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根据已报道的两种粉虱传双生病毒DNAβ分子的保守序列设计引物,利用PCR技术从烟草曲叶病毒Y5和Y8分离物中扩增到一类环状DNAβ分子,其全长分别为1333和1338nt.序列分析表明,Y5DNAβ可能编码8个可读框（ORFs）,病毒链和互补链各含有4个ORFs;Y8 DNAβ可能编码7个ORFs,病毒链含有4个ORFs,互补链含有3个ORFs.除茎环结构TAATATTAC外,DNAβ与烟草曲叶病毒Y5和Y8基因组DNA-A序列几乎无同源性.Y5和Y8的DNAβ全长核苷酸序列同源性较高,为85％,而与已报道的胜红蓟黄脉病毒（AYVV）DNAβ及棉花曲叶病毒（CLCuV）的两个DNAβ的同源性为51％～65％.免疫捕获PCR及粉虱传毒实验表明,DNAβ分子包裹在双生病毒粒子中,并伴随病毒由烟粉虱传播.
Primers were designed according to the reported conserved sequences of two microsatellites of the whitefly metagenosis DNAβ molecule. A circular DNAβ molecule was amplified from tobacco leaf curl virus Y5 and Y8 isolates by PCR. The full-length DNAβ molecules were 1333 and 1338nt. Sequence analysis showed that Y5DNAβ could encode 8 open reading frames (ORFs), each containing 4 ORFs in the viral and complementary sequences. Y8 DNAβ may encode 7 ORFs, 4 ORFs in the viral chain, 3 ORFs in the complementary strand Except for the TAATATTAC stem-loop structure, DNAβ has almost no homology with the tobacco leaf curl virus Y5 and Y8 genomic DNA-A sequences.The homology of the DNAβ full-length nucleotide sequence of Y5 and Y8 is 85% The homology between the DNAβ and the reported DNAβ of AYVV DNAβ and cotton leaf curl virus (CLCuV) was 51% ~ 65%. The results of immunocapture PCR and whitefly toxicity test showed that DNAβ molecule Wrapped in twin virions and transmitted by the whitefly virus along with the virus.