Sensory neurons in trigeminal ganglia (TG) of calves latently infected with bovine herpesvirus 1 (BoHV-1) abundantly express latency-related (LR) gene products, including a protein (ORF2) and two micro-RNAs. Recent studies in mouse neuroblastoma cells (Neuro-2A) demonstrated ORF2 interacts with β-catenin and a β-catenin coactivator, high-mobility group AT-hook 1 (HMGA1) protein, which correlates with increased β-catenin-dependent transcription and cell survival. β-Catenin and HMGA1 are readily detected in a subset of latently infected TG neurons but not TG neurons from uninfected calves or reactivation from latency. Consequently, we hypothesized that the Wnt/β-catenin signaling pathway is differentially expressed during the latency and reactivation cycle and an active Wnt pathway promotes latency. RNA-sequencing studies revealed that 102 genes associated with the Wnt/β-catenin signaling pathway were differentially expressed in TG during the latency-reactivation cycle in calves. Wnt agonists were generally expressed at higher levels during latency, but these levels decreased during dexamethasone-induced reactivation. The Wnt agonist bone morphogenetic protein receptor 2 (BMPR2) was intriguing because it encodes a serine/threonine receptor kinase that promotes neuronal differentiation and inhibits cell death. Another differentially expressed gene encodes a protein kinase (Akt3), which is significant because Akt activity enhances cell survival and is linked to herpes simplex virus 1 latency and neuronal survival. Additional studies demonstrated ORF2 increased Akt3 steady-state protein levels and interacted with Akt3 in transfected Neuro-2A cells, which correlated with Akt3 activation. Conversely, expression of Wnt antagonists increased during reactivation from latency. Collectively, these studies suggest Wnt signaling cooperates with LR gene products, in particular ORF2, to promote latency.

IMPORTANCE Lifelong BoHV-1 latency primarily occurs in sensory neurons. The synthetic corticosteroid dexamethasone consistently induces reactivation from latency in calves. RNA sequencing studies revealed 102 genes associated with the Wnt/β-catenin signaling pathway are differentially regulated during the latency-reactivation cycle. Two protein kinases associated with the Wnt pathway, Akt3 and BMPR2, were expressed at higher levels during latency but were repressed during reactivation. Furthermore, five genes encoding soluble Wnt antagonists and β-catenin-dependent transcription inhibitors were induced during reactivation from latency. These findings are important because Wnt, BMPR2, and Akt3 promote neurogenesis and cell survival, processes crucial for lifelong viral latency. In transfected neuroblastoma cells, a viral protein expressed during latency (ORF2) interacts with and enhances Akt3 protein kinase activity. These findings provide insight into how cellular factors associated with the Wnt signaling pathway cooperate with LR gene products to regulate the BoHV-1 latency-reactivation cycle.

潜伏感染牛疱疹病毒 1 (BoHV-1) 的小牛三叉神经节 (TG) 中的感觉神经元大量表达潜伏期相关 (LR) 基因产物，包括一种蛋白质 (ORF2) 和两种微 RNA。最近对小鼠神经母细胞瘤细胞 (Neuro-2A) 的研究表明，ORF2 与 β-catenin 和 β-catenin 共激活剂、高迁移率组 AT-hook 1 (HMGA1) 蛋白相互作用，这与 β-catenin 依赖性转录和细胞因子增加相关。生存。 β-连环蛋白和 HMGA1 在潜伏感染的 TG 神经元子集中很容易检测到，但在未感染的小牛或潜伏期重新激活的 TG 神经元中却检测不到。因此，我们假设 Wnt/β-catenin 信号通路在潜伏期和重新激活周期中有差异表达，并且活跃的 Wnt 通路会促进潜伏期。 RNA测序研究表明，在犊牛的潜伏期-再激活周期中，与Wnt/β-连环蛋白信号通路相关的102个基因在TG中存在差异表达。 Wnt 激动剂通常在潜伏期以较高水平表达，但这些水平在地塞米松诱导的重新激活期间下降。 Wnt 激动剂骨形态发生蛋白受体 2 (BMPR2) 很有趣，因为它编码丝氨酸/苏氨酸受体激酶，可促进神经元分化并抑制细胞死亡。另一个差异表达的基因编码蛋白激酶 (Akt3)，这很重要，因为 Akt 活性可增强细胞存活率，并与单纯疱疹病毒 1 潜伏期和神经元存活率相关。其他研究表明，ORF2 增加了 Akt3 稳态蛋白水平，并在转染的 Neuro-2A 细胞中与 Akt3 相互作用，这与 Akt3 激活相关。相反，Wnt 拮抗剂的表达在潜伏期重新激活期间增加。 总的来说，这些研究表明 Wnt 信号传导与 LR 基因产物（特别是 ORF2）协同作用，以促进潜伏期。

重要性BoHV-1 终生潜伏期主要发生在感觉神经元中。合成皮质类固醇地塞米松持续诱导犊牛从潜伏期重新激活。 RNA 测序研究表明，与 Wnt/β-catenin 信号通路相关的 102 个基因在潜伏期-再激活周期中受到差异性调节。与 Wnt 通路相关的两种蛋白激酶 Akt3 和 BMPR2 在潜伏期表达水平较高，但在重新激活过程中受到抑制。此外，编码可溶性Wnt拮抗剂和β-连环蛋白依赖性转录抑制剂的五个基因在从潜伏期重新激活期间被诱导。这些发现很重要，因为 Wnt、BMPR2 和 Akt3 促进神经发生和细胞存活，这些过程对于终生病毒潜伏期至关重要。在转染的神经母细胞瘤细胞中，潜伏期表达的病毒蛋白 (ORF2) 与 Akt3 蛋白激酶活性相互作用并增强其活性。这些发现让我们深入了解与 Wnt 信号通路相关的细胞因子如何与 LR 基因产物配合调节 BoHV-1 潜伏-再激活周期。