Assembly of the Herpes Simplex Virus Capsid

1型单纯疱疹病毒（HSV 1）的衣壳是一个厚15nm，直径125nm的二十面体（T=16）蛋白壳。在完整的病毒中，衣壳包含病毒DNA，并被脂质膜包围。衣壳由一种叫做VP5的主要蛋白质组成，它约占总衣壳质量的70%，加上三种次要多肽，VP19， VP23和VP26。在受感染的细胞中，空的（无DNA的）衣壳在细胞核中组装，然后用DNA包装。pi最近开发了一种系统，可以在无细胞环境中组装HSV - 1衣壳。该系统需要使用六种不同的重组杆状病毒，每种病毒编码参与HSV - 1衣壳形成的六种蛋白质中的一种。这六种是上面提到的四种结构多肽加上支架蛋白（VP22a）和成熟蛋白酶（HSV 1 UL26基因的产物）。每种病毒用于感染单独的昆虫（Sf9）细胞培养物，并从每种培养物中制备无细胞提取物。当这六种额外的cts混合在一起时，HSV - 1衣壳会自发形成。P.I.计划研究该系统中衣壳形成的时间过程，以确定组装过程中的形态发生中间体。预计这些中间体的结构和组成以及它们在反应混合物中出现的次数将表明整个组装途径的基本特征。单纯疱疹病毒1型（HSV 1）是引起唇疱疹和发热水疱的病原体。传染性病毒由一种叫做衣壳的蛋白质外壳组成，被一层脂质膜包围。HSV - 1含有在衣壳内发现的DNA。当病毒在被感染的细胞中复制时，首先形成一个完整的空衣壳；然后用DNA包装，最后涂上一层膜。这个项目的目标是了解HSV - 1组装的第一步，即衣壳的形成。在这些研究中，参与衣壳组装的六种蛋白质在衣壳自发形成的条件下在体外混合在一起。P.I.建议使用该系统来识别装配过程中的中间体。预计这些中间体的结构和蛋白质组成以及它们出现的时间将表明整个组装途径的基本特征。

The capsid of herpes simplex virus type 1 (HSV 1) is an icosahedral (T=16) protein shell 15nm thick and 125nm in diameter. In the intact virus, the capsid contains the viral DNA and it is surrounded by a lipid membrane. The capsid is composed of a major protein species called VP5 which accounts for approximately 70% of the total capsid mass plus three minor polypeptides, VP19, VP23 and VP26. In infected cells, empty (DNA free) capsids are assembled in the cell nucleus and later packaged with DNA. The P.I. has recently developed a system in which the HSV 1 capsid can be assembled in a cell free environment. The system requires the use of six different recombinant baculoviruses each coding for one of the six proteins involved in HSV 1 capsid formation. The six are the four structural polypeptides mentioned above plus the scaffolding protein (VP22a) and the maturational protease (the product of the HSV 1 UL26 gene). Each virus is used to infect a separate culture of insect (Sf9) cells and cell free extracts are prepared from each culture. HSV 1 capsids form spontaneously when the six extra cts are mixed. The P.I. plans to study the time course of capsid formation in this system to identify morphogenetic intermediates in the assembly process. It is expected that the structure and composition of such intermediates and the times they appear in reaction mixtures will suggest the basic features of the overall assembly pathway. %%% Herpes simplex virus type 1 (HSV l) is the causative agent of cold sores and fever blisters. The infectious virus consists of a protein shell called the capsid surrounded by a lipid membrane. HSV l contains DNA which is found inside the capsid shell. When the virus is replicated in an infected cell, a complete, empty capsid is first formed; it is later packaged with DNA and finally coated with a membrane envelope. The goal of this project is to understand the first step in HSV l assembly, namely formation of the capsid. In these studies, the six proteins involved in capsid assembly are mixed together in vitro under conditions in which capsids form spontaneously. The P.I. proposes to use this system to identify intermediates in the assembly process. It is expected that the structure and protein composition of such intermediates and the times they appear will suggest the basic features of the overall assembly pathway.