Flaviviruses are small enveloped virions that enter target cells in a pH-dependent fashion. Virus attachment, entry, and membrane fusion are orchestrated by the envelope (E) and pre-membrane (prM) proteins, the two structural proteins displayed on the surface of virions. Flaviviruses assemble as an immature non-infectious form onto which prM and E form trimeric spikes. During egress from infected cells, flaviviruses undergo dramatic structural changes characterized by the formation of a herringbone arrangement of E proteins that lie flat against the surface of the virion and cleavage of the prM protein by the cellular protease furin. The result is a relatively smooth, infectious mature virion. This dynamic process is now understood in structural detail at the atomic level. However, recent studies indicate that many of the virions released from cells share structural features of both immature and mature virus particles. These mosaic partially mature virions are infectious and interact uniquely with target cells and the host immune response. Here, we will discuss recent advances in our understanding of the biology and significance of partially mature flaviviruses.

黄病毒是小包膜病毒粒子，以 pH 依赖性方式进入靶细胞。病毒附着、进入和膜融合由包膜 (E) 和膜前 (prM) 蛋白协调，这两种结构蛋白显示在病毒粒子表面。黄病毒组装为未成熟的非传染性形式，prM 和 E 在其上形成三聚体尖峰。在从受感染细胞排出期间，黄病毒经历了戏剧性的结构变化，其特征是形成 E 蛋白的人字形排列，该蛋白平放在病毒粒子的表面上，并被细胞蛋白酶弗林蛋白酶切割 prM 蛋白。结果是相对平滑的、具有传染性的成熟病毒体。这个动态过程现在可以在原子级别的结构细节中得到理解。然而，最近的研究表明，许多从细胞释放的病毒粒子具有未成熟和成熟病毒颗粒的结构特征。这些镶嵌部分成熟的病毒粒子具有传染性，并与靶细胞和宿主免疫反应独特地相互作用。在这里，我们将讨论我们对部分成熟黄病毒的生物学和意义的理解的最新进展。