Schwartz Jennifer A, Brittle Elizabeth E, Reynolds Ashley E, Enquist Lynn W, Silverstein Saul J
Department of Microbiology, Columbia University, 701 W. 168th St., New York, NY 10032, USA.
J Virol. 2006 Jan;80(2):769-84. doi: 10.1128/JVI.80.2.769-784.2006.
The pseudorabies virus (PRV) UL54 homologs are important multifunctional proteins with roles in shutoff of host protein synthesis, transactivation of virus and cellular genes, and regulation of splicing and translation. Here we describe the first genetic characterization of UL54. We constructed UL54 null mutations in a PRV bacterial artificial chromosome using sugar suicide and lambdaRed allele exchange systems. Surprisingly, UL54 is dispensable for growth in tissue culture but exhibits a small-plaque phenotype that can be complemented in trans by both the herpes simplex virus type 1 ICP27 and varicella-zoster virus open reading frame 4 proteins. Deletion of UL54 in the virus vJSdelta54 had no effect on the ability of the virus to shut off host cell protein synthesis but did affect virus gene expression. The glycoprotein gC accumulated to lower levels in cells infected with vJSdelta54 compared to those infected with wild-type virus, while gK levels were undetectable. Other late gene products, gB, gE, and Us9, accumulated to higher levels than those seen in cells infected with wild-type virus in a multiplicity-dependent manner. DNA replication is also reduced in cells infected with vJSdelta54. UL54 appears to regulate UL53 and UL52 at the transcriptional level as their respective RNAs are decreased in cells infected with vJSdelta54. Interestingly, vJSdelta54 is highly attenuated in a mouse model of PRV infection. Animals infected with vJSdelta54 survive twice as long as animals infected with wild-type virus, and this results in delayed accumulation of virus-specific antigens in skin, dorsal root ganglia, and spinal cord tissues.
伪狂犬病病毒（PRV）UL54同源物是重要的多功能蛋白，在宿主蛋白合成的关闭、病毒和细胞基因的反式激活以及剪接和翻译的调控中发挥作用。在此，我们描述了UL54的首次遗传学特征。我们使用糖自杀和lambdaRed等位基因交换系统在PRV细菌人工染色体中构建了UL54无效突变。令人惊讶的是，UL54对于在组织培养中的生长是可有可无的，但表现出小斑块表型，可被单纯疱疹病毒1型ICP27和水痘带状疱疹病毒开放阅读框4蛋白反式互补。病毒vJSdelta54中UL54的缺失对病毒关闭宿主细胞蛋白合成的能力没有影响，但确实影响病毒基因表达。与感染野生型病毒的细胞相比，感染vJSdelta54的细胞中糖蛋白gC积累到较低水平，而gK水平无法检测到。其他晚期基因产物gB、gE和Us9以多重依赖性方式积累到比感染野生型病毒的细胞中更高的水平。感染vJSdelta54的细胞中DNA复制也减少。UL54似乎在转录水平上调节UL53和UL52，因为在感染vJSdelta54的细胞中它们各自的RNA减少。有趣的是，vJSdelta54在PRV感染的小鼠模型中高度减毒。感染vJSdelta54的动物存活时间是感染野生型病毒动物的两倍，这导致病毒特异性抗原在皮肤、背根神经节和脊髓组织中的积累延迟。
