Shi Min, Chen Ya-Feng, Huang Fang, Liu Peng-Cheng, Zhou Xue-Ping, Chen Xue-Xin
Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Virology. 2008 Jun 5;375(2):374-82. doi: 10.1016/j.virol.2008.02.027. Epub 2008 Mar 18.
Cotesia vestalis (Haliday) is an endoparasitoid of Plutella xylostella (L.) larvae and injects a polydnavirus (CvBV) into its host during oviposition. In this report we describe the characterization of a gene (CvBV805) and its products. CvBV805 is located on the segment S8 of CvBV genome; it has a size of 909 bp and encodes a predicted protein of 125 amino acids. This protein contains an ankyrin repeat domain with a high degree of similarity with IkappaB-like genes. Gene transcripts were detected in extracts of the host as early as 2 h post-parasitization (p.p.) and continued to be detected through 24 h. Tissue-specific expression patterns showed that CvBV805 might be involved in early host immunosuppression. CvBV805 was detected in parasitized hosts at 12 h p.p. and in rBac-eGFP-CvBV805-infected Tn-5B1-4 cells at 72 h.p.i. by using western blots analysis. The size of the protein expressed in the host hemocytes and infected Tn-5B1-4 cells was 17 kDa and 56 kDa (including eGFP), respectively, which nearly corresponded with the predicted molecular weight (14.31 kDa) of CvBV805, suggesting that the protein did not undergo extensive post-translational modification. The protein was confirmed to be present within the nuclear region in hemocytes of the parasitized P. xylostella larvae at 48 h p.p. using confocal laser scanning microscopy.
菜蛾盘绒茧蜂（Cotesia vestalis (Haliday)）是小菜蛾（Plutella xylostella (L.)）幼虫的一种内寄生蜂，在产卵时会将一种多角体病毒（CvBV）注入其宿主。在本报告中，我们描述了一个基因（CvBV805）及其产物的特征。CvBV805位于CvBV基因组的S8片段上；它的大小为909 bp，编码一个预测的125个氨基酸的蛋白质。该蛋白质包含一个锚蛋白重复结构域，与类IkappaB基因具有高度相似性。早在寄生后2小时（p.p.）就在宿主提取物中检测到了基因转录本，并且在24小时内持续被检测到。组织特异性表达模式表明，CvBV805可能参与宿主早期免疫抑制。通过蛋白质免疫印迹分析，在寄生后12小时的寄生宿主中以及在感染rBac-eGFP-CvBV805的Tn-5B1-4细胞中于感染后72小时（h.p.i.）检测到了CvBV805。在宿主血细胞和感染的Tn-5B1-4细胞中表达的蛋白质大小分别为17 kDa和56 kDa（包括eGFP），这与CvBV805预测的分子量（14.31 kDa）几乎相符，表明该蛋白质没有经历广泛的翻译后修饰。使用共聚焦激光扫描显微镜证实，在寄生后48小时的小菜蛾幼虫血细胞的核区域中存在该蛋白质。
