To date, a therapy for Huntington's disease (HD), a genetic, neurodegenerative disorder, remains elusive. HD is characterized by cell loss in the basal ganglia, with particular damage to the putamen, an area of the brain responsible for initiating and refining motor movements. Consequently, patients exhibit a hyperkinetic movement disorder. RNA interference (RNAi) offers therapeutic potential for this disorder by reducing the expression of HTT, the disease-causing gene. We have previously demonstrated that partial suppression of both wild-type and mutant HTT in the striatum prevents behavioral and neuropathological abnormalities in rodent models of HD. However, given the role of HTT in various cellular processes, it remains unknown whether a partial suppression of both alleles will be safe in mammals whose neurophysiology, basal ganglia anatomy, and behavioral repertoire more closely resembles that of a human. Here, we investigate whether a partial reduction of HTT in the normal non-human primate putamen is safe. We demonstrate that a 45% reduction of rhesus HTT expression in the mid- and caudal putamen does not induce motor deficits, neuronal degeneration, astrogliosis, or an immune response. Together, these data suggest that partial suppression of wild-type HTT expression is well tolerated in the primate putamen and further supports RNAi as a therapy for HD.

Key Points IL-15 superagonist sends antiviral CD8 T cells to B-cell follicles, which typically exclude them.

Aging is usually accompanied by diminished immune protection upon infection or vaccination. While aging results in well-characterized changes in the T-cell compartment of long-lived, outbred, and pathogen-exposed organisms, their relevance for primary antigen responses remain unclear. Therefore, it remains unclear whether and to what extent the loss of naïve T-cells, their partial replacement by oligoclonal memory populations, and the consequent constriction of T-cell receptor (TCR) repertoire, limit the antigen responses in aging primates.