水稻草矮病毒血清学和分子检测方法的比较

将间接ＥＬＩＳＡ、非放射性分子杂交和ＲＴ－ＰＣＲ三种方法应用于水稻草矮病毒（ＲＧＳＶ）的检测。结果表明,利用自制的融合蛋白ＧＳＴ－ＮＣ的抗血清检测ＲＧＳＶ的灵敏度为１ｍｇ鲜重的病株叶片或８４ｎｇ提纯病毒,利用地高辛（ＤＩＧ）标记的ＤＮＡ探针ＮＣ的点杂交方法检测ＲＧＳＶ的灵敏度为５０μｇ病叶或６ｎｇ病毒,而ＲＴ－ＰＣＲ的检测灵敏度则为１０μｇ病叶或２ｎｇ的病毒,对上述三种方法的灵敏度和可操作性也进行     

液相杂交快速检测特异DNA

检测特异DNA片段的方法中,传统Southern blot技术由于其高度可重复性及能够显示条带大小的特性,一直是DNA检测的“黄金标准”.但是杂交时间长,步骤复杂,放射性污染等问题亟待解决.为了简化Southern blot,研究使用了一种液相杂交快速检测DNA的方法,即使用异硫氰酸荧光素(FITC)标记的dUTP掺入探针后,在溶液中与待检测DNA样本42℃下杂交,然后琼脂糖凝胶电泳检测荧光杂交信号.利用质粒为模板,优化了探针制作、杂交液组成、杂交时间和温度等参数.在FITC-dUTP∶ dTTP比例为1∶3、模板质粒浓度为50μg、1×杂交缓冲液(25 mmol/LTris,10mmol/L EDTA,8mmol/L Nacl,PH =8.0)中95℃变性5～9 min和42℃杂交3h的实验条件下,可检出1.2μg的质粒,探针灵敏度为7.3 ng/μl.这种方法不需要转膜,曝光,大大节约了时间,简化了操作,荧光检测也为该方法同时检测多色样本提供了可能,可广泛应用于核酸检测.     

SYBR Green Ⅰ荧光定量RT-PCR检测埃博拉病毒方法的建立

为了建立一种快速准确的检测埃博拉病毒(EBOV)亚型的方法。本研究根据GenBank中公布的EBOV NP基因序列,通过设计引物和优化反应条件,建立了一种SYBR GreenⅠ荧光定量RT-PCR检测方法检测EBOV。以体外转录的EBOV RNA为模板进行试验,该方法检测的灵敏度可以达到1.0×102个拷贝/μL,检测范围达到9个数量级为102～1010,可检测5种亚型EBOV。建立的方法对马尔堡病毒(MARV)、登革病毒(DENV)、新疆出血热病毒(XHFV)、乙型脑炎病毒(JEV)、流感病毒(H1N1和H3N2)和猪繁殖和呼吸综合征病毒(PRRSV)E基因组RNA无非特异性扩增。本文将荧光定量RT-PCR技术用于埃博拉病毒的定量检测中,并且建立了EBOV SYBRGreenⅠ荧光定量RT-PCR检测方法。     

双重荧光RPA扩增方法快速鉴别两种血清型水泡性口炎病毒

本研究利用重组酶聚合酶扩增(RPA)技术,根据水泡性口炎病毒印第安纳型(VSV-IND)和新泽西型(VSVNJ)相对保守的L基因为靶序列设计并筛选出两套特异性的引物和探针,建立了快速鉴别检测水泡性口炎病毒两种血清型的双重荧光RT-RPA方法。试验结果表明,该方法特异性强,与猪水泡病病毒(SVDV)、口蹄疫病毒(FMDV)、蓝舌病病毒(BTV)、猪繁殖与呼吸综合征病毒(PRRSV)、牛病毒性腹泻病毒(BVDV)、猪瘟病毒(CSFV)等灭活抗原核酸无交叉反应;灵敏度高,最低可检测核酸浓度为12.7fg/μL;简便快速,反应时间短(15min),且重复性好。利用所建立方法对124份临床样品进行检测,结果与双重荧光RT-PCR一致。本文为VSV-IND和VSV-NJ的快速鉴别检测提供一种新方法,尤其适合现场检疫或基层实验室的快速检测。     

