A possible viral trigger behind Alzheimer’s disease?
Alzheimer's disease has traditionally been associated with the accumulation of amyloid-beta (Aβ) plaques and abnormal tau proteins in the brain. Many researchers have also suggested that chronic inflammation plays an equally important role, particularly during the earliest stages.
One hypothesis links recurrent HSV-1 infections to an increased risk of cognitive decline. HSV-1 is extremely prevalent: following initial infection, the virus remains dormant but can periodically reactivate, specifically under stress conditions. Hence, the authors sought to understand the characteristics of HSV-1 with cognitive behavior.
Recreating repeated viral reactivation in the brain
To model disease progression, researchers infected mice with HSV-1 and induced viral reactivation through controlled thermal stress — two cycles to mimic early neurodegeneration, six to replicate an advanced Alzheimer's-like phenotype.
The team evaluated:
- memory performance
- synaptic plasticity
- Alzheimer's-related proteins such as amyloid-beta, phosphorylated tau and GSK-3β
Protein levels in hippocampal tissue were quantified by Western blot and dot blot using the Alliance Q9 imaging system (Uvitec Cambridge), enabling precise, reproducible densitometric quantification across all experimental groups.
Western blot analysis of GSK-3β activation in HSV-1-infected mice
a) Western blot analysis of phosphorylated GSK-3β (pGSK-3β) in hippocampal tissue from mock- and HSV-1–infected mice following six cycles of thermal stress. b) Treatment of HSV-1 with lithium chloride reduces GSK-3β activation. Western blot image extracted from Li Puma et al., 2026, Neural Regeneration Research.
A pathological shift at advanced stages
After 6 cycles, inflammation persisted but anti-inflammatory treatments that had previously restored brain function no longer worked. Instead, the dominant features became pronounced GSK-3β activation, amyloid-beta accumulation, and tau hyperphosphorylation. Inhibiting GSK-3β with lithium chloride significantly reduced these pathological markers, identifying this pathway as a promising therapeutic target for advanced disease.
This marks a clear shift: from an inflammation-driven early phase to a protein pathology-driven late phase.
Conclusion
Overall, these findings suggest that the biological mechanisms involved in Alzheimer's-like pathology may vary across disease stages. This shift highlights the need for further research into stage-specific therapeutic strategies. Future studies will determine whether similar mechanisms are also observed in humans.
Results at a glance
Glossary
Synaptic plasticity: The ability of connections between neurons to strengthen or weaken over time. It’s the biological mechanism underlying learning and memory formation.
Hippocampal tissue: Tissue from a brain region critical for memory and spatial navigation.
GSK-3β (Glycogen Synthase Kinase 3 beta): An enzyme that regulates multiple cellular processes. When overactivated, it triggers the abnormal phosphorylation of tau and APP, accelerating Alzheimer's-related protein accumulation.