Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota, USA.
J Virol. 2024 Nov 19;98(11):e0123224. doi: 10.1128/jvi.01232-24. Epub 2024 Oct 21.
During virus replication in cultured cells, copy-back defective viral genomes (cbDVGs) can arise. CbDVGs are powerful inducers of innate immune responses , but their occurrence and impact on natural infections of human hosts remain poorly defined. We asked whether cbDVGs were generated in the brain of a patient who succumbed to subacute sclerosing panencephalitis (SSPE) about 20 years after acute measles virus (MeV) infection. Previous analyses of 13 brain specimens of this patient indicated that a collective infectious unit (CIU) drove lethal MeV spread. In this study, we identified 276 replication-competent cbDVG species, each present in over 100 copies in the brain. Six species were detected in multiple forebrain locations, implying that they travelled long-distance with the CIU. The cbDVG to full-length genomes ratio was often close to 1 (0.6-1.74). Most cbDVGs were 324-2,000 bases in length, corresponding to 2%-12% of the full-length genome; all are predicted to have complementary terminal sequences. If improperly encapsidated, these sequences have the potential to form double-stranded structures that can induce innate immune responses. To assess this, we examined the transcriptome of all brain specimens. Several interferon and inflammatory response genes were upregulated, but upregulation levels did not correlate with cbDVG levels in the specimens. Thus, the CIU that drove MeV pathogenesis in this brain includes, in addition to two complementary full-length genome populations, many locally restricted and few widespread cbDVG species. The widespread cbDVG species may have been positively selected but how they impacted pathogenesis remains to be determined.IMPORTANCECopy-back defective viral genomes (cbDVGs) can drive virus-host interactions. They can suppress virus replication directly, by competing with full-length genomes, or indirectly by stimulating antiviral immunity. , cbDVG can slow down infections and promote persistence, but there is limited documentation of their presence in human hosts or of their impact on disease. We had the unique opportunity to analyze the brain of a patient who succumbed to subacute sclerosing panencephalitis, a rare but lethal consequence of measles. We detected more than 270 distinct cbDVG species; most were restricted to one specimen, but several reached all lobes of the forebrain, suggesting positive selection. Our analyses provide the missing knowledge of the diversity of cbDVG in a natural infection of a human host. They also reveal that a collective infectious unit that caused lethal human brain disease includes few widespread cbDVG, in addition to two ubiquitous complementary full-length genome populations.
在培养细胞中的病毒复制过程中，可能会出现反向复制缺陷病毒基因组（cbDVG）。cbDVG 是先天免疫反应的强大诱导物，但它们在人类宿主自然感染中的发生和影响仍未得到明确界定。我们想知道，在急性麻疹病毒（MeV）感染约 20 年后死于亚急性硬化性全脑炎（SSPE）的患者的大脑中是否产生了 cbDVG。先前对该患者 13 个脑标本的分析表明，一个集体感染单位（CIU）驱动致死性 MeV 传播。在这项研究中，我们鉴定了 276 种具有复制能力的 cbDVG 种，每种在大脑中的存在超过 100 个拷贝。六种在多个前脑部位被检测到，这意味着它们与 CIU 一起远距离传播。cbDVG 与全长基因组的比例通常接近 1（0.6-1.74）。大多数 cbDVG 的长度为 324-2000 个碱基，占全长基因组的 2%-12%；所有的预测都有互补的末端序列。如果包装不当，这些序列有可能形成可以诱导先天免疫反应的双链结构。为了评估这一点，我们检查了所有脑标本的转录组。一些干扰素和炎症反应基因上调，但上调水平与标本中的 cbDVG 水平无关。因此，驱动该脑 MeV 发病机制的 CIU 除了两个互补的全长基因组群体外，还包括许多局部受限和少数广泛传播的 cbDVG 种。广泛传播的 cbDVG 种可能是被正选择的，但它们如何影响发病机制仍有待确定。
重要性
反向复制缺陷病毒基因组（cbDVG）可以驱动病毒-宿主相互作用。它们可以通过与全长基因组竞争直接抑制病毒复制，或者通过刺激抗病毒免疫间接抑制病毒复制。此外，cbDVG 可以减缓感染并促进持续存在，但关于它们在人类宿主中的存在或对疾病的影响的文献有限。我们有机会分析一个死于亚急性硬化性全脑炎的患者的大脑，这是麻疹的一种罕见但致命的后果。我们检测到超过 270 种不同的 cbDVG 种；大多数局限于一个标本，但有几种标本到达前脑的所有叶，这表明存在正选择。我们的分析提供了在人类宿主自然感染中 cbDVG 多样性的缺失知识。它们还表明，导致致命人类大脑疾病的集体感染单位除了两个普遍存在的互补全长基因组群体外，还包括少数广泛传播的 cbDVG。
