Luo Kai-Jun, Pang Yi
State Key Laboratory of Biocontrol and Institute of Entomology, Sun Yat-Sen University, Guangzhou 510275, China.
Acta Biochim Biophys Sin (Shanghai). 2006 Aug;38(8):577-85. doi: 10.1111/j.1745-7270.2006.00195.x.
Microplitis bicoloratus is a braconid endoparasitic wasp associated with the polydnavirus named Microplitis bicoloratus bracovirus (MbBV). Parasitism of Spodoptera litura larvae leads to an impaired cellular immune response and to the disappearance of the 42 kDa actin in host hemocytes. In this work, we investigated if the absence of actin in blood cells was related to MbBV infection. An MbBV gene similar to egf-like genes identified in another bracovirus was partially cloned and named Mbcrp1. The full-length gene, named Mbcrp, is transcribed throughout the course of parasitism in host hemocytes and the 30 kDa MbCRP protein was detected in hemocytes 6-7 d post-parasitization. The Mbcrp1 gene contains the cysteine-rich trypsin inhibitor-like (TIL) domain coding sequence and the expression of recombinant MbCRP1 inhibited the expression of the 42 kDa actin in Hi5 cells. The 34.1 kDa MbCRP1-green fluorescent protein fusion protein locate specifically in the cytoplasm. These results suggest that expression of MbCRP in lepidopteran insect cells is related to the disruption of the actin cytoskeleton.
双色微颚茧蜂是一种与名为双色微颚茧蜂杆状病毒（MbBV）的多DNA病毒相关的茧蜂科内寄生蜂。对斜纹夜蛾幼虫的寄生会导致细胞免疫反应受损以及宿主血细胞中42 kDa肌动蛋白的消失。在这项研究中，我们调查了血细胞中肌动蛋白的缺失是否与MbBV感染有关。一个与在另一种杆状病毒中鉴定出的表皮生长因子样基因相似的MbBV基因被部分克隆并命名为Mbcrp1。全长基因命名为Mbcrp，在宿主血细胞寄生过程中全程转录，并且在寄生后6 - 7天在血细胞中检测到30 kDa的MbCRP蛋白。Mbcrp1基因包含富含半胱氨酸的类胰蛋白酶抑制剂（TIL）结构域编码序列，重组MbCRP1的表达抑制了Hi5细胞中42 kDa肌动蛋白的表达。34.1 kDa的MbCRP1 - 绿色荧光蛋白融合蛋白特异性定位于细胞质中。这些结果表明MbCRP在鳞翅目昆虫细胞中的表达与肌动蛋白细胞骨架的破坏有关。
