Objective Adeno-associated virus (AAV) is a defective mono-stranded DNA virus, endemic in human population (35%–80%). Recurrent clonal AAV2 insertions are associated with the pathogenesis of rare human hepatocellular carcinoma (HCC) developed on normal liver. This study aimed to characterise the natural history of AAV infection in the liver and its consequence in tumour development. Design Viral DNA was quantified in tumour and non-tumour liver tissues of 1461 patients. Presence of episomal form and viral mRNA expression were analysed using a DNAse/TaqMan-based assay and quantitative RT-PCR. In silico analyses using viral capture data explored viral variants and new clonal insertions. Results AAV DNA was detected in 21% of the patients, including 8% of the tumour tissues, equally distributed in two major viral subtypes: one similar to AAV2, the other hybrid between AAV2 and AAV13 sequences. Episomal viral forms were found in 4% of the non-tumour tissues, frequently associated with viral RNA expression and human herpesvirus type 6, the candidate natural AAV helper virus. In 30 HCC, clonal AAV insertions were recurrently identified in CCNA2, CCNE1, TERT, TNFSF10, KMT2B and GLI1/INHBE. AAV insertion triggered oncogenic overexpression through multiple mechanisms that differ according to the localisation of the integration site. Conclusion We provided an integrated analysis of the wild-type AAV infection in the liver with the identification of viral genotypes, molecular forms, helper virus relationship and viral integrations. Clonal AAV insertions were positive selected during HCC development on non-cirrhotic liver challenging the notion of AAV as a non-pathogenic virus.

中文翻译：

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肝脏中的腺相关病毒：自然史和肿瘤发展的后果

目的腺相关病毒（AAV）是一种有缺陷的单链 DNA 病毒，在人群中流行（35%–80%）。复发性克隆 AAV2 插入与在正常肝脏上发生的罕见人类肝细胞癌 (HCC) 的发病机制有关。本研究旨在表征肝脏中 AAV 感染的自然史及其在肿瘤发展中的后果。设计病毒 DNA 在 1461 名患者的肿瘤和非肿瘤肝组织中进行了量化。使用基于 DNAse/TaqMan 的测定和定量 RT-PCR 分析游离形式和病毒 mRNA 表达的存在。使用病毒捕获数据的计算机分析探索了病毒变体和新的克隆插入。结果 在 21% 的患者中检测到 AAV DNA，包括 8% 的肿瘤组织，平均分布在两种主要的病毒亚型中：一种类似于 AAV2，AAV2 和 AAV13 序列之间的另一种杂交。在 4% 的非肿瘤组织中发现了附加型病毒形式，通常与病毒 RNA 表达和人类疱疹病毒 6 型（候选天然 AAV 辅助病毒）有关。在 30 例 HCC 中，在 CCNA2、CCNE1、TERT、TNFSF10、KMT2B 和 GLI1/INHBE 中反复发现克隆 AAV 插入。AAV 插入通过多种机制触发致癌过度表达，这些机制因整合位点的定位而异。结论我们提供了肝脏中野生型 AAV 感染的综合分析，包括病毒基因型、分子形式、辅助病毒关系和病毒整合的鉴定。在非肝硬化肝脏的 HCC 发展过程中，克隆 AAV 插入被阳性选择，这挑战了 AAV 作为非致病病毒的概念。