Investigation for signals and host factors related to paramyxovirus budding.

在本项目中，我们得到了如下结果：首先，通过共转染多个病毒蛋白，建立了与仙台病毒（SeV）相似的病毒样颗粒（VLPs）系统。通过该系统，我们发现辅助C蛋白具有促进VLP释放的能力。我们进一步证明了C蛋白与宿主因子AIP1/Alix相互作用，并且这种相互作用对于VLP的促进是必不可少的。其次，我们证实了M蛋白是颗粒从细胞中释放的驱动力，我们在M蛋白中发现了一个晚域基序，进一步证明了它与AIP1/Alix相互作用。Tsg101和Nedd4似乎都没有参与M蛋白的功能，但泛素和Vps4A参与了M蛋白的功能。因此，可能通过AIP1/Alix相互作用，M蛋白和C蛋白对病毒出芽都很重要。据推测，这种相互作用招募了转运所需的内体分选复合体（ESCRT）到病毒出芽。我们进一步确定了SeV蛋白与AIP1/Alix相互作用的氨基酸基序，并将产生携带不能与AIP1/Alix结合的突变的病毒，以证实和扩展我们的结果。如上所述，病毒蛋白对病毒出芽的重要作用、病毒蛋白的功能基序以及相关的宿主因子正在得到澄清。

In the present project, we obtained the results described below.Firstly, we established a system to generate virus-like particles (VLPs) similar to Sendai virus (SeV) by co-transfecting multiple viral proteins. By using the system, we found that the accessory C protein had an ability to facilitate VLP release. We further demonstrated that the C protein interacted a host factor, AIP1/Alix, and that the interaction was essential for the VLP facilitation.Secondly, we confirmed that the M protein is a driving force for the particle release from cells, and we identified a late domain motif in the M protein, which was further shown to interact with AIP1/Alix. Neither Tsg101 nor Nedd4 appeared to be involved in the M protein function, but ubiquitin and Vps4A were involved in it.Thus, both of the M and C proteins are important for virus budding probably by interacting AIP1/Alix. The interaction was presumed to recruit the endosome-sorting complex required for transport (ESCRT) to virus budding. We further identified amino acid motifs for the interaction between the SeV proteins and AIP/Alix, and will generate viruses carrying the mutations incompetent to binding with AIP1/Alix to confirm and extend our results. As described, viral proteins important virus budding, viral protein motifs for the function, and related host factors are being clarified.