Barber Sheila A, Gama Lucio, Dudaronek Justyna M, Voelker Tauni, Tarwater Patrick M, Clements Janice E
Department of Comparative Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
J Infect Dis. 2006 Apr 1;193(7):963-70. doi: 10.1086/500983. Epub 2006 Feb 21.
The brain is considered to be a reservoir of latent human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). We examined the mechanism by which innate immune responses contribute to the establishment of this reservoir.
Gene-specific RNA and DNA were quantitated using real-time reverse-transcription polymerase chain reaction (RT-PCR). Protein expression was examined using Western blot analysis. Binding to and regulation of the SIV long terminal repeat (LTR) was examined using electrophoretic mobility shift assay, luciferase reporter constructs, and chromatin immunoprecipitation assay.
Interferon-beta (IFN-beta) and myxovirus A (MxA) mRNA are produced in the brain during acute SIV infection. IFN-beta both suppresses SIV LTR activity and induces expression of the dominant-negative isoform of CCAAT/enhancer-binding protein-beta (C/EBP-beta). C/EBP-beta and its dominant-negative isoform respectively enhance and suppress histone acetylation at the SIV LTR and are present at the SIV LTR in vivo. SIV DNA persists when viral RNA is undetectable in the brain, and activation of the LTR is suppressed at the level of histone acetylation.
Innate immune responses to virus infection that suppress acute virus replication in the brain also facilitate transcriptional latency of SIV. These data provide the first mechanistic model of HIV latency in the brain.
大脑被认为是人类免疫缺陷病毒（HIV）和猿猴免疫缺陷病毒（SIV）的潜伏库。我们研究了先天免疫反应促成该潜伏库建立的机制。
使用实时逆转录聚合酶链反应（RT-PCR）对基因特异性RNA和DNA进行定量。使用蛋白质印迹分析检测蛋白质表达。使用电泳迁移率变动分析、荧光素酶报告构建体和染色质免疫沉淀分析检测与SIV长末端重复序列（LTR）的结合及对其的调控。
在急性SIV感染期间，大脑中会产生干扰素-β（IFN-β）和黏液病毒A（MxA）mRNA。IFN-β既能抑制SIV LTR活性，又能诱导CCAAT/增强子结合蛋白-β（C/EBP-β）的显性负性异构体的表达。C/EBP-β及其显性负性异构体分别增强和抑制SIV LTR处的组蛋白乙酰化，且在体内存在于SIV LTR处。当大脑中检测不到病毒RNA时，SIV DNA持续存在，且LTR的激活在组蛋白乙酰化水平受到抑制。
对病毒感染的先天免疫反应在抑制大脑中急性病毒复制的同时，也促进了SIV的转录潜伏。这些数据提供了大脑中HIV潜伏的首个机制模型。
