Wang Ze-Hua, Zhou Yue-Nan, Yang Jing, Ye Xi-Qian, Shi Min, Huang Jian-Hua, Chen Xue-Xin
Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.
Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China.
Front Microbiol. 2021 Jan 15;11:608346. doi: 10.3389/fmicb.2020.608346. eCollection 2020.
Polydnaviruses (PDVs), classified into two genera, bracoviruses (BVs) and ichnoviruses (IVs), are large, double-stranded DNA viruses, which are beneficial symbionts of parasitoid wasps. PDVs do not replicate in their infected lepidopteran hosts. BV circles have been demonstrated to be integrated into host genomic DNA after natural parasitization. However, the integrations of IV circles remain largely unknown. Here, we analyzed the integration of ichnovirus (DsIV) in the genomic DNA of parasitized hemocytes. We found that DsIV circles are present in host hemocytes with non-integrated and integrated forms. Moreover, DsIV integrates its DNA circles into the host genome by two distinct strategies, conservatively, and randomly. We also found that four conserved-broken circles share similar motifs containing two reverse complementary repeats at their breaking sites, which were host integration motifs (HIMs). We also predicted HIMs of eight circles from other ichnoviruses, indicating that a HIM-mediated specific mechanism was conserved in IV integrations. Investigation of DsIV circle insertion sites of the host genome revealed the enrichment of microhomologies between the host genome and the DsIV circles at integration breakpoints. These findings will deepen our understanding of the infections of PDVs, especially IVs.
多分DNA病毒（PDVs）分为两个属，即杆状病毒（BVs）和卵菌病毒（IVs），是大型双链DNA病毒，是寄生蜂的有益共生体。PDVs不会在其感染的鳞翅目宿主中复制。已经证明，自然寄生后BV环会整合到宿主基因组DNA中。然而，IV环的整合情况在很大程度上仍然未知。在这里，我们分析了卵菌病毒（DsIV）在被寄生血细胞基因组DNA中的整合情况。我们发现DsIV环以非整合形式和整合形式存在于宿主血细胞中。此外，DsIV通过两种不同的策略将其DNA环保守地和随机地整合到宿主基因组中。我们还发现四个保守断裂环在其断裂位点共享相似的基序，其中包含两个反向互补重复序列，这些是宿主整合基序（HIMs）。我们还预测了来自其他卵菌病毒的八个环的HIMs，表明HIM介导的特定机制在IV整合中是保守的。对宿主基因组中DsIV环插入位点的研究揭示了宿主基因组与DsIV环在整合断点处微同源性的富集。这些发现将加深我们对PDVs，尤其是IVs感染的理解。
