Viral Infection Triggers Parkinson’s Symptoms in Mice
Texas A&M University researchers have developed a novel model for studying Parkinson’s disease using the Theiler’s murine encephalomyelitis virus (TMEV). Published in the journal Brain, Behavior, and Immunity-Health, the study reveals that a viral infection can trigger both the loss of dopamine-producing cells and motor function deficits in mice, providing a non-toxic alternative to conventional chemical-based research.
Moving Beyond Chemical Toxicants
For decades, laboratories have relied on chemical toxicants or genetic modifications to induce Parkinson’s-like symptoms. These methods, while common, often fail to replicate the complex, multifactorial way the disease emerges in humans.
Candice Brinkmeyer-Langford, a neurodegenerative disease expert at the Texas A&M University School of Public Health, notes that toxic-exposure models fail to account for the reality that not everyone exposed to specific chemicals develops the condition. By employing TMEV—a pathogen natural to mice—the team created a model that simulates the neuroinflammation and physical degradation of Parkinson’s without the need for artificial toxins.
Quantifying Neurological and Motor Deficits
To validate the model, researchers tracked disease progression through rigorous neurological and motor assessments. The data confirmed that viral infection directly compromises the brain’s movement regulation:
- Dopamine Neuron Loss: Within one week of infection, the virus targeted dopamine-producing cells. By one month, researchers observed significant cell destruction, confirmed by administering a dopamine-mimicking drug that revealed distinct movement patterns in infected models compared to healthy controls.
- Motor Skill Impairment: Using a standard “pole test,” the team measured speed and coordination. Infected mice showed consistently slower completion times compared to healthy counterparts, a deficit that persisted through the 20-week study period.
- Gait and Balance Analysis: Utilizing a specialized treadmill, the team analyzed over 100 variables related to gait, balance, and walking efficiency. The results showed that the viral-induced loss of dopamine neurons led to measurable physical weakness and abnormal movement patterns, mirroring symptoms seen in human patients.
The Link Between Inflammation and Disease
Parkinson’s disease affects more than 10 million people globally, standing as the second most common brain disorder after dementia. While the exact cause remains unknown, the medical community has long hypothesized that brain inflammation—potentially triggered by viruses contracted years or even decades earlier—plays a role in the disease’s onset.
Brinkmeyer-Langford emphasizes that viruses can manifest differently depending on a person’s underlying genetics. This is similar to how the Epstein-Barr virus is linked to mononucleosis, multiple sclerosis, and certain cancers, or how SARS-CoV-2 has been shown to affect the brain and heart in addition to the respiratory system.
Identifying Early Biological Markers
With the TMEV model established, the Texas A&M team plans to conduct further studies to compare this approach against traditional research models. Future work will focus on identifying early biological markers for Parkinson’s and examining the long-term interaction between the body’s immune response to viral pathogens and brain health.
As the global population ages and the prevalence of Parkinson’s continues to rise, researchers hope these findings will clarify the mechanisms behind the disease and identify windows for early intervention. This work was supported by the National Institute for Neurological Disorders and Stroke and a Texas A&M College of Veterinary Medicine and Biomedical Sciences Graduate Trainee Grant.