纯度(>95%)特异性的TAT-G1F/M2蛋白。结论已在大肠杆菌中成功表达了融合蛋白TAT-G1F/M2,为进一步进行RSV体内体外免疫学研究奠定了基础。     

表达呼吸道合胞病毒F蛋白的新城疫重组病毒的构建及其免疫原性

目的利用新城疫病毒(Newcastle disease virus,NDV)反向遗传系统构建表达呼吸道合胞病毒(respiratory syncytial virus,RSV)F蛋白的重组病毒,并以BALB/c小鼠为动物模型,评价其免疫原性。方法在已建立的NDV反向遗传系统的基础上,将RSV F基因插入NDV全长cDNA克隆中,构建并拯救获得表达RSV F蛋白的重组病毒rLS/RSV-F。采用间接免疫荧光(indirect immunoinfluscent assay,IFA)法鉴定RSV F蛋白的表达;以HA、病毒半数鸡胚感染量(50%infective dose,EID50)、半数组织感染量(50%tissue infectious dose,TCID50)及生长曲线等生物学指标对其生物学特性进行鉴定;将rLS/RSV-F滴鼻免疫BALB/c小鼠,于免疫后第49天经眼眶后静脉丛采血,分离血清,ELISA法检测IgG抗体效价,中和试验检测中和抗体效价。结果成功拯救表达RSV F蛋白的NDV重组病毒rLS/RSV-F,具有与亲本病毒相似的感染能力及生长动力学特性;rLS/RSV-F可刺激小鼠机体产生较高水平的针对RSV F蛋白的特异抗体及RSV中和抗体,与亲本病毒对照组相比,差异均有统计学意义(P <0. 05)。结论成功拯救了表达RSV F蛋白的NDV重组病毒,并通过动物实验证明重组病毒rLS/RSV-F具有较好的免疫原性,为RSV疫苗的研发提供了新思路。     

快速细胞培养法在呼吸道合胞病毒感染早期诊断中的应用

目的建立检测呼吸道合胞病毒(RSV)的快速细胞培养法,并应用于呼吸道合胞病毒感染的早期诊断。方法采用自制的抗RSV的单克隆抗体,经快速细胞培养法和直接涂片法检测165份急性下呼吸道感染的婴幼儿鼻咽分泌物及咽拭子中RSV,并与病毒分离培养比较,再将自制试剂盒与进口呼吸道病毒荧光检测试剂盒检测结果进行比较,探讨其临床实用性。结果57份咽拭标本中,1份快速细胞培养法及直接涂片法检测均为阳性,阳性率1.8%,未分离到病毒。108份鼻咽分泌物中,快速细胞培养法检出21份阳性,阳性率19.4%。直接涂片法检测出14份阳性,阳性率13%,病毒分离培养法检出阳性12份,阳性率11%。快速细胞培养法与其他两种方法相比,阳性检出率差异有显著意义。自制试剂盒与进口试剂盒检出40份鼻咽分泌物标本,阳性率均为35%。结论将直接涂片法与快速细胞培养法同时应用于RSV感染的早期诊断,既能及时提供检测结果,又能提高诊断的敏感性,是对RSV感染进行早期诊断的实用方法。     

呼吸道合胞病毒培养及其病毒滴度检测方法的建立

目的确定呼吸道合胞病毒(respiratory syncytial virus,RSV)培养条件,筛选病毒保护剂配方,并建立检测病毒滴度的微量细胞病变方法。方法分别将Hep2、Vero和293R细胞以0.01 MOI接种RSV,选择病毒培养细胞基质;将RSV分别以0.005和0.02 MOI接种Hep2细胞,在4~9 d收获病毒液,检测病毒滴度,确定最佳MOI及病毒收获时间;将6种配方病毒保护剂分别加至病毒液中,反复冻融7次,检测病毒滴度,筛选最佳配方;将病毒分别在33和37℃条件下滴定,第7、9天判定结果,确定微量细胞病变方法的培养温度和判定时间。结果确定病毒培养细胞基质为Hep2细胞,以0.02 MOI RSV接种后,37℃培养7~9 d收获病毒液;配方1(0.1%人血白蛋白)为最佳病毒保护剂配方;微量细胞病变法的实验条件为37℃滴定,7 d判定结果。结论建立了稳定可靠的呼吸道合胞病毒培养及病毒滴度检测方法。     

