Feng, YayanCao, Shu-QinShi, YiSun, AnnaFlanagan, Margaret E.Leverenz, James B.Pieper, Andrew A.Jung, Jae U.Cummings, JeffreyFang, Evandro FeiZhang, PengyueCheng, Feixiong2025-03-212025-03-212025Feng Y, Cao SQ, Shi Y, et al. Human herpesvirus-associated transposable element activation in human aging brains with Alzheimer's disease. Alzheimers Dement. 2025;21(2):e14595. doi:10.1002/alz.14595https://hdl.handle.net/1805/46441Introduction: Human herpesvirus (HHV) has been linked to Alzheimer's disease (AD), but the underlying mechanisms remain unknown. Methods: We leveraged functional genomics data from Religious Orders Study or the Rush Memory and Aging Project (ROS/MAP) and Mount Sinai Brain Bank (MSBB) brain biobanks and single-cell RNA-sequencing data from HHV-infected forebrain organoids to investigate HHV-infection-associated transposable element (TE) dysregulation underlying AD etiologies. Results: We identified widespread TE dysregulation in HHV-positive human AD brains, including an astrocyte-specific upregulation of LINE1 subfamily TEs in HHV-positive human AD brains. We further pinpointed astrocyte-specific LINE1 upregulation that could potentially regulate target gene NEAT1 expression via long-range enhancer-promoter chromatin interactions. This LINE1 dysregulation can be partially reversed by the usage of anti-HHV drugs (valacyclovir and acyclovir) in a virus-infected human brain organoid model. Finally, we demonstrated that valacyclovir rescued tau-associated neuropathology and alleviated LINE1 activation in an experimental tau aggregation model. Discussion: Our analysis provides associations linking molecular, clinical, and neuropathological AD features with HHV infection, which warrants future clinical validation. Highlights: Via analysis of bulk RNA-seq data in two large-scale human brain biobanks, ROS/MAP (n = 109 pathologically confirmed AD and n = 44 cognitively healthy controls) and MSBB (n = 284 AD and n = 150 cognitively healthy controls), we identified widespread TE activation in HHV-positive human AD brains and significantly positive associations of HHV RNA abundance with APOE4 genotype, Braak staging score, and CERAD score. We identified cell type-specific LINE1 upregulation in both microglia and astrocytes of human AD brains via long-range enhancer-promoter chromatin interactions on lncRNA nuclear enriched abundant transcript 1 (NEAT1). We determined that usage of valacyclovir and acyclovir was significantly associated with reduced incidence of AD in a large real-world patient database. Using the HEK293 tau P301S model and U2OS mt-Keima cell model, we determined that valacyclovir treatment rescued tau-associated neuropathology and alleviated activation of LINE1 with increased cellular autophagy-level mechanistically supported clinical benefits of valacyclovir in real-world patient data.en-USAttribution-NonCommercial-NoDerivatives 4.0 InternationalAlzheimer's disease (AD)Human herpesvirus (HHV)Long interspersed nuclear element 2 (LINE1)NeuroinflammationTransposable element (TE)ValacyclovirArticle