Two Circular Single-stranded DNAs Associated with Banana Bunchy Top Virus

Nucleic acids extracted from partially purified banana bunchy top virus (BBTV) consisted of 20 Kb DNA, 0.9–1.1 Kb DNA and 0.3 Kb RNA. Partially purified BBTV preparations predigested with DNase and RNase before particle disruption and nucleic acid isolation yielded only the 0.9–1.1 Kb DNA, but no corresponding nucleic acid band was obtained in total nucleic acid isolated from healthy banana tissue. Analysis of two BBTV cDNA clones showed that clone 1 consisted of 287 nucleotides and clone 2 contained a 1.0 Kb DNA insert. Clone 1 is not part of clone 2. When two pairs of primers, each pair in opposite orientation were used to amplify BBTV DNA by PCR using the total DNA from diseased banana tissues or DNA encapsidated in BBTV particle as the template, a DNA product of 1.1 Kb was generated by both, results indicating that the BBTV DNAs are circular. Additional results suggested that BBTV contained at least two circular ssDNAs designated BBTV cssDNA I (containing clone 1 nucleotide sequence) and BBTV cssDNA II (containing clone 2 nucleotide sequence).     

Purification and Characterization of Banana Bunchy Top Virus

Abstract Banana bunchy top virus (BBTV) was successfully purified by a procedure which included pulverizing diseased tissues frozen in liquid nitrogen, clarification of the extract with chloroformbutanol, concentration of the virus by cycles of differential centrifugation, stirring and incubating at 4°C followed by a second cycle of differential centrifugation and sucrose density gradient centrifugation. The concentrations of BBTV obtained from leaf blades and midribs plus petioles were up to 0.34 and 0.56mg/kg tissue, respectively. The virus concentration was highest in diseased leaves collected from October to December, and lowest in those collected from June to September. BBTV is a luteovirus (particles 20– 22 nm in diameter), preparations of which have maximum absorbance at 257 nm, minimum absorbance at 240 nm and a A260/280 ratio of 1.46. The relative molecular mass (M_r) of BBTV coat protein subunit is 21,000, and that of its ssRNA is 2.0 × 10⁶.     

香蕉束顶病毒研究进展

香蕉束顶病毒(Bananabunchytopvirus,BBTV)是引起香蕉束顶病害(Bananabunchytopdisease,BBTD)的病毒,它严重地危害了香蕉的生产。综述了近年来香蕉束顶病毒的分离提纯方法,株系划分以及分类地位,较为全面的介绍了BBTV病毒基因组分结构和各组分编码蛋白的功能等,并提出了目前需要进一步澄清的问题。     

香蕉束顶病毒基因Ⅰ的克隆及序列分析

以中国漳州地区感染ＢＢＴＶ的香蕉组织总ＤＮＡ为模板,根据我国台湾地区ＢＢＴＶ分离物基因组Ⅰ序列,设计并合成了一对引物,通过ＰＣＲ扩增出约５００ｂｐ的片段。利用ｐＢｌｕｅｓｃｒｉｐｔⅡＳＫ Ｔ－载体获得此片段的克隆,经测序表明为ＢＢＴＶ组分Ⅰ的部分序列。由已测知的ＢＢＴＶ基因组Ⅰ序列设计一对相邻引物,以我国漳州的感染ＢＢＴＶ香蕉组织总ＤＮＡ为模板,通过ＰＣＲ坟增出约１．１ｋｂ的片段。利用ｐＢｌｕｅｓ     

香蕉束顶病毒DNA组分6的克隆和序列分析

香蕉束顶病(banana bunchy top disease,BBTD)是香蕉生产上重要的病害之一,它威胁着世界约1/4香蕉产区的生产[1].到1998年7月,世界上报道发生该病害的国家和地区达20多个,遍及亚洲、南太平洋地区和少数非洲国家.     

Rickettsial Relative Associated with Papaya Bunchy Top Disease

The phylogeny of a previously unidentified, obligate laticifer-inhabiting bacterium associated with the papaya bunchy top disease was investigated. Portions of genes corresponding to those for 16S rRNA, the flavoprotein subunit of succinate dehydrogenase (SdhA), citrate synthase (GltA), and the 17-kDa rickettsial common antigen were isolated and sequenced from the non-cultivable bacterium from diseased plants. Comparative sequence analyses consistently indicated that the bacterium is a member of the α-subdivision of the Proteobacteria and of the genus Rickettsia. The rickettsia was detected by polymerase chain reaction in diseased, but not healthy, papaya tissues and in the leafhopper vector, Empoasca papayae, providing further evidence of the possible etiological role of the bacterium in the disease. Although Rickettsia have been found naturally in arthropods and can be pathogenic to humans and other vertebrates, this is the first evidence of its kind implicating a Rickettsia as a plant pathogen. Received: 21 July 1997 / Accepted: 28 July 1997     

