Herpes simplex virus type 1 accumulation, envelopment, and exit in growth cones and varicosities in mid-distal regions of axons
Herpes simplex virus type 1 accumulation, envelopment, and exit in growth cones and varicosities in mid-distal regions of axons
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DOI：
10.1128/jvi.80.7.3592-3606.2006
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发表时间：
2006-04-01
影响因子：
5.4
通讯作者：
Cunningham, AL
中科院分区：
文献类型：
--
作者：
Saksena, MM;Wakisaka, H;Cunningham, AL
α疱疹病毒在轴突中顺行运输的机制仍存在争议。本研究使用共聚焦显微镜和透射电子显微镜 (TEM) 在感染后 19、24 和 48 小时 (p.i.) 检测了 1 型单纯疱疹病毒 (HSV-1) 在受感染的外植人类胎儿背根神经节的中远端轴突中的运输、组装和排出。共聚焦显微镜研究表明，尽管衣壳 (VP5) 和被膜 (UL37) 蛋白在注射后 24 小时之前并未均匀存在于轴突中，但在注射后 24 小时和 48 小时时，它们与轴突静脉曲张和生长锥中的包膜 (gG) 蛋白共定位。原位轴突纵向切片的 TEM 显示轴突静脉曲张和生长锥中有包膜和无包膜衣壳，而在轴突的中部区域，主要观察到无包膜衣壳。在轴突静脉曲张和生长锥中观察到部分包膜的衣壳，显然是出芽成囊泡，但在病毒附着和进入轴突期间没有观察到。通过透射免疫电子显微镜，发现皮层蛋白 (VP22) 与生长锥中的囊泡相关，单独或与包膜 (gD) 蛋白一起。在轴突静脉曲张和生长锥附近观察到细胞外病毒粒子，在轴突质膜的新月形内陷中观察到一些病毒粒子，表明在这些位点存在。这些发现表明，静脉曲张和生长锥可能是 HSV-1 包封中远轴突中至少一部分病毒粒子的可能位点。包膜可能是通过衣壳出芽进入具有相关外皮和包膜蛋白的囊泡而发生的。病毒粒子似乎通过胞吐作用从这些位点退出。
The mechanism of anterograde transport of alphaherpesviruses in axons remains controversial. This study examined the transport, assembly, and egress of herpes simplex virus type 1 (HSV-1) in mid- and distal axons of infected explanted human fetal dorsal root ganglia using confocal microscopy and transmission electron microscopy (TEM) at 19, 24, and 48 h postinfection (p.i.). Confocal-microscopy studies showed that although capsid (VP5) and tegument (UL37) proteins were not uniformly present in axons until 24 h p.i., they colocalized with envelope (gG) proteins in axonal varicosities and in growth cones at 24 and 48 h p.i. TEM of longitudinal sections of axons in situ showed enveloped and unenveloped capsids in the axonal varicosities and growth cones, whereas in the midregion of the axons, predominantly unenveloped capsids were observed. Partially enveloped capsids, apparently budding into vesicles, were observed in axonal varicosities and growth cones, but not during viral attachment and entry into axons. Tegument proteins (VP22) were found associated with vesicles in growth cones, either alone or together with envelope (gD) proteins, by transmission immunoelectron microscopy. Extracellular virions were observed adjacent to axonal varicosities and growth cones, with some virions observed in crescent-shaped invaginations of the axonal plasma membrane, suggesting exit at these sites. These findings suggest that varicosities and growth cones are probable sites of HSV-1 envelopment of at least a proportion of virions in the mid-to distal axon. Envelopment probably occurs by budding of capsids into vesicles with associated tegument and envelope proteins. Virions appear to exit from these sites by exocytosis.