蜜蜂克什米尔病毒实时荧光RT-PCR检测方法的建立和评价

蜜蜂克什米尔病毒(Kashmir bee virus,KBV)是一种高毒力的急性蜜蜂病毒,可以引起蜜蜂的死亡和蜂群崩溃.本研究旨在建立一种灵敏、快速检测KBV的TaqMan实时荧光RT-PCR检测方法.参照GenBank中polymerase polyprotein有关基因序列,设计一组特异性引物和探针,并通过体外转录法制备RNA标准品作为阳性模板.在对反应体系进行优化的基础上,建立了 KBV的实时荧光RT-PCR检测方法并进行了特异性试验、敏感性试验、重复性试验和临床样本验证.结果显示:该方法能有效扩增8×100拷贝/μL～8×107拷贝/μL 的KBV标准品,建立的标准曲线呈现良好的线性关系.该方法的检测灵敏度为8拷贝/μL,对其他蜜蜂病毒不发生交叉反应,具有很好的特异性;重复性试验结果显示组内和组间的变异系数分别低于1％和2％,重复性良好.应用本研究建立方法与常规RT-PCR方法对样品进行检测,TaqMan实时荧光RT-PCR检测方法的特异性优于常规RT-PCR.本研究建立的实时荧光RT-PCR检测具有良好的敏感性、特异性和重复性,为KBV的检测和流行病学调查提供技术支持.     

Hendra病毒一步法Real-time RT-PCR检测方法的建立

目的 建立针对Hendra病毒N基因的一步法Real-time RT-PCR检测方法,用于Hendra病毒感染样本的快速检测和准确定量.方法 针对Hendra病毒的保守基因N设计引物和探针,构建体外转录的RNA片段作为标准品,建立一步法Real-time RT-PCR反应方法并分析敏感性和特异性.结果 所设计的引物经Blast检索可以用于检测所有已知的Hendra病毒株.本研究建立的一步法Real-time RT-PCR方法可以特异性检测出Hendra病毒,不与Nipah病毒产生交叉反应.检测灵敏度为2.6×100～2.6×101copies/μl.标准曲线的线性范围为2.6×101～2.6×107copies/μl.结论 本研究建立的一步法Real-time RT-PCR方法敏感性和特异性较高,且不易出现污染引起的假阳性结果,适合用于Hendra病毒感染样本的检测.     

A组轮状病毒可视化RT-LAMP方法的建立

【目的】建立一种利用颜色判定的快速、简单、灵敏度高的检测方法,即可视化的逆转录环介导等温扩增(RT-LAMP)方法,并应用于人A组轮状病毒的基因检测。【方法】针对A组轮状病毒VP6基因的6个保守区域设计4条特异性引物,在64 °C恒温条件下进行核酸扩增反应1 h,在扩增前加入染料钙黄绿素(Calcein)作为反应指示剂,以钙黄绿素的颜色变化作为结果判定标准。评价该方法的特异性和灵敏度,并同时利用RT-LAMP和RT-PCR两种方法对90份临床腹泻样本中的病毒核酸进行检测。【结果】RT-LAMP方法特异性较高,灵敏度可以达到103 copies/μL RNA分子水平,比RT-PCR高出100倍。对临床标本的检出率与RT-PCR方法相当。【结论】建立的RT-LAMP法灵敏度较高,特异性强,节省时间,结果可视化,具有野外检测和现场快速检测的潜力。     

琉球病毒、索尔韦齐病毒、苏里斯病毒等三种沙粒病毒实时荧光RT-PCR检测方法研究

建立可检测琉球病毒(Ryukyu virus,RYKV),索尔韦齐病毒(Solwezi virus,SOLV)以及苏里斯病毒(Souris virus,SOUV)等三种沙粒病毒的实时荧光定量RT-PCR检测方法.分析三种病毒流行病学分布特征,从国际公共数据库搜索下载基因组序列,进行比对分析,确定检测靶标,借助primer premier 6.0生物信息学软件,设计引物和探针,建立实时荧光定量RT-PCR检测方法,利用化学合成和体外转录方法制备模拟样本,比较评价三种方法的检测限、特异性、重复性特征.所建实时荧光定量RT-PCR检测方法均可有效扩增检测病毒RNA靶标,检测限分别为40拷贝/μL、7拷贝/μL和15拷贝/μL,检测汉城病毒、汉滩病毒、登革病毒Ⅰ～Ⅳ型分离株、发热伴血小板减少综合病毒及30份健康人血清样本无非特异性扩增,三种病毒相互间以及其他8种出血热相关沙粒病毒RNA间无交叉反应,重复性比较分析显示变异系数均在2％以内.本研究建立的检测RYKV、SOLV和SOUV三种沙粒病毒的实时荧光RT-PCR方法具备用于相关疑似感染者临床样本、宿主动物标本以及进出口物品的筛查检测的潜力,但因未经基于实际病毒感染样本的比较评价,检测结果的解释仍具有一定的局限性.     

