May Janet S, Coleman Heather M, Smillie Belinda, Efstathiou Stacey, Stevenson Philip G
Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
J Gen Virol. 2004 Jan;85(Pt 1):137-146. doi: 10.1099/vir.0.19599-0.
A regulated switch between latent and lytic gene expression is common to all known herpesviruses. However, the effects on host colonization of altering this switch are largely unknown. We deregulated the transcription of the gene encoding the major lytic transactivator of murine gammaherpesvirus-68, ORF50, by inserting a new and powerful promoter element in its 5' untranslated region. In vitro, the mutant virus (M50) transcribed ORF50 at a high level and showed more rapid lytic spread in permissive fibroblast cultures, but in vivo, the M50 virus showed a severe deficit in latency establishment, with no sign of the infectious mononucleosis-like illness normally associated with wild-type infection. Although a low level of M50 viral DNA was detectable by PCR in spleens, replication-competent virus could not be recovered beyond 10 days post-infection. The M50 virus was also attenuated in immunocompromised mice. Thus a gammaherpesvirus unable to shut off lytic cycle gene expression showed severely restricted host colonization.
在所有已知的疱疹病毒中，潜伏和裂解基因表达之间的调控转换是常见的。然而，改变这种转换对宿主定殖的影响在很大程度上尚不清楚。我们通过在编码小鼠γ-疱疹病毒68主要裂解反式激活因子ORF50的基因的5'非翻译区插入一个新的强效启动子元件，使其转录失调。在体外，突变病毒（M50）高水平转录ORF50，并在允许的成纤维细胞培养物中显示出更快的裂解传播，但在体内，M50病毒在潜伏建立方面存在严重缺陷，没有通常与野生型感染相关的传染性单核细胞增多症样疾病的迹象。尽管通过PCR在脾脏中可检测到低水平的M50病毒DNA，但在感染后10天以上无法回收具有复制能力的病毒。M50病毒在免疫受损小鼠中也减弱。因此，一种无法关闭裂解周期基因表达的γ-疱疹病毒显示出宿主定殖受到严重限制。
