The Early Gene hhi1 Reactivates Heliothis zea Nudivirus 1 in Latently Infected Cells
The Early Gene hhi1 Reactivates Heliothis zea Nudivirus 1 in Latently Infected Cells
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DOI：
10.1128/jvi.01548-09
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发表时间：
2010-01-15
影响因子：
5.4
通讯作者：
Chao, Yu-Chan
中科院分区：
文献类型：
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作者：
Wu, Yueh-Lung;Wu, Carol P.;Chao, Yu-Chan
Heliothis zea nudivirus 1 (HzNV-1)，以前称为hz1病毒，是一种昆虫病毒，能够在几种鳞翅目昆虫细胞中建立生产和潜伏感染。在这里，我们克隆并鉴定了HzNV-1的一个早期基因hhi1，它映射到病毒基因组的hindii - i片段。在产性病毒感染期间，早在感染后0.5 h （hpi）就可检测到6.2 kb的hhi1转录物。转录本水平在2 hpi时达到最大值，4 hpi后逐渐下降。在病毒感染的潜伏期，转录本无法检测到。在环己亚胺处理后，在整个高产病毒感染周期中检测到更高水平的hhi1转录物，这表明hhi1的表达不需要新合成的蛋白质。然而，病毒共感染可以进一步刺激转染的hhi1启动子在质粒中的表达。潜伏感染细胞中短暂的hhi1表达导致病毒滴度和病毒DNA繁殖显著增加，表明hhi1在病毒再激活中起关键作用。进一步的实验表明，转染hhi1后，潜伏细胞中有6个可能在转录或DNA复制中起作用的早期基因被激活。在这6个基因中，orf90和orf121可以由hhi1单独诱导表达，而不需要其他病毒基因。我们的发现将有助于未来HzNV-1潜伏/产生型病毒感染开关的机制研究。
Heliothis zea nudivirus 1 (HzNV-1), previously known as Hz-1 virus, is an insect virus able to establish both productive and latent infections in several lepidopteran insect cells. Here, we have cloned and characterized one of the HzNV-1 early genes, hhi1, which maps to the HindIII-I fragment of the viral genome. During the productive viral infection, a 6.2-kb hhi1 transcript was detectable as early as 0.5 h postinfection (hpi). The level of transcript reached a maximum at 2 hpi and gradually decreased after 4 hpi. The transcript was not detectable during the latent phase of viral infection. Upon cycloheximide treatment, much higher levels of hhi1 transcript were detected throughout the productive viral infection cycle, suggesting that newly synthesized proteins are not needed for the expression of hhi1. Nevertheless, viral coinfection can further stimulate the expression of transfected hhi1 promoter in a plasmid. Transient hhi1 expression in latently infected cells resulted in a significant increase in virus titer and viral DNA propagation, suggesting that hhi1 plays a critical role in viral reactivation. Additional experiments showed that six early genes, which possibly function in transcription or DNA replication, were activated in the latent cells upon hhi1 transfection. Among these six genes, orf90 and orf121 expression could be induced by hhi1 alone without the need for other viral genes. Our discovery should be useful for future mechanistic study of the switches of latent/productive HzNV-1 viral infections.