轮状病毒NASBA检测研究

轮状病毒是世界范围内流行性胃肠炎暴发的重要病因。以患者粪便为样抽提轮状病毒RNA,在轮状病毒VP7高保守基因区段上设计引物,运用核酸序列依赖的扩增(NASBA)法进行检测,变性琼脂糖凝胶电泳和Northern杂交验证。NASBA预期的特异性产物为392bp,并在仅以目标核酸为模板或在浓度高达1μg/μL的非特异性核酸存在的混合模板中,均有清晰的目标带产生,表现出了很高的特异性。其灵敏度和RT-PCR相同甚至更高,可检测到50pg的核酸,并且当反应时间为3h时检测灵敏度最高。NASBA法扩增效率高、灵敏度高、快速易操作,尤其适用在基层单位推广应用。     

实时定量RT-PCR检测鱼类传染性造血器官坏死病毒方法的建立与应用

建立了Taqman 实时定量RT-PCR方法检测传染性造血器官坏死病毒(IHNV).选取IHNV病毒的N蛋白基因保守序列,利用Primer Express 2.0软件设计引物和探针.以梯度稀释的含有IHNV目的扩增片段的质粒作为标准品,进行定量RT-PCR反应以确定检测灵敏度.病毒浓度在5×106 -5个拷贝,共7个数量级的范围内,定量RT-PCR反应有"S"型扩增曲线,检测灵敏度为5个拷贝.根据病毒拷贝数与定量反应Ct值的关系,绘制了标准曲线.该方法具有特异性,对鲤春血症病毒(SVCV)、病毒性出血性败血症(VHSV)、传染性胰脏坏死病毒(IPNV)、草鱼呼肠孤病毒(GCRV)、流行性造血器官坏死病毒(EHNV)、EPC细胞系、牙鲆的核酸都没有扩增反应.在50批待检样品中,有3批鱼类感染IHNV,利用标准曲线进行了定量分析.实时定量RT-PCR检测IHNV方法,灵敏度高,特异性好,可以进行定量分析,在鱼病的快速检测上具有重要意义.     

African Cassava Mosaic Virus (ACMV): Stability of Purified Virus and Improved Conditions for its Detection in Cassava Leaves by ELISA

African Cassava Mosaic Virus (ACMV) was purified by a method which allowed the separation of monomer from dimcr virus particles. Optimal conditions for storing purified virus to be used for immunization were determined by ELISA and inoculation on Nicotiana benthamiana. Purified virus could be stored without loss of infectivity and serological activity for more than 145 days at 4 °C or frozen at –20 °C, but not longer than 40 days in the presence of 50 % redistilled glycerol. Rabbit and chicken immunoglobulins were used to detect ACMV in cassava leaves by direct and indirect ELISA. To obtain the same absorbance values, it was necessary to use longer incubation times with the indirect method, but the virus detection end-point m sap from infected plants was the same for the two methods (1/512). Conditions for improving virus detection tn cassava samples were determined. The virus was better detected when leaves from diseased plants were ground in 100 mM Tris-HCl containing 1 % polyvinylpyrrolidone at pH 8.5 than in phosphate buffer. Plant inhibitors were the restricting factor in the detection of virus by ELISA, but this difficulty was avoided when leaves to be tested were harvested from the top of the cassava plants.     

中华鳖病毒的血清学检测

中华鳖病毒（ＴＳＶ）是从病鳖中分离到的一种病毒病原。经细胞培养和差异离心制备ＴＳＶ抗原,肌注家兔获ＴＳＶ抗体（ＴＳＶ－Ａｂ）,中和效价为１：２０,用ＴＳＶ－Ａｂ进行双向免疫扩散和间接ＥＬＩＳＡ检测,被检样品有健康和病鳖组织匀浆液、ＴＳＶ细胞培养液、提纯的ＴＳＶ,以及鱼传染性胰脏坏死病毒（ＩＰＮＶ）、草鱼呼肠孤病毒（ＧＣＶ）、鱼病毒性出血败血症病毒（ＶＨＳＶ）、鲁痘疮病毒（Ｃａｒｐ ｐｏｘ ｖｉｒｕ     

