To generate the HD rat model, wild-type rats were injected intrastriatally with a LV expressing a chimeric mutant HTT fragment, which is shown to induce local formation of mutant HTT aggregates followed by severe neuronal dysfunction at two months post-infection.22 Therefore, this model allowed us to address the HD treatment response downstream of the mutant HTT protein in a larger rodent brain. The gene discussed is HTT; the disease is Huntington disease.