Chen Ya-Feng, Shi Min, Liu Peng-Cheng, Huang Fang, Chen Xue-Xin
Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Arch Insect Biochem Physiol. 2008 Jun;68(2):71-8. doi: 10.1002/arch.20253.
Cotesia vestalis (Braconidae, Hymenoptera) depends mainly on 3 regulatory factors to manipulate its host's development and immune response, including polydnavirus, venom, and teratocytes, among which polydnavirus plays a key role in suppressing the host immune system. In the present work, we cloned the full sequence of gene CvBV-ank2, encoding an IkappaB-like protein in C. vestalis polydnavirus (CvBV). The full sequence of CvBV-ank2 is 955 bp, encoding 162 amino acids with a calculated molecular mass of 18,355 Da. CvBV-ank2 shares high similarity with the exon I and exon II of CvBV-ank1, which is on the same segment with CvBV-ank2. This result suggests that gene duplication might occur in CvBV-ank1 and CvBV-ank2. Phylogenetic analysis indicated that CvBV-ank2 and CvBV-ank1, both on segment CvBV-S2, are, respectively, closely related with CcBV-26.3 and CcBV-26.2, both on segment Circle26 of C. congregata polydnavirus (CcBV). BLAST search using the sequence of segment CvBV-S2 as a query revealed that segment CvBV-S2 shares 90% max identity with segment Circle26 of CcBV over 67% query coverage. These results demonstrate that there is not only gene similarity, but also segment similarity between CvBV and CcBV. Transcripts of CvBV-ank2 were detected as early as 0.5 h post-parasitization and continued to be detected for 6 days, indicating that CvBV-ank2 might be involved in the early protection of the parasitoid egg.
菜蛾盘绒茧蜂（茧蜂科，膜翅目）主要依靠3种调节因子来操控其寄主的发育和免疫反应，包括多分DNA病毒、毒液和畸形细胞，其中多分DNA病毒在抑制寄主免疫系统中起关键作用。在本研究中，我们克隆了菜蛾盘绒茧蜂多分DNA病毒（CvBV）中编码类IκB蛋白的基因CvBV-ank2的全长序列。CvBV-ank2的全长序列为955 bp，编码162个氨基酸，计算分子量为18355 Da。CvBV-ank2与位于同一片段的CvBV-ank1的外显子I和外显子II具有高度相似性。这一结果表明CvBV-ank1和CvBV-ank2可能发生了基因重复。系统发育分析表明，位于CvBV-S2片段上的CvBV-ank2和CvBV-ank1分别与聚集菜蛾多分DNA病毒（CcBV）的Circle26片段上的CcBV-26.3和CcBV-26.2密切相关。以CvBV-S2片段序列为查询序列进行BLAST搜索发现，CvBV-S2片段与CcBV的Circle26片段在67%的查询覆盖范围内最大同一性为90%。这些结果表明，CvBV和CcBV之间不仅存在基因相似性，还存在片段相似性。早在寄生后0.5小时就检测到了CvBV-ank2的转录本，并且在6天内持续检测到，这表明CvBV-ank2可能参与了寄生蜂卵的早期保护。