呼吸道合胞病毒G蛋白研究进展

呼吸道合胞病毒G蛋白是该病毒的黏附蛋白,亚型间抗原结构高度变异,在病毒感染和诱导保护性免疫方面起到重要作用。本文对呼吸道合胞病毒G蛋白的结构、功能、免疫表位、CX3C模序及疫苗研制等作一综述。     

呼吸道合胞病毒空斑检测方法的建立及应用

目的建立呼吸道合胞病毒(RSV)空斑检测方法,并用于病毒滴度的定量。方法将不同稀释度的RSVA2株病毒液分别接种于Hep-2细胞单层,加0.6%营养琼脂糖覆盖,培养6d后用10%甲醛固定。去除覆盖层,0.05%中性红染色,按文献报道的方法进行空斑计数。建立空斑法测定RSV滴度的标准曲线,并验证空斑法的准确性及精密性,应用建立的空斑法检测RSV感染BALB/c小鼠肺组织中的RSV滴度。结果RSVA2株感染的Hep-2细胞出现典型的空斑,直径约1～3mm,形态呈圆形或类圆形。空斑法的最低检测限为3.4×101PFU/ml,线性关系良好,相关系数r=0.999996,准确性及精密性均良好。RSV感染的BALB/c小鼠肺组织标本均出现数量不等的空斑。结论所建立的RSV空斑测定方法敏感、准确,能稳定地对病毒滴度进行定量测定,为进一步研究RSV的感染性和免疫原性奠定了基础。     

人呼吸道合胞病毒适应株筛选及其生物学特性

目的建立在Vero细胞上低温传代的人呼吸道合胞病毒(human respiratory syncytial virus,HRSV)适应株,并分析其生物学特性。方法从155份肺炎儿童痰样中经PCR、测序鉴定出14株RSV,将其在Vero细胞上37℃传代第1次收获的病毒记为野毒株(wild-type,WT),通过逐步降低培养温度的方法在Vero细胞传代获得1株适应株(adapted-strain,AS)KM516-AS。将RSV适应株感染A549细胞后,分别至37、25、32和39℃培养,测定其冷适应性和温度敏感性。分别将RSV适应株及其对应的野毒株KM516-WT经鼻腔免疫小鼠,于免疫后第8天,取肺组织制作病理切片,显微镜下观察病变程度;取鼻甲和右肺匀浆组织,制备上、下呼吸道匀浆液,测定上、下呼吸道病毒滴度;于免疫后第13天,经小鼠尾部静脉采血,分离血清,于免疫后第14天,取肺组织制备匀浆液,采用ELISA法测定总抗体滴度,病毒中和试验法测定中和抗体滴度。结果 RSV野毒株KM516-WT的适应温度范围较广,4个不同温度下的病毒滴度变化不大;RSV适应株KM516-AS的适应温度范围较窄,25℃时的病毒滴度最高,随着温度的升高,病毒滴度逐渐降低,且仅有温度敏感性而无冷适应性。野毒株组小鼠肺部呈暗褐色,无严重的实质化,且肺泡和毛细血管中有明显的淋巴浸润;适应株组小鼠肺泡和毛细血管中淋巴浸润较少。适应株在体内的复制水平低于野毒株,并同野毒株一样具有较好的免疫原性。结论获得1株RSV适应株,并具有一定的减毒效果。     