香蕉束顶病毒NS株DNA组分5的克隆和序列分析

本文利用PCR技术扩增得到香蕉束顶病毒(BBTV)NS株DNA组分5的全基因,该基因全长为1014nt,具有一个开放阅读框,编码146个氨基酸,蛋白质二级结构包括6个α螺旋,7个β折叠。NS株系与南太平洋组澳大利亚、夏威夷、埃及分离物DNA组分5核苷酸和编码的氨基酸序列相比较,核苷酸序列同源率介于88%～89%之间,氨基酸序列同源率介于80%～88%之间。NS株系与其它分离物在编码成视网膜细胞瘤蛋白(Retinoblastomaprotein,Rb)的基元序列“LXCDE”附近的二级结构上表现明显的差异,推测这种差异可能影响与植物中Rb蛋白的结合效率。     

香蕉束顶病毒海口分离物核穿梭蛋白(NSP)的纯化及抗血清制备

本研究以本实验室保存的含重组载体pDEST17-NSP的原核表达菌株E.coli BL21(DE3)为材料,于25℃、0.1 mmol/L IPTG条件下诱导4 h,集菌后超声波破碎,获得以包涵体形式表达的约20 kD的融合蛋白.实验结果表明,将沉淀的融合蛋白溶于含6 mol/L尿素的Binding Buffer中,再经Ni2+-NTA亲和层析纯化后,可获得高纯度的融合蛋白.将纯化融合蛋白经12%SDS-PAGE电泳,切胶回收目的带,液氮研磨并按1:1(W/V)混合佐剂,4次免疫家兔,获得BBTV病毒核穿梭蛋白的特异性抗血清.以融合蛋白作抗原,间接ELISA法测定其抗血清效价为1:5 000.田间检测样品的最佳抗血清工作浓度为1:500.Western Blot鉴定结果表明抗血清能与目的蛋白特异性结合.本研究的结果将为下一步NSP基因转录调控和蛋白功能研究奠定一定基础.     

香蕉束顶病毒NS株DNA组分5的克隆和序列分析

本文利用PCR技术扩增得到香蕉束顶病毒(BBTV)NS株DNA组分5的全基因,该基因全长为1014nt,具有一个开放阅读框,编码146个氨基酸,蛋白质二级结构包括6个α-螺旋,7个β-折叠.NS株系与南太平洋组澳大利亚、夏威夷、埃及分离物DNA组分5核苷酸和编码的氨基酸序列相比较,核苷酸序列同源率介于88%～89%之间,氨基酸序列同源率介于80%～88%之间.NS株系与其它分离物在编码成视网膜细胞瘤蛋白(Retinoblastoma protein,Rb)的基元序列"LXCDE"附近的二级结构上表现明显的差异,推测这种差异可能影响与植物中Rb蛋白的结合效率.     

香蕉束顶病毒复制酶基因克隆及转基因表达

以广州市郊获得的香蕉束项病毒(BBTV)的DNA为模板,进行PCR扩增得到香蕉束项病毒复制酶基因的1.1 kb DNA.所获得的DNA序列与澳大利亚的BBTV序列的同源性达90%,这部分序列编码香蕉束顶病毒复制酶基因的羧基端.将改造的BBTV复制酶基因克隆到pBll21的CaMV 35S和NOS终止序列之间,构建表达载体,并采用基因枪轰击香蕉试管苗生长点组织的方法,经PCR检测和Westem blot分析,获得4株具有BBTV复制酶基因整合表达的To代转基因香蕉.转基因植株的抗病性正在检测之中.     

Production of Monoclonal Antibodies Against Banana Bunchy Top Virus and Their Use in Enzyme-Linked Immunosorbent Assay

Zusammenfassung Produktion monoklonaler Antikorper gegen das Banana Bunchy Top Virus und ihre Anwendung in einem Enzym-gekoppelten Immunosorbentassay
Nach einer Immunisierung von Balb/s-Mausen mit gereinigtem Banana Bunchy Top Virus (BBTV) wurde in allen 480 Vertiefungen aus einer Fusion Hybridomas gefunden. Aucerdem wurde in 92% der Kulturflussigkeiten dieser Vertiefungen eine positive Reaktion gegen das BBTV durch Plate Trapped Antigen (PTA) ELISA (auch als indirekter ELISA bekannt) festgestellt. Nach einer dritten Uberprufung behielten 84 Hybridomazellinien ibre Fahigkeit, BBTV-spezifische Antikorper zu produzieren. Durch das Klonen dieser Hybridomas bei limitierender Verdunnung zu einzelnen Zellen wurden 58 monoklonale Zellinien erhalten, die in der Lage waren, BBTV-spezifische Antikorper zu produzieren. Die von diesen monoklonalen Hybridomas produzierten Antikorper waren hauptsachlich vom Isotyp lgG2a. Die Antikorpertiter im Kulturzelluberstand und in der ascitischen Flussigken betrugen bei einem Klon 10⁴ bzw, 10⁴, und bei einem anderen Klon sogar 10⁴ bzw. 10⁴. Hybridomas produzierten 40- bis 62fach mehr anti-BBTV spezifische Antikorper in Mausasciten als in Kultur. Die minimale. aktive Konzentration gereinigtes Immunoglobulin, von drei Hybridomas produziert, lag im Bereich von 0.03 bis 0.06 μg/ml dagegen wurde eine minimale durch PTA ELISA ertacbare Konzentration von BBTV-Antigen von 0.26 μg/ml ermittelt. Antibody Trapped Antigen (ATA) ELISA (auch als direkter ELISA bekannti war bei der Ermittlung von BBTV 16fach empfindlicher als PTA ELISA. Obwobl PTA ELISA das BBTV im Rohextrakt des erkrankten Gewebes nicht ertassen konnte, war es mit ATA ELISA moglich das Vorhandensein des Virus auch in 1: 512 verdunntem Extrakt zu errnitteln.     

