Resolution of herpes simplex virus reactivation in vivo results in neuronal destruction
Resolution of herpes simplex virus reactivation in vivo results in neuronal destruction
复制标题
DOI：
10.1371/journal.ppat.1008296
复制
发表时间：
2020-03-01
期刊：
影响因子：
6.7
通讯作者：
Sawtell, Nancy M.
中科院分区：
文献类型：
--
作者：
Doll, Jessica R.;Hoebe, Kasper;Sawtell, Nancy M.
单纯疱疹病毒 (HSV) 发病机制的一个基本问题是病毒对神经元重新激活的结果。支持重新激活后生存和死亡的证据已发表。感觉神经节神经元水平上的这一事件极其罕见，限制了对这一重要问题的直接检查。在这项研究中，对再激活的分辨率进行了深入的体内分析。通过高温应激诱导潜伏感染的 C57BL/6 小鼠在体内重新激活。在重新激活刺激后 20 小时，在这些小鼠的三叉神经节中检测到感染性病毒的比例很高（60-80%），但在刺激后 48 小时下降（0-13%）。随着重新激活刺激后时间的增加，被细胞袖带包围的重新激活神经元的百分比增加，这与可检测到的感染性病毒和病毒蛋白阳性神经元数量的减少相关。重要的是，除了完整的病毒蛋白阳性神经元之外，还检测到了形态上与凋亡小体一致且含有裂解的 caspase-3 的碎片病毒蛋白阳性神经元。这种表型的频率随着重新激活后的时间而增加。这些碎片化的神经元被 Iba1(+) 细胞包围，这与死亡神经元的吞噬清除一致。再激活后神经元破坏的证据促使人们重新审视之前报道的 T 细胞在控制再激活中的非溶细胞作用。在诱导再激活之前，用抗 CD4/CD8 抗体治疗潜伏感染的小鼠。感染性病毒滴度和神经元碎片都没有改变。相反，当病毒DNA复制在重新激活过程中被阻断时，即使病毒蛋白表达，也没有观察到片段化。我们的数据表明，至少一部分重新激活的神经元被破坏。尽管没有证据表明在此过程中直接 T 细胞介导的抗原识别，但抑制病毒 DNA 复制可阻止神经元断裂。这些意外的发现提出了关于宿主神经系统中 HSV 重新激活的解决方案的新问题。 作者摘要 单纯疱疹病毒 (HSV) 是一种人类地方性病原体，它在神经元中建立潜伏期，并可以在宿主的一生中定期重新激活。神经元在重新激活后是否存活存在争议，并且对长期感染具有重大影响。 HSV 再激活事件可以在小鼠中进行表征，小鼠维持宿主与病原体相互作用的复杂性，目的是深入了解病毒在神经系统中的行为。该报告表明，感染性病毒在体内重新激活后的消除与高度集中的细胞反应和含有 HSV 蛋白的神经元的破坏相对应。研究人员研究了 T 细胞在这种反应中的作用。先前的工作确定 T 细胞是 HSV 重新激活的主要调节因子。然而，当 T 细胞抗原识别辅助受体不存在并且感染性病毒滴度和病毒传播与同种型处理的对照神经节没有不同时，仍然观察到神经元破坏。相反，当病毒DNA复制受到抑制时，没有观察到表达病毒蛋白的神经元受到破坏。这些发现表明，重新激活是通过破坏神经元来解决的，这似乎与抗原介导的 T 细胞的细胞毒性无关，但确实需要病毒复制。
A fundamental question in herpes simplex virus (HSV) pathogenesis is the consequence of viral reactivation to the neuron. Evidence supporting both post-reactivation survival and demise is published. The exceedingly rare nature of this event at the neuronal level in the sensory ganglion has limited direct examination of this important question. In this study, an in-depth in vivo analysis of the resolution of reactivation was undertaken. Latently infected C57BL/6 mice were induced to reactivate in vivo by hyperthermic stress. Infectious virus was detected in a high percentage (60-80%) of the trigeminal ganglia from these mice at 20 hours post-reactivation stimulus, but declined by 48 hours post-stimulus (0-13%). With increasing time post-reactivation stimulus, the percentage of reactivating neurons surrounded by a cellular cuff increased, which correlated with a decrease in detectable infectious virus and number of viral protein positive neurons. Importantly, in addition to intact viral protein positive neurons, fragmented viral protein positive neurons morphologically consistent with apoptotic bodies and containing cleaved caspase-3 were detected. The frequency of this phenotype increased through time post-reactivation. These fragmented neurons were surrounded by Iba1(+) cells, consistent with phagocytic removal of dead neurons. Evidence of neuronal destruction post-reactivation prompted re-examination of the previously reported non-cytolytic role of T cells in controlling reactivation. Latently infected mice were treated with anti-CD4/CD8 antibodies prior to induced reactivation. Neither infectious virus titers nor neuronal fragmentation were altered. In contrast, when viral DNA replication was blocked during reactivation, fragmentation was not observed even though viral proteins were expressed. Our data demonstrate that at least a portion of reactivating neurons are destroyed. Although no evidence for direct T cell mediated antigen recognition in this process was apparent, inhibition of viral DNA replication blocked neuronal fragmentation. These unexpected findings raise new questions about the resolution of HSV reactivation in the host nervous system.Author summaryHerpes simplex virus (HSV) is an endemic human pathogen that establishes latency in neurons and can periodically reactivate over the lifetime of the host. Whether or not neurons survive post-reactivation is controversial and has significant implications for long-term infection. HSV reactivation events can be characterized in mice, which maintain the complexity of host-pathogen interactions, with the goal to provide insight into how the virus behaves in the nervous system. In this report, it is shown that the elimination of infectious virus following reactivation in vivo corresponded with a highly focused cellular response and destruction of the neuron containing HSV proteins. The role of T cells in this response was investigated. Previous work identified T cells as major regulators of HSV reactivation. However, neuronal destruction was still observed when T cell antigen recognition co-receptors were absent and infectious virus titers and viral spread was not different from isotype treated control ganglia. Conversely, destruction of viral protein expressing neurons was not observed when viral DNA replication was inhibited. These findings suggest that reactivation is resolved through destruction of the neuron, which appears to be independent of antigen-mediated T cell cytotoxicity, but does require viral replication.