呼吸道合胞病毒F1蛋白截短体(F_(212-489))的原核表达及纯化

目的原核表达并纯化呼吸道合胞病毒(respiratory syncytial virus,RSV)F1蛋白截短体(F212-489)。方法从质粒p MD-18T-f中PCR扩增截短f1基因(f212-489),经TA克隆测序正确后,将目的片段插入原核表达载体p ET-28a,构建重组表达质粒p ET-28a-f212-489,转化大肠埃希菌BL21(DE3),IPTG诱导表达。表达的重组蛋白经镍离子亲和层析纯化后,进行Western blot鉴定。结果重组表达质粒p ET-28a-f212-489经双酶切鉴定构建正确;表达的重组蛋白相对分子质量约为30 000,主要以包涵体形式表达,表达量约占菌体总蛋白的10%;纯化的重组蛋白纯度为85%,可与羊抗RSV多克隆抗体特异性结合。结论成功表达了RSV F1蛋白截短体(F212-489),纯化的重组蛋白反应原性良好,为更好地研究RSV的免疫机理及通过基因工程方法研制特定部位的亚单位或多肽疫苗奠定了基础。     

Mutation in the CX3C Motif of G Protein Disrupts Its Interaction with Heparan Sulfate: A Calorimetric,Spectroscopic, and Molecular Docking Study

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in children and infants. To date, there is no effective vaccine available against RSV. Heparan sulfate is a type of glycosaminoglycan that aids in the attachment of the RSV to the host cell membrane via the G protein. In the present study, the effect of amino acid substitution on the structure and stability of the ectodomain G protein was studied. Further, it was investigated whether mutation (K117A) in the CX3C motif of G protein alters the binding with heparan sulfate. The point mutation significantly affects the conformational stability of the G protein. The mutant protein showed a low binding affinity with heparan sulfate as compared to the wild-type G protein, as determined by fluorescence quenching, isothermal titration calorimetry (ITC), and molecular docking studies. The low binding affinity and decreased stability suggested that this mutation may play an important role in prevention of attachment of virion to the host cell receptors. Collectively, this investigation suggests that mutation in the CX3C motif of G protein may likely improve the efficacy and safety of the RSV vaccine.     

Inhibition of Respiratory Syncytial Virus Infection by Small Non-Coding RNA Fragments

Respiratory syncytial virus (RSV) causes acute lower respiratory tract infection in infants, immunocompromised individuals and the elderly. As the only current specific treatment options for RSV are monoclonal antibodies, there is a need for efficacious antiviral treatments against RSV to be developed. We have previously shown that a group of synthetic non-coding single-stranded DNA oligonucleotides with lengths of 25–40 nucleotides can inhibit RSV infection in vitro and in vivo. Based on this, herein, we investigate whether naturally occurring single-stranded small non-coding RNA (sncRNA) fragments present in the airways have antiviral effects against RSV infection. From publicly available sequencing data, we selected sncRNA fragments such as YRNAs, tRNAs and rRNAs present in human bronchoalveolar lavage fluid (BALF) from healthy individuals. We utilized a GFP-expressing RSV to show that pre-treatment with the selected sncRNA fragments inhibited RSV infection in A549 cells in vitro. Furthermore, by using a flow cytometry-based binding assay, we demonstrate that these naturally occurring sncRNAs fragments inhibit viral infection most likely by binding to the RSV entry receptor nucleolin and thereby preventing the virus from binding to host cells, either directly or via steric hindrance. This finding highlights a new function of sncRNAs and displays the possibility of using naturally occurring sncRNAs as treatments against RSV.     

Nuclear Transport of Respiratory Syncytial Virus Matrix Protein Is Regulated by Dual Phosphorylation Sites

Respiratory syncytial virus (RSV) is a major cause of respiratory infections in infants and the elderly. Although the RSV matrix (M) protein has key roles in the nucleus early in infection, and in the cytoplasm later, the molecular basis of switching between the nuclear and cytoplasmic compartments is not known. Here, we show that protein kinase CK2 can regulate M nucleocytoplasmic distribution, whereby inhibition of CK2 using the specific inhibitor 4,5,6,7-tetrabromobenzo-triazole (TBB) increases M nuclear accumulation in infected cells as well as when ectopically expressed in transfected cells. We use truncation/mutagenic analysis for the first time to show that serine (S) 95 and threonine (T) 205 are key CK2 sites that regulate M nuclear localization. Dual alanine (A)-substitution to prevent phosphorylation abolished TBB- enhancement of nuclear accumulation, while aspartic acid (D) substitution to mimic phosphorylation at S95 increased nuclear accumulation. D95 also induced cytoplasmic aggregate formation, implying that a negative charge at S95 may modulate M oligomerization. A95/205 substitution in recombinant RSV resulted in reduced virus production compared with wild type, with D95/205 substitution resulting in an even greater level of attenuation. Our data support a model where unphosphorylated M is imported into the nucleus, followed by phosphorylation of T205 and S95 later in infection to facilitate nuclear export and cytoplasmic retention of M, respectively, as well as oligomerization/virus budding. In the absence of widely available, efficacious treatments to protect against RSV, the results raise the possibility of antiviral strategies targeted at CK2.     

