Abstract

Background: Selecting the most efficient and specific adeno-associated virus (AAV) capsids for gene delivery to the nervous system via minimally invasive routes is critical to gene therapy advancement. While AAV9, rAAV2-retro, AAV-PHP.eB, and AAV-MacpnS1 have demonstrated significant central nervous system (CNS) transduction ability after systemic delivery, their tropism, efficiency, and safety profiles in a developmentally relevant model have yet to be systematically compared. This study comparatively evaluated four capsids after intravenous administration in neonatal C57BL/6 mice. Methods: Transgene expression was quantitatively assessed across multiple CNS regions, as well as in the heart and liver. Associated biochemical indicators of hepatic stress were also evaluated. Results: The resulting transduction profiles were distinct and capsid-specific. Both AAV9 and AAV-MacpnS1 induced widespread CNS transduction and robust peripheral organ expression. However, AAV-MacpnS1-neuronal tropism in the thalamus was superior, and it was also associated with the most prominent biochemical indicators of hepatic stress. In contrast, rAAV2-retro was remarkably specific to the medulla and spinal motor neurons, demonstrating a valuable safety profile. AAV-PHP.eB achieved broad cellular transduction in the spinal cord, but it was the least specific towards cholinergic motor neurons. Furthermore, transduction in DRG neurons using AAV9 and AAV-MacpnS1 was efficient, but that using rAAV2-retro or AAV-PHP.eB was not. Conclusions: These findings provide an “atlas-like” comparative framework that clearly outlines the strengths and limitations of each vector.