Parkinson J E, Sanderson C M, Smith G L
Sir William Dunn School of Pathology, University of Oxford, United Kingdom.
Virology. 1995 Dec 1;214(1):177-88. doi: 10.1006/viro.1995.9942.
The vaccinia virus gene A38L encodes a highly hydrophobic protein with amino acid similarity to mammalian integrin-associated protein (IAP). In this report we have identified the A38L protein of strain Western Reserve (WR), defined its membrane topology, and analyzed its role in virus production and virulence. An antiserum raised against an A38L peptide identified the A38L gene product as a 33-kDa protein which is expressed at low levels during virus infection. A serum from a rabbit previously infected with WR virus recognized the A38L protein, thus confirming that the A38L gene is expressed in vivo. Using a coupled in vitro-translation/membrane-translocation system the 33-kDa protein was shown to be a membrane-associated and glycosylated form of a 29-kDa polypeptide precursor. The membrane topology of the A38L protein was defined by its glycosylation and protease sensitivity when associated with microsomal membranes. The N-terminal immunoglobulin-like variable domain was protected from exogenous protease and was therefore in the lumen of the vesicle, whereas the C-terminus was sensitive and therefore cytoplasmic. A38L deletion and revertant viruses were constructed and were used to study the involvement of A38L in virus assembly, release, and virulence. Deletion of the A38L gene caused a slight reduction in virus plaque size but did not affect the production of intracellular mature virus or extracellular enveloped virus particles in tissue culture cells nor the virulence of the virus in the murine intranasal model. The A38L protein therefore possesses similar sequence and membrane topology to the mammalian IAP protein but is not required for virus particle production or virulence.
痘苗病毒基因A38L编码一种高度疏水的蛋白质，其氨基酸序列与哺乳动物整合素相关蛋白（IAP）相似。在本报告中，我们鉴定了西储株（WR）的A38L蛋白，确定了其膜拓扑结构，并分析了其在病毒产生和毒力中的作用。针对A38L肽产生的抗血清鉴定出A38L基因产物是一种33 kDa的蛋白质，在病毒感染期间低水平表达。先前感染WR病毒的兔子血清识别出A38L蛋白，从而证实A38L基因在体内表达。使用体外翻译与膜转运偶联系统，显示33 kDa的蛋白质是29 kDa多肽前体的膜相关糖基化形式。当与微粒体膜结合时，A38L蛋白的膜拓扑结构由其糖基化和蛋白酶敏感性确定。N端免疫球蛋白样可变结构域对外源蛋白酶具有抗性，因此位于囊泡腔内，而C端敏感，因此位于细胞质中。构建了A38L缺失和回复病毒，并用于研究A38L在病毒组装、释放和毒力中的作用。A38L基因的缺失导致病毒蚀斑大小略有减小，但不影响组织培养细胞中细胞内成熟病毒或细胞外被膜病毒颗粒的产生，也不影响病毒在小鼠鼻内模型中的毒力。因此，A38L蛋白与哺乳动物IAP蛋白具有相似的序列和膜拓扑结构，但病毒颗粒产生或毒力并不需要它。
