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A new study offers compelling evidence supporting the long-held theory that viral infections can trigger the development of amyotrophic lateral sclerosis (ALS), a devastating motor neuron disease. Researchers at Texas A&M University have identified a specific mouse strain that exhibits ALS-like symptoms following a viral infection, potentially paving the way for new diagnostic tools and treatments.
Researchers have long suspected a link between viral infections and the onset of ALS, but proving a causal relationship has been challenging. This research, published in the Journal of Neuropathology & Experimental Neurology, provides the first animal model that strongly affirms this connection.
The team focused on the CC023 mouse strain, which demonstrated a remarkable response to Theiler’s murine encephalomyelitis virus (TMEV). “This is exciting because this is the first animal model that affirms the long-standing theory that a virus can trigger permanent neurological damage or disease—like ALS—long after the infection itself occurred,” explained a neurodegenerative disease expert with the Texas A&M University School of Public Health.
The study involved infecting five genetically diverse mouse strains with TMEV and meticulously tracking their responses across acute, subacute, and chronic phases of infection. Researchers employed five key methods: comparing spinal cord inflammation, assessing inflammation levels across strains, linking inflammation to physical symptoms, measuring viral load, and determining the correlation between viral load and spinal cord inflammation.
Key Findings Illuminate the Disease Process
The research yielded four critical insights into the progression of ALS-like symptoms:
- Early Nerve Damage: Within two weeks of infection, all mouse strains exhibited nerve damage in the lumbar spine, with some showing initial signs of illness as early as four days post-infection.
- Persistent Muscle Loss: While the virus was eventually eliminated from the spinal cord, the CC023 mice experienced lasting muscle wasting.
- Striking ALS Similarities: The CC023 mice developed physical symptoms and spinal lesions remarkably similar to those observed in human ALS patients.
- Immune Response Dynamics: The mice initially mounted a robust immune response to combat the virus, but this activity subsided once the virus was cleared.
In essence, the initial viral infection triggered an immune reaction, lesions, and early signs of illness in the lumbar spinal cord. Although the virus eventually disappeared, the resulting lesions and clinical symptoms persisted, particularly in the CC023 strain, mirroring the progression of ALS.
Genetics Play a Crucial Role
The study underscores the importance of genetic predisposition in determining susceptibility to viral-induced neurological damage. According to the research team, genetics matter significantly in how individuals respond to viral infections and whether they develop long-term neurological consequences.
“This study gives us a new way to understand the various types of damage caused by a viral infection to the spinal cord and its nerves and muscles, especially since we now know that the initial viral infection triggers lasting, damaging reaction in susceptible individuals,” the neurodegenerative disease expert stated.
The CC023 strain now serves as a valuable “test track” for identifying early biomarkers for ALS and developing targeted therapies, particularly for sporadic ALS, the most common form of the disease, which affects over 90% of patients and is not linked to inherited genetic mutations. .
This research was supported by grants from the National Institute for Neurological Disorders and Stroke, the National Institute for Environmental Health Sciences, and a National Science Foundation Graduate Research Fellowship.
Source: Texas A&M University
