中国番木瓜曲叶病毒南宁分离物的基因组结构特征

Genomic organization of Papaya leaf curl China virus isolated from Nanning

从广西南宁田间表现曲叶症状的番木瓜植株上分离到病毒分离物G4,经三抗体夹心ELISA(TAS-ELISA)检测,G4与粉虱传双生病毒的抗体呈阳性反应。对G4 DNA-A全序列测定和分析表明,G4 DNA-A全长2 748个核苷酸,共编码6个ORFs。同源性比较及系统进化关系分析表明,G4 DNA-A与在亚洲发现的粉虱传双生病毒关系较近,其中与我国报道的中国番木瓜曲叶病毒(PaLCuCNV)同源性最高,达到98.0%。进一步比较发现,G4 DNA-A编码的AV1、AV2、AC1、AC2、AC3和AC4与PaLCuCNV相应ORFs的氨基酸同源性分别为98.4%、95.7%、97.5%、97.8%、94.1%和94.6%,表明G4应属于PaLCuCNV的一个分离物。G4编码的ORFs与中国胜红蓟黄脉病毒(AYVCNV)、辣椒曲叶病毒(PepLCV)及烟草曲茎病毒(TbCSV)有较高的氨基酸同源性,可能起源于共同的祖先。利用DNA-B及卫星DNAβ的保守引物均未能从G4分离物中扩增出相应的组分。

Virus isolate G4 was collected from papaya plant showing leaf curl symptoms from Nanning, Guangxi province. G4 was able to react specifically with antibodies raised against particles of whitefly-transmired geminiviruses （WTGs） in TAS-ELISA. The complete sequence of G4 DNA-A was determined to be 2 748 nucleotides （nt）. Alignment and phylogenetic analysis show that G4 DNA-A clusters together with WTGs originated from Asian continent and is most closely related to Papaya leaf curl China virus （PaLCuCNV）, with 98.0% nt identity. Comparisons show that G4 DNA-A encoded AV1, AV2, AC1, AC2, AC3 and AC4 share 98.4%, 95.7%, 97.5%, 97.8%, 94.1% and 94.6% amino acid sequence identity ,respectively ,with those of PaLCuCNV, indicating that G4 is an isolate of PaLCuCNV. The individual ORFs encoded by G4 DNA-A share high amino acid sequence identities with those of Ageratum yellow vein China virus （AYVCNV ） , Pepper leaf curl virus （PepLCV） and Tobacco curly shoot virus （TbCSV）, suggesting that the ORFs of these viruses may be derived from the common ancestor. Attempts to amplify the putative DNA-B or satellite DNAβ with conserved primer pairs by PCR have been unsuccessful.