Time-resolved fluoroimmunoassay of potato virus M with monoclonal antibodies

Mouse monoclonal antibodies (MAbs) specific for potato virus M (PVM) were prepared and the properties of three of them were studied. MAb M4C1 is IgG2b, it binds with high affinity to PVM coat protein, to purified virus preparations and recognises PVM in infected potato leaves and tubers. MAb M6D5 is IgG2a and also reacts with PVM coat protein, purified PVM and with PVM in potato leaf and tuber extracts. In double-antibody sandwich ELISA (DAS ELISA) MAbs M4C1 and M6D5 reacted with all 17 PVM isolates tested. MAb M7 is IgG2b and recognises PVM only in indirect dot ELISA on nitrocellulose filters and viral coat protein on Western blots. MAbs against PVM were used as capture antibodies and europium-labelled MAbs as conjugates in time-resolved fluoroimmunoassay (EuTRFIA). The standard EuTRFIA curve of PVM detection is approximately linear over a range of PVM concentrations from 0.5 ng/ml to 1000 ng/ml. The lowest PVM concentration detectable in EuTRFIA was 0.5 ng/ml and correspondingly 6 ng/ml in DAS ELISA. The use of the europium chelate label allows PVM detection in potato leaf and tuber sap at dilutions greater than 10^--⁴ with very low background fluorescence. EuTRFIA with MAbs, with either one or two incubations is about 10–20 times more sensitive for PVM detection than is DAS ELISA. PVM and PVX, mixed with healthy potato tuber sap, were simultaneously tested in a single sample at concentrations lower than 10 ng/ml by double-label TRFIA using europium-labelled MAbs to PVM and samarium-labelled MAbs to PVX.     

应用斑点免疫结合法检测植物病毒

用改进的斑点免疫结合法,检测了烟草花叶病毒、黄瓜花叶病毒、豇豆花叶病毒、芋花叶病毒、柑桔速衰病毒和柑桔顽固病螺原体。无论用单克隆抗体还是多克隆抗体,全血清还是提纯的IgG,均获得满意的结果。直接法与间接法结果相同。在测定豇豆花叶病毒和芋花叶病毒时,与酶联免疫吸附试验和免疫电镜进行比较。表明无论是对纯化病毒还是感病植物汁液,其测定的敏感性均优于后二法,豇豆花叶病毒的可测感度是0.35ng,芋花叶病毒为0.83ng。以含0.5％吐温20的Tris缓冲液封闭硝基纤维素薄膜固相载体的未结合部位,其效果与牛血清白蛋白相同。应用碱性磷酸酶标记抗体以及羟基吲哚磷酸盐和氮蓝四唑为底物较合适,这种底物可在室温下长期保存,且反应产物为不褪色的紫色。易于观察和保存。     

Use of the Reverse Transcription-Polymerase Chain Reaction for the Detection of Pelargonium Flower Break Carmovirus

A polymerase chain reaction (PCR)-based assay was used to detect pelargonium flower break carmovirus (PFBV) in total RNA extractions made from infected Pelargonium plants. Extracts were reverse transcribed (RT) and the resultant cDNA was amplified by PCR, using oligonucleotide primers specific for 343, 510 and 832 base pair fragments of the RNA-dependent RNA polymerase gene of PFBV.
The specificity and sensitivity of RT-PCR were compared with the enzyme-linked immunosorbent assay (ELISA) for the detection of PFBV in Pelargonium tissues. The virus could be detected efficiently in high dilutions of sap from infected plants and at low concentrations of purified virus. Although ELISA is a powerful tool for virus detection, RT-PCR was over 1000 times more sensitive in detecting PFBV in leaf extracts of infected Pelargonium than was ELISA. The limit of detecting PFBV RNA by RT-PCR was 200 fg, compared with 200 pg of virus by ELISA.     

Comparison of Polyclonal Antisera in the Detection of Tomato Spotted Wilt Virus Using the Double Antibody Sandwich and Cocktail ELISA

Different polyclonal antisera and enzyme-linked immunosorbent assay (ELISA) procedures have been tested for their potential to detect tomato spotted wilt virus (TSWV). The virus could efficiently be detected in high dilutions of sap from infected plants, and at low concentrations of purified virus and nucleocapsid protein preparations in the cocktail ELISA and the double antibody sandwich ELISA (DAS-ELISA). Amounts of 1 to 3 ng of virus protein still gave positive readings using purified preparations, while sap could be diluted approximately 100,000 times. Differences in the detection level were observed using nucleocapsid protein antiserum (anti-N-serum) and the antiserum against intact virus particles (anti-TSWV-serum), but both antisera showed to be powerful sera for the detection of TSWV. Using anti-N-serum, TSWV could be detected in highly diluted extracts of different hosts, and also in leaf extracts or intact tissues stored for 30 days under different conditions. These results indicate that the TSWV nucleocapsid protein remains antigenic for long periods.     

