Viral infection triggers ALS-like disease in mice with specific genes
Viruses can leave behind permanent neurological damage, study says
- Viral infection can trigger ALS-like disease in genetically susceptible mice.
- Damage to the spinal cord and muscles persists even after the virus clears.
- This mouse model offers a platform for identifying biomarkers and testing ALS therapies.
A viral infection can trigger a neurological disease similar to amyotrophic lateral sclerosis (ALS) in mice with a specific genetic profile, providing evidence for how genetics and environment may interact to cause the disorder, according to a new study.
Findings suggest that while a virus may be the initial spark, the resulting damage to the spinal cord and muscles can persist in susceptible individuals even after the infection has cleared. This triggering mechanism helps explain why identifying environmental triggers in ALS patients is so difficult, as the original virus may no longer be present by the time symptoms appear.
“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,” Candice Brinkmeyer-Langford, PhD, a co-author of the study at the Texas A&M University School of Public Health, said in a university news story.
The study, “The association between virus-induced spinal cord pathology and the genetic background of the host,” was published in the Journal of Neuropathology & Experimental Neurology.
A new model for environmental triggers
ALS is a neurological disease marked by the death and degeneration of motor neurons, the nerve cells that control movement. The causes of ALS remain incompletely understood. Genetics are known to play a key role, but environmental exposures such as infections may also influence disease development.
In this study, scientists were working to understand how different genetic backgrounds in mice affect responses to a viral infection. They infected five different strains of mice with the same virus, then conducted detailed analyses to compare patterns of tissue damage and clinical outcomes.
The specific virus used, called Theiler’s murine encephalomyelitis virus (TMEV), infects mice and mainly affects the spinal cord. Even though all mice developed some degree of spinal cord damage following TMEV infection, the patterns of damage varied markedly across strains.
“We demonstrated that host genetic background significantly influences the damage to the spinal cord … associated with TMEV infection and the associated clinical signs,” the researchers wrote.
The team said their findings suggest that genetic differences can strongly influence how the nervous system responds to viral infection. This means that results from laboratory studies may depend heavily on the genetic makeup of the animals being used, and scientists studying how viral infections contribute to neurological disease will need to take this into account.
In their analyses, the scientists noticed that one of the mouse strains, dubbed CC023, developed a neurological disease similar to ALS following TMEV infection. These mice experienced muscle weakness and shrinkage similar to what’s seen in ALS patients, and these neurological problems persisted even after the virus was no longer detectable in the mice’s bodies.
“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,” Brinkmeyer-Langford said.
The scientists suggested that further experiments using this mouse strain “may provide a unique platform for identifying biomarkers and testing novel therapies” for ALS.
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