del Rio T, Werner H C, Enquist L W
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
J Virol. 2002 Jan;76(2):774-82. doi: 10.1128/jvi.76.2.774-782.2002.
The tegument of herpesvirus virions is a distinctive structure whose assembly and function are not well understood. The herpes simplex virus type 1 VP22 tegument protein encoded by the UL49 gene is conserved among the alphaherpesviruses. Using cell biology and viral genetics, we provide an initial characterization of the pseudorabies virus (PRV) VP22 homologue. We identified three isoforms of VP22 present in PRV-infected cells that can be resolved by polyacrylamide gel electrophoresis. The predominant form is not phosphorylated and is present in virions, while the other two species are phosphorylated and excluded from virions. VP22 localized to the nucleus by 6 h postinfection, as determined by immunofluorescence and cell fractionation. VP22 immunofluorescence in the nucleus was both diffuse and in punctate structures. The punctate nuclear localization was the most pronounced form of staining and did not localize exclusively to sites of viral DNA replication. Unexpectedly, a VP22 null mutant had no obvious phenotypes during tissue culture infections and was similar to the wild type in all respects. Moreover, the VP22 null mutant was as virulent and neuroinvasive as the wild-type virus after infection of the rodent eye and spread to the brain using both anterograde and retrograde neuronal circuits.
疱疹病毒病毒粒子的包膜是一种独特的结构,其组装和功能尚未完全了解。由UL49基因编码的单纯疱疹病毒1型VP22包膜蛋白在α疱疹病毒中是保守的。利用细胞生物学和病毒遗传学,我们对伪狂犬病病毒(PRV)VP22同源物进行了初步表征。我们鉴定出PRV感染细胞中存在的三种VP22同工型,它们可以通过聚丙烯酰胺凝胶电泳分离。主要形式未被磷酸化,存在于病毒粒子中,而其他两种形式被磷酸化并被排除在病毒粒子之外。通过免疫荧光和细胞分级分离确定,感染后6小时VP22定位于细胞核。细胞核中的VP22免疫荧光呈弥漫性和点状结构。点状核定位是最明显的染色形式,并不完全定位于病毒DNA复制位点。出乎意料的是,VP22缺失突变体在组织培养感染期间没有明显的表型,并且在所有方面都与野生型相似。此外,VP22缺失突变体在感染啮齿动物眼睛后,通过顺行和逆行神经元回路传播到大脑,其毒力和神经侵袭性与野生型病毒相同。