Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
J Virol. 2013 Apr;87(7):3862-70. doi: 10.1128/JVI.03222-12. Epub 2013 Jan 23.
Human papillomavirus 16 (HPV16) enters its host cells by a process that most closely resembles macropinocytosis. Uncoating occurs during passage through the endosomal compartment, and the low pH encountered in this environment is essential for infection. Furin cleavage of the minor capsid protein, L2, and cyclophilin B-mediated separation of L2 and the viral genome from the major capsid protein, L1, are necessary for escape from the late endosome (LE). Following this exodus, L2 and the genome are found colocalized at the ND10 nuclear subdomain, which is essential for efficient pseudogenome expression. However, the route by which L2 and the genome traverse the intervening cytoplasm between these two subcellular compartments has not been determined. This study extends our understanding of this phase in PV entry in demonstrating the involvement of the Golgi complex. With confocal microscopic analyses involving 5-ethynyl-2'-deoxyuridine (EdU)-labeled pseudogenomes and antibodies to virion and cellular proteins, we found that the viral pseudogenome and L2 travel to the trans-Golgi network (TGN) following exit from the LE, while L1 is retained. This transit is dependent upon furin cleavage of L2 and can be prevented pharmacologically with either brefeldin A or golgicide A, inhibitors of anterograde and retrograde Golgi trafficking. Additionally, Rab9a and Rab7b were determined to be mediators of this transit, as expression of dominant negative versions of these proteins, but not Rab7a, significantly inhibited HPV16 pseudovirus infection.
人乳头瘤病毒 16（HPV16）通过最类似于巨胞饮的过程进入宿主细胞。脱壳发生在穿过内体隔室的过程中，该环境中的低 pH 值对于感染至关重要。次要衣壳蛋白 L2 的弗林切割，以及亲环素 B 介导的 L2 和病毒基因组与主要衣壳蛋白 L1 的分离，对于从晚期内体（LE）逃逸是必要的。在这种逃亡之后，L2 和基因组在 ND10 核亚域中发现共定位，这对于有效假基因组表达是必需的。然而，L2 和基因组穿过这两个细胞亚区之间的细胞质的途径尚未确定。这项研究通过证明高尔基体复合物的参与，扩展了我们对 PV 进入这一阶段的理解。通过涉及 5-乙炔基-2'-脱氧尿苷（EdU）标记的假基因组和针对病毒和细胞蛋白的抗体的共聚焦显微镜分析，我们发现病毒假基因组和 L2 在从 LE 中退出后，沿着过渡型高尔基体网络（TGN）移动，而 L1 则被保留。这种转运依赖于 L2 的弗林切割，并且可以通过布雷菲德菌素 A 或 golgicide A 药理学预防，这两种药物是顺行和逆行高尔基体运输的抑制剂。此外，Rab9a 和 Rab7b 被确定为这种转运的介质，因为表达这些蛋白的显性负形式，而不是 Rab7a，可显著抑制 HPV16 假病毒感染。
