Optimal AAV capsid/promoter combinations to target specific cell types in the common marmoset cerebral cortex

To achieve cell type-specific gene expression, using target cell-tropic AAV capsids is advantageous. However, their tropism across brain cell types remains unexplored in non-human primates. We assessed the tropism of nine AAV serotype capsids (AAV1, 2, 5, 6, 7, 8, 9, rh.10 (rh10), and DJ) on marmoset cerebral cortical cell types. Marmoset cerebral cortex was injected with different serotype AAVs expressing enhanced GFP (EGFP) by the ubiquitous chicken β-actin hybrid (CBh) promoter. After 4 weeks, all nine AAV capsid vectors, especially AAV9 and AAVrh10, caused highly neuron-selective EGFP expression. Some AAV capsids, including AAV5, caused EGFP expression in oligodendrocytes to a lesser extent, with minimal or no expression in astrocytes and microglia. Different ubiquitous CMV and CAG promoters showed similar neuron-predominant transduction. Conversely, all nine AAV capsid vectors with the astrocyte-specific hGFA(ABC1D) promoter selectively transduced astrocytes, except AAV5, which transduced oligodendrocytes modestly. Oligodendrocyte-specific mouse myeline basic protein (mMBP) promoter in AAV5 vectors transduced oligodendrocytes specifically and efficiently. Our results suggest optimal combinations of capsids and promoters for cell type-specific expression: AAV9 or AAVrh10 and ubiquitous CBh, CMV, or CAG promoter for neuron-specific transduction; AAV2 or 7 and hGFA(ABC1D) promoter for astrocyte-specific transduction; and AAV5 and mMBP promoter for oligodendrocyte-specific transduction. ### Competing Interest Statement The authors have declared no competing interest.