Genome organization of the Chelonus inanitus polydnavirus:: excision sites, spacers and abundance of proviral and excised segments
Genome organization of the Chelonus inanitus polydnavirus:: excision sites, spacers and abundance of proviral and excised segments
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DOI：
10.1099/vir.0.82396-0
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发表时间：
2007-02-01
影响因子：
3.8
通讯作者：
Lanzrein, Beatrice
中科院分区：
文献类型：
--
作者：
Annaheim, Marc;Lanzrein, Beatrice
多dna病毒仅与卵蜂科和卵蜂科的寄生蜂（卵蜂病毒和卵蜂病毒）存在共生关系。它们有一个由环状双链DNA组成的片段基因组。在原病毒线性形式中，它们被整合到黄蜂的基因组中；在两种臂状病毒中，发现片段是聚集的。前病毒片段有直接的末端重复。片段切除被认为是通过形成环和重组并置这些重复来发生的；一个重复的拷贝在环状片段中结束，另一个在重新连接的DNA中结束。在此，我们分析了螯虾bracovirus （CiV）的四个片段的切除/圆化位点，发现它们与已知的两个位点相似；在综合数据的基础上，发现了一个扩展切除位点基序。对片段侧翼序列的分析首次鉴定出多dna病毒原片段之间的一个完整和几个部分间隔。前病毒段CiV14和CiV22.5之间的间隔段长度为2065 bp；CiV14和CiV22.5的末端重复序列具有相反的方向，由此提出了原病毒簇环的空间组织模型。通过各种方法表明，间隔物不切除或注入到宿主。对原病毒形式和切除形式的各种片段的相对丰度的测量首次表明，丰富的片段存在于原病毒形式的多个拷贝中。
Polydnaviruses are only found in symbiotic association with parasitic wasps within the families Ichneumonidae and Braconidae (ichnoviruses and bracoviruses). They have a segmented genome consisting of circular double-stranded DNA. In the proviral linear form they are integrated in the wasp's genome; in two bracoviruses, segments were found to be clustered. Proviral segments have direct terminal repeats. Segment excision has been proposed to occur through juxtaposition of these repeats by formation of a loop and recombination; one copy of the repeat then ends up in the circular segment and one in the rejoined DNA. Here we analysed the excision/circularization site of four segments of the Chelonus inanitus bracovirus (CiV) and found that they are similar to the two already known sites; on the basis of the combined data an extended excision site motif was found. Analyses of segment flanking sequences led to the first identification of one complete and several partial spacers between proviral segments in a polydnavirus. The spacer between the proviral segments CiV14 and CiV22.5 has a length of 2065 bp; the terminal repeats of CiV14 and CiV22.5 were seen to have an opposite orientation and from this a model on the spacial organization of the loops of the proviral cluster is proposed. Through various approaches it was shown that spacers are not excised or injected into the host. Measurement of relative abundances of various segments in proviral and excised form indicates for the first time that abundant segments are present in multiple copies in the proviral form.