Modelling the structure of the fusion protein from human respiratory syncytial virus

The fusion protein of respiratory syncytial virus (RSV-F) isresponsible for fusion of virion with host cells and infectionof neighbouring cells through the formation of syncytia. A three-dimensionalmodel structure of RSV-F was derived by homology modelling fromthe structure of the equivalent protein in Newcastle diseasevirus (NDV). Despite very low sequence homology between thetwo structures, most features of the model appear to have highcredibility, although a few small regions in RSV-F whose secondarystructure is predicted to be different to that in NDV are likelyto be poorly modelled. The organization of individual residuesidentified in escape mutants against monoclonal antibodies correlateswell with known antigenic sites. The location of residues involvedin point mutations in several drug-resistant variants is alsoexamined.     

Progressive Changes in Inflammatory and Matrix Adherence of Bronchial Epithelial Cells with Persistent Respiratory Syncytial Virus (RSV) Infection (Progressive Changes in RSV Infection)

In addition to the acute manifestations of respiratory syncytial virus (RSV), persistent infection may be associated with long-term complications in the development of chronic respiratory diseases. To understand the mechanisms underlying RSV-induced long-term consequences, we established an in vitro RSV (strain A2) infection model using human bronchial epithelial (16HBE) cells that persists over four generations and analyzed cell inflammation and matrix adherence. Cells infected with RSV at multiplicity of infection (MOI) 0.0067 experienced cytolytic or abortive infections in the second generation (G2) or G3 but mostly survived up to G4. Cell morphology, leukocyte and matrix adherence of the cells did not change in G1 or G2, but subsequently, leukocyte adherence and cytokine/chemokine secretion, partially mediated by intercellular adhesion molecule-1 (ICAM-1), increased drastically, and matrix adherence, partially mediated by E-cadherin, decreased until the cells died. Tumor necrosis factor-α (TNF-α) secretion was inhibited by ICAM-1 antibody in infected-16HBE cells, suggesting that positive feedback between TNF-α secretion and ICAM-1 expression may be significant in exacerbated inflammation. These data demonstrate the susceptibility of 16HBE cells to RSV and their capacity to produce long-term progressive RSV infection, which may contribute to inflammation mobilization and epithelial shedding.     

Modulation of respiratory syncytial virus-induced prostaglandin E<Subscript>2</Subscript> production by n−3 long-chain polyunsaturated fatty acids in human respiratory epithelium

Infection with respiratory syncytial virus (RSV) results in substantial infant morbidity and has been associated with the subsequent development of childhood asthma. Inflammatory mediators produced by both the epithelium and tissue leukocytes during RSV infection stimulate the release of chemotactic factors by the respiratory epithelium and the subsequent influx of inflammatory cells, predominantly neutrophils. We investigated the production of inflammatory mediators [prostaglandin E₂ (PGE₂), interleukin (IL)-1β, tumor necrosis factor α] and chemokines [IL-8, RANTES (regulation on activation, normal T cell expressed and secreted)] by alveolar epithelial cells in response to RSV infection. Infection of a human alveolar epithelial transformed cell line (A549 cells) with live RSV substantially increased production of PGE₂, IL-8, and RANTES. By altering cell membrane FA through incorporation of the long-chain PUFA (LCPUFA) arachidonic acid, EPA, and DHA, we were subsequently able to significantly modulate PGE₂ production by the infected epithelium. Because of the dynamic nature of the effects of PGE₂ on lung function, regulation of this prostaglandin during RSV infection by n−3 LCPUFA has the potential to significantly alter the disease process.