Acute viral infection accelerates neurodegeneration in a mouse model of ALS

Abstract

While several viral infections have been associated with amyotrophic lateral sclerosis (ALS), the mechanism(s) through which they promote disease remains elusive. Here we investigate the impact of common, acute viral infections on ALS disease onset and progression in the SOD1G93A mouse model. A single sublethal infection prior to onset of ALS clinical signs is associated with markedly accelerated ALS disease progression characterized by rapid loss of hindlimb function. Prior infection results in gliosis in the lumbar spine and upregulation of transcriptional pathways involved in inflammatory responses, metabolic dysregulation, and muscular dysfunction. Therapeutic suppression of gliosis with an anti-inflammatory small molecule, or administration of a direct-acting antiviral, is associated with significantly improved ALS clinical signs, akin to what is observed in uninfected animals. Our study provides causal and mechanistic evidence that the immune response elicited by acute viral infections may be an important etiological factor that alters ALS disease trajectory. Common, acute, non-neurotropic respiratory virus infections accelerate ALS disease progression well after the virus has been cleared by augmenting inflammation of glial cells in the spinal cord and motor neuron loss. Anti-inflammatory and antiviral treatment delay disease progression, pointing to infection as a modifiable ALS risk factor.