Hanna Sheri L, Pierson Theodore C, Sanchez Melissa D, Ahmed Asim A, Murtadha Mariam M, Doms Robert W
Department of Microbiology, University of Pennsylvania, 225 Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA.
J Virol. 2005 Nov;79(21):13262-74. doi: 10.1128/JVI.79.21.13262-13274.2005.
West Nile virus (WNV) encodes two envelope proteins, premembrane (prM) and envelope (E). While the prM protein of all WNV strains contains a single N-linked glycosylation site, not all strains contain an N-linked site in the E protein. The presence of N-linked glycosylation on flavivirus E proteins has been linked to virus production, pH sensitivity, and neuroinvasiveness. Therefore, we examined the impact of prM and E glycosylation on WNV assembly and infectivity. Similar to other flaviviruses, expression of WNV prM and E resulted in the release of subviral particles (SVPs). Removing the prM glycosylation site in a lineage I or II strain decreased SVP release, as did removal of the glycosylation site in a lineage I E protein. Addition of the E protein glycosylation site in a lineage II strain that lacked this site increased SVP production. Similar results were obtained in the context of either reporter virus particles (RVPs) or infectious lineage II WNV. RVPs or virions bearing combinations of glycosylated and nonglycosylated forms of prM and E could infect mammalian, avian, and mosquito cells (BHK-21, QT6, and C6/36, respectively). Those particles lacking glycosylation on the E protein were modestly more infectious per genome copy on BHK-21 and QT6 cells, while this absence greatly enhanced the infection of C6/36 cells. Thus, glycosylation of WNV prM and E proteins can affect the efficiency of virus release and infection in a manner that is cell type and perhaps species dependent. This suggests a multifaceted role for envelope N-linked glycosylation in WNV biology and tropism.
西尼罗河病毒（WNV）编码两种包膜蛋白，即前膜蛋白（prM）和包膜蛋白（E）。虽然所有WNV毒株的prM蛋白都含有一个单一的N - 连接糖基化位点，但并非所有毒株的E蛋白都含有N - 连接位点。黄病毒E蛋白上N - 连接糖基化的存在与病毒产生、pH敏感性和神经侵袭性有关。因此，我们研究了prM和E糖基化对WNV组装和感染性的影响。与其他黄病毒类似，WNV prM和E的表达导致亚病毒颗粒（SVP）的释放。去除I型或II型毒株中的prM糖基化位点会减少SVP的释放，去除I型E蛋白中的糖基化位点也会有同样的效果。在缺乏该位点的II型毒株中添加E蛋白糖基化位点会增加SVP的产生。在报告病毒颗粒（RVP）或感染性II型WNV的情况下也获得了类似的结果。携带糖基化和非糖基化形式的prM和E组合的RVP或病毒粒子可以感染哺乳动物、禽类和蚊子细胞（分别为BHK - 21、QT6和C6/36）。那些E蛋白缺乏糖基化的颗粒在BHK - 21和QT6细胞上每个基因组拷贝的感染性略高，而这种缺失极大地增强了对C6/36细胞的感染。因此，WNV prM和E蛋白的糖基化可以以细胞类型甚至物种依赖的方式影响病毒释放和感染的效率。这表明包膜N - 连接糖基化在WNV生物学和嗜性中具有多方面的作用。
