He B, Leser G P, Paterson R G, Lamb R A
Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois, 60208-3500, USA.
Virology. 1998 Oct 10;250(1):30-40. doi: 10.1006/viro.1998.9354.
The SH gene of the paramyxovirus SV5 is located between the genes for the glycoproteins, fusion protein (F) and hemagglutinin-neuraminidase (HN), and the SH gene encodes a small 44-residue hydrophobic integral membrane protein (SH). The SH protein is expressed in SV5-infected cells and is oriented in membranes with its N terminus in the cytoplasm. To study the function of the SH protein in the SV5 virus life cycle, the SH gene was deleted from the infectious cDNA clone of the SV5 genome. By using the recently developed reverse genetics system for SV5, it was found that an SH-deleted SV5 (rSV5DeltaSH) could be recovered, indicating the SH protein was not essential for virus viability in tissue culture. Analysis of properties of rSV5DeltaSH indicated that lack of expression of SH protein did not alter the expression level of the other virus proteins, the subcellular localization of F and HN, or fusion competency as measured by lipid mixing assays and a new content mixing assay that did not require the use of vaccinia virus. The growth rate, infectivity, and plaque size of rSV5 and rSV5DeltaSH were found to be very similar. Although SH is shown to be a component of purified virions by immunoblotting, examination of purified rSV5DeltaSH by electron microscopy did not show an altered morphology from SV5. Thus in tissue culture cells the lack of the SV5 SH protein does not confer a recognizable phenotype.
副粘病毒SV5的SH基因位于糖蛋白、融合蛋白（F）和血凝素神经氨酸酶（HN）的基因之间，该SH基因编码一个由44个氨基酸组成的小的疏水整合膜蛋白（SH）。SH蛋白在感染SV5的细胞中表达，并且在膜中呈N端位于细胞质中的取向。为了研究SH蛋白在SV5病毒生命周期中的功能，从SV5基因组的感染性cDNA克隆中删除了SH基因。通过使用最近开发的SV5反向遗传学系统，发现可以回收缺失SH的SV5（rSV5DeltaSH），这表明SH蛋白对于组织培养中的病毒生存力并非必不可少。对rSV5DeltaSH特性的分析表明，SH蛋白的缺失并未改变其他病毒蛋白的表达水平、F和HN的亚细胞定位，或通过脂质混合测定和一种无需使用痘苗病毒的新的内容物混合测定所测量的融合能力。发现rSV5和rSV5DeltaSH的生长速率、感染性和蚀斑大小非常相似。尽管通过免疫印迹显示SH是纯化病毒粒子的一个组分，但通过电子显微镜检查纯化的rSV5DeltaSH并未显示出与SV5有改变的形态。因此，在组织培养细胞中，SV5 SH蛋白的缺失并未赋予可识别的表型。
