Bowles D E, Holden V R, Zhao Y, O'Callaghan D J
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932, USA.
J Virol. 1997 Jul;71(7):4904-14. doi: 10.1128/JVI.71.7.4904-4914.1997.
To assess the role of the equine herpesvirus type 1 (EHV-1) ICP0 protein (EICP0) in gene regulation, a variety of molecular studies on the EICP0 gene and gene products of both the attenuated cell culture-adapted Kentucky A (KyA) strain and the Ab4p strain were conducted. These investigations revealed that (i) the ICP0 open reading frame (ORF) of the KyA virus strain is 1,257 bp in size and would encode a protein of 419 amino acids, and in comparison to the ICP0 gene (ORF63) of the Ab4p strain of 1,596 bp (E. A. Telford, M. S. Watson, K. McBride, and A. J. Davison, Virology 189:304-316, 1992), it has an internal in-frame deletion of 339 bp; (ii) one early transcript of 1.4 kb predicted to encode the EICP0 protein and a late transcript of 1.8 kb are detected in Northern blot analyses using probes containing the EICP0 ORF; (iii) the KyA EICP0 protein (50 kDa) and the Ab4p EICP0 protein (80 kDa) are expressed as several species of early proteins that are first detected at 3 to 4 h postinfection by Western blot analyses of infected-cell polypeptides, using an antiserum generated to a TrpE fusion protein that harbors amino acids 46 to 153 of the EICP0 protein; and (iv) the EICP0 protein of both EHV-1 strains is a potent transactivator of EHV-1 genes. Transient expression assays using a simian virus 40 expression construct of the EICP0 protein of the KyA strain showed that the EICP0 protein independently transactivated chloramphenicol acetyltransferase reporter constructs under the control of the immediate-early promoter (3.9-fold), the early thymidine kinase promoter (95-fold), the late (gamma1) IR5 promoter (85-fold), and the late (gamma2) glycoprotein K promoter (21-fold). The finding that the EICP0 protein of the KyA virus can function as an activator of gene expression indicates that amino acids corresponding to residues 319 to 431 of the Ab4p EICP0 protein are not essential for EICP0 transactivation of EHV-1 promoters.
为了评估1型马疱疹病毒（EHV-1）的感染性细胞蛋白0（ICP0）蛋白（EICP0）在基因调控中的作用，针对减毒的细胞培养适应株肯塔基A（KyA）株和Ab4p株的EICP0基因及基因产物进行了多种分子研究。这些研究揭示：（i）KyA病毒株的ICP0开放阅读框（ORF）大小为1257 bp，编码一个419个氨基酸的蛋白质，与Ab4p株1596 bp的ICP0基因（ORF63）（E.A.特尔福德、M.S.沃森、K.麦克布赖德和A.J.戴维森，《病毒学》189:304 - 316，1992）相比，它有一个339 bp的框内内部缺失；（ii）在使用包含EICP0 ORF的探针进行的Northern印迹分析中，检测到一个预测编码EICP0蛋白的1.4 kb早期转录本和一个1.8 kb的晚期转录本；（iii）KyA EICP0蛋白（50 kDa）和Ab4p EICP0蛋白（80 kDa）表达为几种早期蛋白，在感染后3至4小时首次通过对感染细胞多肽的Western印迹分析检测到，使用针对包含EICP0蛋白第46至153位氨基酸的TrpE融合蛋白产生的抗血清；（iv）两种EHV-1株的EICP0蛋白都是EHV-1基因的有效反式激活因子。使用KyA株EICP0蛋白的猿猴病毒40表达构建体进行的瞬时表达分析表明，EICP0蛋白在立即早期启动子（3.9倍）、早期胸苷激酶启动子（95倍）、晚期（γ1）IR5启动子（85倍）和晚期（γ2）糖蛋白K启动子（21倍）的控制下独立反式激活氯霉素乙酰转移酶报告构建体。KyA病毒的EICP0蛋白可作为基因表达激活因子的这一发现表明，与Ab4p EICP0蛋白第319至431位残基对应的氨基酸对于EHV-1启动子的EICP0反式激活并非必需。
