A recent scientific study has shown that certain viral diseases can contribute to the prevalence of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. The research, published by the health-focused site "Boldsky," citing the journal Nature Communications, relies on laboratory experiments demonstrating that specific viral particles facilitate the spread of protein aggregates known to be characteristic of brain diseases.
The research team from the University of Bonn in Germany observed that the aggregates of misfolded proteins, which occur in what is known as prion disease, have the capacity to transfer from one cell to another, thereby passing their abnormal shape to similar type proteins. The researchers stated that as a result, the disease spreads throughout the brain, and a similar phenomenon happens in Alzheimer’s and Parkinson’s disease. The transmission of the aggregates may involve direct contact from one cell to another, the release of "naked" clusters in the extracellular space, or packaging in vesicles, which are small bubbles surrounded by a lipid membrane released for cell-to-cell communication. Professor Ina Forberg from the University of Bonn noted that "the precise mechanisms of transmission are unknown."
To mimic the effects of viral infection, the researchers prompted the cells to produce viral proteins that mediate the binding and fusion of target cells. They selected two types of proteins, including the spike protein of SARS-CoV-2, which comes from the virus that causes COVID-19, and the glycoprotein of Vesicular Stomatitis Virus (VSV-G), which occurs in pathogens that affect cattle and other animals. The cells expressed receptors for these viral proteins, specifically a family of LDL receptors that stabilize VSV-G, along with ACE2 receptors for the SARS-CoV-2 protein. Professor Forberg stated, "We can demonstrate that viral proteins are integrated into both the cell membrane and extracellular vesicles." She added that "their presence increased the spread of the protein aggregate between cells, either through direct cell contact or via extracellular vesicles."
The viral links mediated the effective transport of aggregates to the recipient cells, triggering new aggregates. Professor Forberg explained, "The links act like keys that unlock the recipient cells and infiltrate the danger points."
Overall, the data suggest that the interactions between viral receptor links may fundamentally affect the transmission of pathological proteins. Professor Forberg commented, "The brains of patients with neurodegenerative diseases sometimes contain certain viruses. It is suspected that these may cause inflammation or have toxic effects, thus accelerating neurodegeneration," indicating that "viral proteins may act differently, as they might enhance the spread between cells of pre-existing protein aggregates in neurodegenerative diseases like Alzheimer's."