利用超低温保存方法脱除香蕉束顶病毒的研究

香蕉束顶病毒(BBTV)是香蕉生产中的严重病害之一,主要通过感病材料和香蕉交脉蚜等昆虫进行传播,目前尚无有效防治方法.本研究以感染BBTV的巴西蕉(Musa AAA Cavendish)为材料,研究了感染BBTV的巴西蕉离体再生和超低温保存技术条件,表明离体茎尖在MS+6-BA 4 0 mg/L+NAA 0 4 mg/L的培养基上分化不定芽较好;采用玻璃化法超低温保存技术保存带有BBTV的香蕉茎尖,再生后植株BBTV脱除率达到60 6%,而常规的茎尖培养对BBTV的脱除率仅为26 7%.     

香蕉束顶病毒中国漳州分离物DNA 4的克隆及非编码区的启动子活性初探

应用PCR方法克隆了香蕉束顶病毒中国漳州分离物(Banana bunchy top virus Chinese Zhangzhou isolate, BBTV-ZZ) DNA 4.序列分析表明其序列全长为1 039 nt,归属于亚洲组.5′ RACE分析确定其转录起始位点是269 nt处的A.利用PCR方法亚克隆了BBTV-ZZ DNA 4非编码区序列并将其插入到植物表达载体pCAMBIA 1304中的 gfp∶∶gus 基因上游得到重组质粒pTA2.将含pTA2和pCAMBIA 1304的根癌土壤杆菌(Agrobacterium tumefaciens)注射进烟草(Nicotiana tabacum L. cv. Xanthi NC)叶片,3～5 d后剪下注射部位的叶片进行GUS和GFP的表达分析.pTA2(含BBTV-ZZ DNA 4非编码区)、pCAMBIA 1304(含CaMV 35S启动子)和未注射的烟草叶片的GUS活性分别为1.007 0 pmol MU*μg-1*min-1 , 2.069 0 pmol MU*μg-1*min-1和0.021 4 pmol MU*μg-1*min-1.注射含pTA2和pCAMBIA 1304植物表达载体根癌土壤杆菌以及未注射的烟草叶片的每毫克总蛋白的GFP间接ELISA在490 nm的吸光值分别为89.577、100.440和3.287.     

香蕉束顶病毒中国漳州分离物DNA4的克隆及非编码区的启动子活性初探

应用PCR方法克隆了香蕉束顶病毒中国漳州分离物 (BananabunchytopvirusChineseZhangzhouisolate ,BBTV_ZZ)DNA 4。序列分析表明其序列全长为 10 39nt,归属于亚洲组。 5′RACE分析确定其转录起始位点是 2 6 9nt处的A。利用PCR方法亚克隆了BBTV_ZZDNA 4非编码区序列并将其插入到植物表达载体pCAMBIA 130 4中的gfp∶∶gus基因上游得到重组质粒pTA2。将含pTA2和pCAMBIA 130 4的根癌土壤杆菌 (Agrobacteriumtumefaciens)注射进烟草 (NicotianatabacumL .cv .XanthiNC)叶片 ,3～ 5d后剪下注射部位的叶片进行GUS和GFP的表达分析。pTA2 (含BBTV_ZZDNA 4非编码区 )、pCAMBIA 130 4 (含CaMV 35S启动子 )和未注射的烟草叶片的GUS活性分别为 1 0 0 70pmolMU·μg-1·min-1,2 .0 6 90pmolMU·μg-1·min-1和 0 .0 2 14pmolMU·μg-1·min-1。注射含pTA2和pCAMBIA 130 4植物表达载体根癌土壤杆菌以及未注射的烟草叶片的每毫克总蛋白的GFP间接ELISA在 4 90nm的吸光值分别为89 5 77、10 0 4 4 0和 3 2 87。     

Transmission of the Phytoplasma Associated with Bunchy Top Symptom of Papaya by Empoasca papayae Oman

Transmission tests were conducted with field‐collected Bunchy Top Symptoms (BTS) phytoplasma‐infected specimens of Empoasca papayae. BTS developed in all eight inoculated papayas 3 months later. The BTS phytoplasma was identified in six of eight inoculated papayas, whose partial 16S rRNA sequence (GenBank Accession no. FJ6492000 ) was 99.9% identical with those from the collected papayas (GenBank Accession no FJ649198 ) and E. papayae (GenBank Accession no. FJ649199 ), all of which are members of group 16SrII, ‘Candidatus Phytoplasma aurantifolia’. Results confirmed the ability of E. papayae to transmit the BTS phytoplasma.