Institute of Virology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany.
Viruses. 2013 Apr 10;5(4):1075-98. doi: 10.3390/v5041075.
Like all other viruses, a successful egress of functional particles from infected cells is a prerequisite for foamy virus (FV) spread within the host. The budding process of FVs involves steps, which are shared by other retroviruses, such as interaction of the capsid protein with components of cellular vacuolar protein sorting (Vps) machinery via late domains identified in some FV capsid proteins. Additionally, there are features of the FV budding strategy quite unique to the spumaretroviruses. This includes secretion of non-infectious subviral particles and a strict dependence on capsid-glycoprotein interaction for release of infectious virions from the cells. Virus-like particle release is not possible since FV capsid proteins lack a membrane-targeting signal. It is noteworthy that in experimental systems, the important capsid-glycoprotein interaction could be bypassed by fusing heterologous membrane-targeting signals to the capsid protein, thus enabling glycoprotein-independent egress. Aside from that, other systems have been developed to enable envelopment of FV capsids by heterologous Env proteins. In this review article, we will summarize the current knowledge on FV budding, the viral components and their domains involved as well as alternative and artificial ways to promote budding of FV particle structures, a feature important for alteration of target tissue tropism of FV-based gene transfer systems.
与所有其他病毒一样，功能性颗粒从感染细胞中成功逸出是泡沫病毒（FV）在宿主中传播的前提。FV 的出芽过程涉及到其他逆转录病毒共有的步骤，例如衣壳蛋白通过某些 FV 衣壳蛋白中的晚期结构域与细胞液泡蛋白分选（Vps）机制的成分相互作用。此外，FV 出芽策略还有一些独特的特征，这包括非感染性亚病毒颗粒的分泌，以及严格依赖衣壳糖蛋白相互作用将感染性病毒粒子从细胞中释放出来。由于 FV 衣壳蛋白缺乏膜靶向信号，因此不可能释放病毒样颗粒。值得注意的是，在实验系统中，可以通过将异源膜靶向信号融合到衣壳蛋白上来绕过重要的衣壳糖蛋白相互作用，从而实现糖蛋白非依赖性出芽。除此之外，还开发了其他系统来使 FV 衣壳被异源 Env 蛋白包被。在这篇综述文章中，我们将总结目前关于 FV 出芽的知识，包括涉及的病毒成分及其结构域，以及促进 FV 颗粒结构出芽的替代和人工方法，这是改变基于 FV 的基因转移系统靶组织嗜性的重要特征。
