Systemic AAV9 Gene Therapy: SMA Motor Neuron Rescue

A single intravenous infusion of AAV9 gene therapy — the mechanism behind the approved drug Zolgensma — has to run a gauntlet before it can help a child with spinal muscular atrophy: pre-existing antibodies can neutralize it in the bloodstream, the liver captures most of what survives, and only a fraction crosses the blood-brain barrier to actually transduce spinal motor neurons with a working SMN1 gene. This simulator renders that journey as an animated 3D particle system — circulating vector, hepatic sequestration, and BBB crossing into a spinal cord of motor neurons that light up as they're rescued — driven by a real dose-response model. Adjust the infused dose, the patient's age at treatment, and their pre-existing anti-AAV9 antibody titer to see how each one shifts the percentage of motor neurons transduced and the predicted motor-function outcome, illustrating why earlier treatment and antibody screening are central to how this therapy is actually used in the clinic.