Absence of IE1 p72 protein function during low-multiplicity infection by human cytomegalovirus results in a broad block to viral delayed-early gene expression
Absence of IE1 p72 protein function during low-multiplicity infection by human cytomegalovirus results in a broad block to viral delayed-early gene expression
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DOI：
10.1128/jvi.76.9.4441-4455.2002
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发表时间：
2002-05-01
影响因子：
5.4
通讯作者：
Greaves, RF
中科院分区：
文献类型：
--
作者：
Gawn, JM;Greaves, RF
人巨细胞病毒(HCMV)IE1缺失突变体CR208在原代成纤维细胞低度感染后存在严重的生长缺陷。此前，我们发现低复数感染CR208的细胞积累延迟早期(DE)蛋白ppUL44的细胞要比积累立即早期2(IE2)p86蛋白的细胞少得多，这表明流产感染的频率很高。我们现在证明，在没有IE1 P72的情况下，在低复数感染后，所有被测试的DE蛋白的积累是有缺陷的。在低复数CR208感染期间，DE蛋白pUL57、pUL98和pUL69的积累遵循与ppUL44非常相似的模式。在低复数CR208感染期间，与其他DE蛋白相比，ppUL112-113蛋白在细胞中积累的比例更大，但相对于野生型病毒来说仍然是不足的。我们还首次表明，在低复数CR208感染期间，许多DE RNA的稳态水平降低，通过丰富的细胞质2.7-kb TRL4 DE(beta2.7)RNA的原位杂交，病毒DE RNA遵循与ppUL44类似的缺陷积累模式。此外，瞬时检测中发现，转染的DE启动子-报告构建体对CR208感染的反应比对野生型汤恩病毒感染的反应要小得多。我们的结果表明，在缺乏功能IE1 P72的情况下，低复数HCMV感染后DE基因的表达普遍存在缺陷，这可能是由于DE基因转录减少和DE RNAs积累减少所致。
Human cytomegalovirus (HCMV) ie1 deletion mutant CR208 is profoundly growth deficient after low-multiplicity infection of primary fibroblasts. Previously, we showed that many fewer cells infected with CR208 at low multiplicity accumulated the delayed-early (DE) protein ppUL44 than accumulated the immediate-early 2 (IE2) p86 protein, indicating a high frequency of abortive infections. We now demonstrate that accumulation of all DE proteins tested was defective after low-multiplicity infection in the absence of IE1 p72. Accumulation of the DE proteins pUL57, pUL98, and pUL69 followed a pattern very similar to that of ppUL44 during low-multiplicity CR208 infection. Accumulation of the ppUL112-113 proteins occurred in a greater proportion of cells than other DE proteins during low-multiplicity CR208 infection, but was still deficient relative to wild-type virus. We also show for the first time that steady-state levels of many DE RNAs were reduced during low-multiplicity CR208 infection and that by in situ hybridization of the abundant cytoplasmic 2.7-kb TRL4 DE (beta2.7) RNA, a viral DE RNA followed a defective pattern of accumulation similar to that of ppUL44. Furthermore, transfected DE promoter-reporter constructs were found in transient assays to be considerably less responsive to CR208 infection than to infection by wild-type Towne virus. Our results indicate a general defect in DE gene expression following low-multiplicity HCMV infection in the absence of functional IE1 p72, most probably mediated by reduced transcription of DE genes and by the reduced accumulation of DE RNAs.