Characterization of a Novel Golgi Apparatus-Localized Latency Determinant Encoded by Human Cytomegalovirus
Characterization of a Novel Golgi Apparatus-Localized Latency Determinant Encoded by Human Cytomegalovirus
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DOI：
10.1128/jvi.01989-08
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发表时间：
2009-06-01
影响因子：
5.4
通讯作者：
Goodrum, Felicia
中科院分区：
文献类型：
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作者：
Petrucelli, Alex;Rak, Michael;Goodrum, Felicia
人巨细胞病毒（HCMV）通过造血细胞中尚未明确的潜伏感染而无限期地存在于感染个体中。我们之前证明了推定的 UL138 开放阅读框 (ORF) 在促进体外感染的 CD34(+) 造血祖细胞 (HPC) 潜伏感染方面的需要。在我们目前的研究中，我们鉴定了两个 2.7 和 3.6 kb 的共末端转录物以及一个 21 千道尔顿 (kDa) 蛋白 (pUL138)，它们源自 UL138 位点，在生产性感染期间具有早期-晚期基因动力学。在成纤维细胞和 HPC 中均检测到 UL138 转录物和蛋白质。合成 UL138 转录物但不合成蛋白质的重组病毒 FIX-UL138(STOP) 在 HPC 中表现出部分潜伏期丧失表型，类似于在 UL138 无效重组病毒中观察到的表型。这一发现表明 UL138 蛋白是潜伏期所必需的，但并不排除 UL138 转录本或其他 ORF 也有助于潜伏期的可能性。 pUL138 导致潜伏期的机制仍不清楚。虽然在体外感染 HCMV 的 HPC 中未检测到 86-和 72-kDa 立即早期蛋白，但在报告基因检测中，pUL138 不能直接抑制主要立即早期启动子的表达。有趣的是，pUL138 定位于受感染细胞中的高尔基体，但不并入病毒颗粒中。 pUL138 定位于高尔基体表明 pUL138 通过一种新机制促进 HCMV 潜伏期。 pUL138 是第一个被证明可促进具有 CD34(+) HPC 潜伏期特征的感染的 HCMV 蛋白。
Human cytomegalovirus (HCMV) exists indefinitely in infected individuals by a yet poorly characterized latent infection in hematopoietic cells. We previously demonstrated a requirement for the putative UL138 open reading frame (ORF) in promoting a latent infection in CD34(+) hematopoietic progenitor cells (HPCs) infected in vitro. In our present study, we have identified two coterminal transcripts of 2.7 and 3.6 kb and a 21-kilodalton (kDa) protein (pUL138) that are derived from the UL138 locus with early-late gene kinetics during productive infection. The UL138 transcripts and protein are detected in both fibroblasts and HPCs. A recombinant virus, FIX-UL138(STOP), that synthesizes the UL138 transcripts but not the protein exhibited a partial loss-of-latency phenotype in HPCs, similar to the phenotype observed for the UL138-null recombinant virus. This finding suggests that the UL138 protein is required for latency, but it does not exclude the possibility that the UL138 transcripts or other ORFs also contribute to latency. The mechanisms by which pUL138 contributes to latency remain unknown. While the 86- and 72-kDa immediate-early proteins were not detected in HPCs infected with HCMV in vitro, pUL138 did not function directly to suppress expression from the major immediate-early promoter in reporter assays. Interestingly, pUL138 localizes to the Golgi apparatus in infected cells but is not incorporated into virus particles. The localization of pUL138 to the Golgi apparatus suggests that pUL138 contributes to HCMV latency by a novel mechanism. pUL138 is the first HCMV protein demonstrated to promote an infection with the hallmarks of latency in CD34(+) HPCs.