Phytopathology. 1999 Apr;89(4):336-42. doi: 10.1094/PHYTO.1999.89.4.336.
ABSTRACT Comparison of a sampling of complementary DNA (cDNA) sequences from the Florida citrus tristeza virus (CTV) isolates T3 and T30 to the sequence of the genome of the Israeli isolate VT showed a relatively consistent or symmetrical distribution of nucleotide sequence identity in both the 5' and 3' regions of the 19.2-kb genome. In contrast, comparison of these sequences to the sequence of isolate T36 showed a dramatic decrease in sequence identity in the 5' proximal 11 kb of the genome. A cDNA probe derived from this region of the T36 genome hybridized to double-stranded RNA (dsRNA) of only 3 of 10 different Florida CTV isolates. In contrast, analogous probes from T3 and T30 hybridized differentially to the seven isolates not selected by the T36 probe. Primers designed from cDNA sequence for polymerase chain reaction (PCR) selectively amplified these 10 isolates, allowing them to be classified as similar to T3, T30, or T36. In contrast, individual cDNA probes derived from the 3' terminal open reading frames of the T3, T30, and T36 genomes all hybridized to dsRNA from all Florida CTV isolates tested, and PCR primers designed from the T36 capsid protein gene sequence amplified successfully from all isolates. Based on these data, we propose the creation of two groups of CTV, exemplified by the VT and T36 isolates, respectively. Isolates in the VT group, which include isolates VT, T3, and T30, have genomic sequence divergence that is relatively constant in proportion and distribution throughout the genome, and candidate isolates for that group could be considered strains of the same virus. The T36 group is differentiated from the VT group by the highly divergent 5' genomic sequence. This 5' region of the CTV genome, thus, can serve as a measure of the extent of sequence divergence and can be used to define new groups and group members in the CTV complex.
摘要 对佛罗里达甜橙萎缩病毒（CTV）分离株 T3 和 T30 的 cDNA 序列进行抽样比较，将其与以色列分离株 VT 的基因组序列进行比较，结果显示在 19.2kb 基因组的 5'和 3'区域中核苷酸序列同一性相对一致或对称。相比之下，将这些序列与分离株 T36 的序列进行比较，结果显示在基因组的 5'近端 11kb 区域中序列同一性显著降低。源自 T36 基因组该区域的 cDNA 探针仅与 10 个不同佛罗里达 CTV 分离株中的 3 个杂交。相比之下，T3 和 T30 的类似探针则与未被 T36 探针选择的 7 个分离株不同地杂交。根据 cDNA 序列设计的用于聚合酶链反应（PCR）的引物选择性地扩增了这 10 个分离株，从而将它们归类为类似于 T3、T30 或 T36。相比之下，源自 T3、T30 和 T36 基因组 3'末端开放阅读框的单个 cDNA 探针均与所有测试的佛罗里达 CTV 分离株的 dsRNA 杂交，并且根据 T36 衣壳蛋白基因序列设计的 PCR 引物均成功地从所有分离株中扩增。基于这些数据，我们提出创建两个 CTV 组，分别由 VT 和 T36 分离株代表。VT 组中的分离株，包括 VT、T3 和 T30，其基因组序列的差异在整个基因组中比例和分布相对恒定，并且该组的候选分离株可以被认为是同一病毒的株系。T36 组与 VT 组的区别在于高度差异的 5'基因组序列。因此，CTV 基因组的这个 5'区域可以作为序列差异程度的衡量标准，并可用于定义 CTV 复合体中的新组和组成员。
