Department of Biology and Center for Tissue Regeneration and Engineering, University of Dayton, Dayton, Ohio, USA.
J Virol. 2013 Nov;87(21):11894-907. doi: 10.1128/JVI.01356-13. Epub 2013 Aug 28.
Baculoviridae is a large family of double-stranded DNA viruses that selectively infect insects. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the best-studied baculovirus from the family. Many studies over the last several years have shown that AcMNPV can enter a wide variety of mammalian cells and deliver genetic material for foreign gene expression. While most animal viruses studied so far have developed sophisticated mechanisms to selectively infect specific cells and tissues in an organism, AcMNPV can penetrate and deliver foreign genes into most cells studied to this date. The details about the mechanisms of internalization have been partially described. In the present study, we have identified a cholesterol recognition amino acid consensus (CRAC) domain present in the AcMNPV envelope fusion protein GP64. We demonstrated the association of a CRAC domain with cholesterol, which is important to facilitate the anchoring of the virus at the mammalian cell membrane. Furthermore, this initial anchoring favors AcMNPV endocytosis via a dynamin- and clathrin-dependent mechanism. Under these conditions, efficient baculovirus-driven gene expression is obtained. In contrast, when cholesterol is reduced from the plasma membrane, AcMNPV enters the cell via a dynamin- and clathrin-independent mechanism. The result of using this alternative internalization pathway is a reduced level of baculovirus-driven gene expression. This study is the first to document the importance of a novel CRAC domain in GP64 and its role in modulating gene delivery in AcMNPV.
杆状病毒科是一类具有双链 DNA 的病毒，它们选择性地感染昆虫。苜蓿银纹夜蛾多核型多角体病毒（AcMNPV）是该科研究得最好的杆状病毒。近年来的许多研究表明，AcMNPV 可以进入多种哺乳动物细胞，并传递外源基因进行表达。虽然迄今为止研究的大多数动物病毒都开发了复杂的机制来选择性地感染生物体中的特定细胞和组织，但 AcMNPV 可以穿透并将外源基因递送到迄今为止研究过的大多数细胞中。关于内化机制的细节已经部分描述。在本研究中，我们鉴定出 AcMNPV 包膜融合蛋白 GP64 中存在胆固醇识别氨基酸共识（CRAC）结构域。我们证明了 CRAC 结构域与胆固醇的结合，这对于促进病毒在哺乳动物细胞膜上的锚定是很重要的。此外，这种最初的锚定有利于 AcMNPV 通过网格蛋白和动力蛋白依赖的机制进行内吞作用。在这些条件下，可获得有效的杆状病毒驱动的基因表达。相比之下，当质膜中的胆固醇减少时，AcMNPV 通过网格蛋白和动力蛋白非依赖的机制进入细胞。使用这种替代内化途径的结果是杆状病毒驱动的基因表达水平降低。本研究首次证明了 GP64 中的新型 CRAC 结构域及其在调节 AcMNPV 基因传递中的作用的重要性。
