HSV-1 Infection Alters Splicing and Promotes Tau Pathology in Neural Models of Alzheimer's Disease.

Introduction: Herpes simplex virus 1 (HSV-1) infection alters critical markers of Alzheimer's Disease (AD) in neurons. One key marker of AD is the hyperphosphorylation of Tau, accompanied by altered levels of Tau isoforms. However, an imbalance in these Tau splice variants, specifically resulting from altered 3R to 4R splicing of exon 10, has yet to be directly associated with HSV-1 infection.

Methods: To this end, we infected 2D and 3D human neural models with HSV-1 and monitored splicing and Tau phosphorylation. Further, we transduced SH-SY5Y-neurons with HSV-1 ICP27 which alters RNA splicing to analyze if ICP27 alone is sufficient to induce altered exon 10 splicing.

Results: We show that HSV-1 infection induces altered splicing of exon 10, increasing 4R-Tau protein levels, Tau hyperphosphorylation, and Tau oligomerization.

Discussion: Our experiments reveal a novel link between HSV-1 infection and the development of cytopathic phenotypes linked with AD progression.

Highlights: HSV-1 infection in forebrain organoids reduces the neurite length of MAP2-positive neurons.HSV-1 infection increases Tau hyperphosphorylation in both two-month-old and four-month-old forebrain organoids. HSV-1 infection increases Exon 10 containing (4R) mRNA and 4R-Tau protein expression in both forebrain organoids and human SH-SY5Y-neurons. HSV-1 ICP27 is both necessary and sufficient to induce increased 4R mRNA and 4R-Tau protein expression in SH-SY5Y-neurons. HSV-1 infection increases Tau oligomerization in both forebrain organoids and SH-SY5Y-neurons.