Neuroinflammation and Senescence Are Detected in Brainstems of Mice Latently Infected with HSV-1.

Following acute infection, herpes simplex virus type 1 (HSV-1) establishes life-long latency in neurons. Although sensory neurons in trigeminal ganglia (TG) are primary sites for latency, the brainstem is also an important site for latency. The rationale for examining the principal sensory nucleus of the spinal trigeminal tract (Pr5) receives afferent inputs from TG. Notably, the (LC) is indirectly linked to Pr5. Our previous studies revealed that senescent cells and inflammation were detected in the Pr5 and LC of aged mice and young mice that are latently infected with HSV-1. To expand our understanding of how HSV-1 influences senescence and inflammation in Pr5 and LC, NanoString studies in mice latently infected with wild-type HSV-1 or a latency-associated transcript (LAT) null mutant (dLAT2903) was compared to age-matched uninfected C57Bl/6 male and female mice. LAT is the only viral gene abundantly expressed during latency, suggesting it influences cellular gene expression during latency. Cellular genes that regulate neuron differentiation, axonal projection, and pro-inflammatory mediators were more prevalent in mice latently infected with wild-type (wt) HSV-1 and dLAT2903 versus uninfected mice. Finally, these studies revealed that latency in Pr5 and LC is a dynamic process.