Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Neuroscience Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Viruses. 2022 Jul 2;14(7):1464. doi: 10.3390/v14071464.
La Crosse virus (LACV) is a major cause of pediatric encephalitis and aseptic meningitis in the Midwestern, Mid-Atlantic, and Southern United States, where it is an emerging pathogen. The LACV Gc glycoprotein plays a critical role in the neuropathogenesis of LACV encephalitis as the putative virus attachment protein. Previously, we identified and experimentally confirmed the location of the LACV fusion peptide within Gc and generated a panel of recombinant LACVs (rLACVs) containing mutations in the fusion peptide as well as the wild-type sequence. These rLACVs retained their ability to cause neuronal death in a primary embryonic rat neuronal culture system, despite decreased replication and fusion phenotypes. To test the role of the fusion peptide in vivo, we tested rLACVs in an age-dependent murine model of LACV encephalitis. When inoculated directly into the CNS of young adult mice (P28), the rLACV fusion peptide mutants were as neurovirulent as the rLACV engineered with a wild-type sequence, confirming the results obtained in tissue culture. In contrast, the fusion peptide mutant rLACVs were less neuroinvasive when suckling (P3) or weanling (P21) mice were inoculated peripherally, demonstrating that the LACV fusion peptide is a determinant of neuroinvasion, but not of neurovirulence. In a challenge experiment, we found that peripheral challenge of weanling (P21) mice with fusion peptide mutant rLACVs protected from a subsequent WT-LACV challenge, suggesting that mutations in the fusion peptide are an attractive target for generating live-attenuated virus vaccines. Importantly, the high degree of conservation of the fusion peptide amongst the and, structurally, other arboviruses suggests that these findings are broadly applicable to viruses that use a class II fusion mechanism and cause neurologic disease.
拉科罗拉病毒（LACV）是美国中西部、大西洋中部和南部导致小儿脑炎和无菌性脑膜炎的主要原因，它是一种新兴病原体。LACV 的 Gc 糖蛋白作为假定的病毒附着蛋白，在 LACV 脑炎的神经发病机制中发挥关键作用。以前，我们鉴定并实验证实了 LACV 融合肽在 Gc 中的位置，并生成了一组包含融合肽突变和野生型序列的重组 LACV（rLACV）。尽管复制和融合表型降低，但这些 rLACV 仍保留在原代大鼠神经元培养系统中引起神经元死亡的能力。为了测试融合肽在体内的作用，我们在依赖年龄的 LACV 脑炎小鼠模型中测试了 rLACV。当直接接种到年轻成年小鼠（P28）的中枢神经系统中时，rLACV 融合肽突变体与具有野生型序列的 rLACV 一样具有神经毒力，证实了组织培养中获得的结果。相比之下，当幼鼠（P3）或断奶鼠（P21）进行外周接种时，融合肽突变体 rLACV 的神经侵袭性较弱，表明 LACV 融合肽是神经侵袭的决定因素，但不是神经毒力的决定因素。在一项挑战实验中，我们发现融合肽突变体 rLACV 对断奶鼠（P21）的外周挑战可预防随后的 WT-LACV 挑战，表明融合肽中的突变是生成活减毒病毒疫苗的有吸引力的靶标。重要的是，融合肽在 和其他虫媒病毒之间高度保守，结构上，提示这些发现广泛适用于使用 II 类融合机制并引起神经疾病的病毒。
