Promoter targeted histone acetylation of chromatinized parvoviral genome is essential for infrection progress

The association of host histones with parvoviral DNA is poorly understood. We analyzed the chromatinization and histone acetylation of canine parvovirus DNA during infection by confocal imaging and in situ proximity ligation assay combined with chromatin immunoprecipitation and high-throughput sequencing. We found that at late infection parvovirus replication bodies were rich in histones bearing modifications characteristic of transcriptionally active chromatin, i.e. histone H3 lysine acetylation (H3K27ac). The H3K27ac, in particular, was located in close proximity to the viral DNA-binding protein NS1. Importantly, our results show for the first time that in the chromatinized parvoviral genome, particularly the two viral promoters were rich in H3K27ac. Histone acetyltransferase (HAT) inhibitorefficiently interfered with expression of viral proteins and infection progress. Altogether, our data suggest that acetylation of histones on parvoviral DNA is essential for viral gene expression and completion of viral life cycle. Examination of H3K27 acetylation in CPV infected and non-infected NLFK (Norden laboratory feline kidney) cells. Please note that the result in this study, considering the sequencing, is the fact that the viral genome is chromatinized. Processed data in this case would be the aligned read percentages in control cells (of which 0% aligns to parvoviral genome) and infected cells (of which ~9% only aligns to parvoviral genome and not to the cat genome), which is basically the output of the read aligner software without further processing steps (no peaks or regions were identified for the associated publication). Therefore no processed data was provided, and an exception to GEO processed data requirement was made.

宿主组蛋白与细小病毒DNA的结合机制目前仍未得到充分阐明。本研究通过共聚焦成像（confocal imaging）、原位邻近连接试验（in situ proximity ligation assay）结合染色质免疫沉淀（chromatin immunoprecipitation）与高通量测序（high-throughput sequencing），分析了感染过程中犬细小病毒（canine parvovirus, CPV）DNA的染色质化状态与组蛋白乙酰化修饰情况。研究发现，在感染晚期，细小病毒复制灶富含带有转录活性染色质特征修饰的组蛋白，即组蛋白H3赖氨酸乙酰化修饰（H3K27ac）。尤为关键的是，H3K27ac修饰位点与病毒DNA结合蛋白NS1紧密相邻。值得注意的是，本研究首次证实，在染色质化的细小病毒基因组中，尤其是两个病毒启动子区域富集了H3K27ac修饰。组蛋白乙酰转移酶（histone acetyltransferase, HAT）抑制剂可有效抑制病毒蛋白的表达与感染进程。综上，本研究数据表明，细小病毒DNA结合的组蛋白乙酰化修饰对于病毒基因表达以及病毒生命周期的完成至关重要。本研究还对感染与未感染CPV的NLFK（Norden实验室猫肾细胞系，Norden laboratory feline kidney）细胞中的H3K27乙酰化水平进行了检测。需要说明的是，本研究基于测序得到的核心结果为病毒基因组发生了染色质化。本研究中的原始处理数据为比对读段的百分比：对照组细胞的读段比对率为0%（无非细小病毒基因组比对序列），感染组细胞中约9%的读段仅比对至细小病毒基因组，而非猫科动物基因组。该数据本质上为读段比对软件的直接输出结果，未经过进一步处理（本次关联发表未进行峰区或基因组区域的识别分析）。因此本研究未提供标准处理后数据，并针对GEO数据库的处理数据提交要求申请了例外豁免。