Esmaeili Shadisadat, Swan David A, Jerome Keith R, Schiffer Joshua T, Walter Marius
Vaccine and Infectious Diseases Division, Fred Hutch Cancer Center, Seattle, WA, USA.
Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
bioRxiv. 2025 May 13:2025.05.13.653775. doi: 10.1101/2025.05.13.653775.
Herpes simplex virus 1 (HSV-1) infection of epithelial cells is lytic, while infection of neurons typically results in long-term latency. However, the rates at which HSV-1 replicates and spreads in epithelial cells versus neurons under low and high multiplicity of infection (MOI) conditions remain undefined. Identifying these rates requires the application of mathematical models to carefully designed viral kinetic experiments. It is also critical to differentiate the dynamics of infectious viral particles versus viral DNA, as both quantities are routinely measured in experiments and human studies using plaque assays and polymerase chain reactions, respectively. Here, we developed mechanistic mathematical models to describe HSV-1 dynamics after infection of epithelial Vero cells and neuronal N2A cells, at high (3) and low (0.01) MOI. Our model recapitulates the dynamics of cell-free and cell-associated viral DNA and plaque-forming units (PFU). In epithelial cells, the model describes a pre-productive eclipse phase with a mean duration of 10.9 and 12.8 hours prior to HSV DNA replication and PFU production, respectively. Cells exited the eclipse phase as early and late as 2.5 and 32 hours, respectively. Infected cells produced a single PFU for every 224 HSV DNA genomes. PFU egressed at a constant rate, whereas the HSV DNA egress rate increased over time, before saturating at a 15 times higher rate. Under low relative to high MOI conditions, Vero cells spent 7 hours longer in the eclipse phase, had a 12-hour delay prior to egress, and had a longer mean duration of productive infection (14 versus 3.5-hour half-life). Secondary epithelial cell infection in low MOI experiments was overwhelmingly due to cell-to-cell viral spread and originated from a small number of early-producer cells. Neuronal cells produced viruses at a 5-fold lower rate and had a longer (mean: 42 hours) and more variable eclipse phase, with some neurons remaining in eclipse for more than a week. Our results highlighted large differences in HSV egress rates, as well as infected cell eclipse phase duration and death rates, in epithelial cells versus neurons during low and high MOI infection. The observed viral dynamics in neurons reflect a balance between active replication and latency.
单纯疱疹病毒1型（HSV-1）感染上皮细胞呈裂解性，而感染神经元通常导致长期潜伏。然而，在低和高感染复数（MOI）条件下，HSV-1在上皮细胞与神经元中的复制和传播速率仍不明确。确定这些速率需要将数学模型应用于精心设计的病毒动力学实验。区分感染性病毒颗粒与病毒DNA的动态变化也至关重要，因为在实验和人体研究中，这两个量通常分别使用噬斑测定法和聚合酶链反应进行测量。在此，我们建立了机械数学模型，以描述在高（3）和低（0.01）MOI条件下，HSV-1感染上皮Vero细胞和神经元N2A细胞后的动态变化。我们的模型概括了无细胞和细胞相关病毒DNA以及噬斑形成单位（PFU）的动态变化。在上皮细胞中，该模型描述了一个生产前的隐蔽期，在HSV DNA复制和PFU产生之前，平均持续时间分别为10.9小时和12.8小时。细胞分别最早在2.5小时和最晚在32小时退出隐蔽期。每224个HSV DNA基因组，受感染细胞产生一个PFU。PFU以恒定速率释放，而HSV DNA释放速率随时间增加，在达到高15倍的速率后饱和。在低MOI相对于高MOI条件下，Vero细胞在隐蔽期多花费7小时，在释放前延迟12小时，并且生产性感染的平均持续时间更长（半衰期为14小时对3.5小时）。低MOI实验中继发性上皮细胞感染绝大多数是由于细胞间病毒传播，并且起源于少数早期产生细胞。神经元细胞产生病毒的速率低5倍，并且具有更长（平均：42小时）和更可变的隐蔽期，一些神经元在隐蔽期持续超过一周。我们的结果突出了在低和高MOI感染期间，上皮细胞与神经元在HSV释放速率、受感染细胞隐蔽期持续时间和死亡率方面的巨大差异。在神经元中观察到的病毒动态反映了活跃复制与潜伏之间的平衡。
