Yeh H H, Su H J, Chao Y C
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.
Virology. 1994 Feb;198(2):645-52. doi: 10.1006/viro.1994.1076.
The single-stranded (ss) and double-stranded (ds) viral-associated DNAs (VADs) of banana bunchy top virus (BBTV) were characterized. The ssVADs were shown to be the viral genomic DNA and the dsVADs are the likely replication forms. Both dsVADs and ssVADs contain DNA species that cross-hybridize to each other. Under the electron microscope, both circular and linear DNAs were observed from these VAD species. Libraries were constructed from VADs to further characterize them. Two overlapping VAD clones were isolated and their combined sequence indicated that their corresponding VAD, named as BBTV component 2, is circular with a size of 1095 nt. The largest ORF spans from nucleotides 82 to 390, which is sandwiched by a putative TATA box, 54 nt upstream from the first ATG codon, and a AATAAA motif, 7 nt downstream from the UAA codon. Although the sequence of this VAD is different from the previously reported BBTV component 1 (Harding et al., J. Gen. Virol. 74, 323-328, 1993) and the genome of coconut foliar decay virus (Rohde et al., Virology 176, 648-651, 1990), stretches of highly homologous sequences were found between BBTV component 2 and the other two viral genomes by computer analysis. The sequence of BBTV component 1 is highly homologous to one of the clones, pBTs26, in the VAD library. Nevertheless, our libraries still contain many clones which hybridized with ss viral genomic DNAs but not with pBTs26 and BBTV component 2, indicating that the viral genome consists of more than two components.
对香蕉束顶病毒（BBTV）的单链（ss）和双链（ds）病毒相关DNA（VAD）进行了表征。单链VAD被证明是病毒基因组DNA，双链VAD可能是复制形式。双链VAD和单链VAD都含有相互交叉杂交的DNA种类。在电子显微镜下，从这些VAD种类中观察到了环状和线性DNA。构建了VAD文库以进一步对其进行表征。分离出两个重叠的VAD克隆，它们的组合序列表明其对应的VAD（命名为BBTV组分2）是环状的，大小为1095 nt。最大的开放阅读框跨度为核苷酸82至390，其两侧分别是一个假定的TATA框（位于第一个ATG密码子上游54 nt处）和一个AATAAA基序（位于UAA密码子下游7 nt处）。尽管该VAD的序列与先前报道的BBTV组分1（Harding等人，《普通病毒学杂志》74，323 - 328，1993年）以及椰子叶腐烂病毒的基因组（Rohde等人，《病毒学》176，648 - 651，1990年）不同，但通过计算机分析发现BBTV组分2与其他两个病毒基因组之间存在高度同源的序列片段。BBTV组分1的序列与VAD文库中的一个克隆pBTs26高度同源。然而，我们的文库中仍包含许多与单链病毒基因组DNA杂交但不与pBTs26和BBTV组分2杂交的克隆，这表明病毒基因组由两个以上的组分组成。