The detection by serological methods of viruses infecting the rose

Homogenates of herbaceous test plants infected with arabis mosaic virus (AMV), prunus necrotic ringspot virus (PNRSV), or strawberry latent ringspot virus (SLRV), and purified virus preparations were used to assess the sensitivities of four serological methods (the enzyme-linked immunosorbent assay - ELISA, immunodiffusion in gels, the latex flocculation assay, and serologically specific electron microscopy -SSEM) for the detection of these viruses. The latex test was up to 250 times more sensitive than gel immunodiffusion, but SSEM and ELISA were respectively up to 1000 and 200 times more sensitive than the latex test. Gel immunodiffusion and latex tests failed to detect any of the viruses in infected roses. Although ELISA reliably detected PNRSV and SLRV when leaves from infected roses were homogenised in a leaf: buffer ratio of 1 g:10 ml, AMV was occasionally undetected. However, when a modified ELISA technique, which reduced non-specific reactions, was used some PNRSV-infected roses were also not detected. Detection by SSEM was c. twice as sensitive as ELISA for all three viruses in rose extracts. The relative advantages of ELISA and SSEM for the detection of plant viruses are discussed.     

An enzyme-linked immunosorbent assay for the detection of cytoplasmic polyhedrosis virus

An enzyme-linked immunosorbent assay (ELISA) for the detection of Euxoa scandens cytoplasmic polyhedrosis virus (EsCPV) is described. Antisera to EsCPV, produced in rabbits and guinea pigs, are specific to EsCPVs when used in an indirect assay. This indirect assay approach permits the detection of homologous antigens at a concentration of about 1 μg/ml; however, this procedure is not suitable to test large numbers of unpurified specimens. For this type of analysis we used a double antibody sandwich assay which can detect 10 ng/ml of homologous antigen in unpurified material without nonspecific reactions. This assay is used to diagnose EsCPV infections in field and laboratory studies.     

Transient and stable expression of hepatitis B surface antigen in tomato (Lycopersicon esculentum L.)

Cotyledonary leaves of tomato cv. Megha were transformed with the hepatitis B virus ‘s’ gene, which encodes surface antigen. Six plant expression cassettes (pHBS, pHER, pEFEHBS, pEFEHER, pSHER and pEFESHER) were used to assay the possible expression levels by agroinfiltration. The maximum transient expression level of 489.5 ng/g D.W. was noted in pEFEHER-infiltrated cotyledonary leaves. Transgenic tomato plants with pEFEHBS and pEFEHER expression cassettes were regenerated and characterized by molecular analysis. The expression of the antigen in the fruits was confirmed by RT-PCR and ELISA analysis. This is the first report on the expression of hepatitis B surface antigen in tomato.     

Serological studies on cassava latent virus

Particles of cassava latent virus (CLV) were purified by a method that yielded up to 3 mg per 100 g of systemically infected Nicotiana benthamiana leaf. Specific antiserum was prepared and used for enzyme-linked immunosorbent assay (ELISA), which detected purified virus at 5 ng/ml. As estimated by ELISA, CLV antigen reached a greater concentration in leaves of N. benthamiana plants kept at 20–25 °C than in those at 15 °C or 30 °C. CLV was also detected in leaf extracts of naturally infected cassava plants kept at 25 C but its concentration was only 1–7% of that in comparable extracts from N. benthamiana. Staining sections of N. benthamiana leaves with fluorescent antibody indicated that CLV particle antigen accumulates in the nuclei of many phloem cells and of some cells in other tissues. In tests on mosaic-affected cassava plants of Angolan origin, three plants were found in which CLV could not be detected by either ELISA or immunosorbent electron microscopy, or by transmission to indicator plants. This suggests that the mosaic symptoms were caused by a pathogen other than CLV, but no such agent was detected by electron microscopy of leaf extracts. Three kinds of serological test indicated that CLV is related to bean golden mosaic virus. Evidence was also obtained of a distant relationship to beet curly top virus but none was detected to four other geminiviruses.