A mosaic adeno-associated virus vector as a versatile tool that exhibits high levels of transgene expression and neuron specificity in primate brain

Abstract

Recent emphasis has been placed on gene transduction mediated through recombinant adeno-associated virus (AAV) vector to manipulate activity of neurons and their circuitry in the primate brain. In the present study, we created a novel vector of which capsid was composed of capsid proteins derived from both of the AAV serotypes 1 and 2 (AAV1 and AAV2). Following the injection into the frontal cortex of macaque monkeys, this mosaic vector, termed AAV2.1 vector, was found to exhibit the excellence in transgene expression (for AAV1 vector) and neuron specificity (for AAV2 vector) simultaneously. To explore its applicability to chemogenetic manipulation and in vivo calcium imaging, the AAV2.1 vector expressing excitatory DREADDs or GCaMP was injected into the striatum or the visual cortex of macaque monkeys, respectively. Our results have defined that such vectors secure intense and stable expression of the target proteins and yield conspicuous modulation and imaging of neuronal activity.

Multimodal Imaging for Validation and Optimization of Ion Channel-Based Chemogenetics in Nonhuman Primates

“…We have previously tested the DREADD excitability of striatal neurons in combination with hM3Dq and DCZ using FDG uptake as a marker and found that 1 µg/kg of DCZ increased striatal uptake by ∼10% ( Nagai et al, 2020 ; Kimura et al, 2023 ), a similar range to what we observed for PSAM4 requiring a 100-fold higher dose of PSEM in the current study. Assuming comparable expression levels because the same AAV vector was used at similar titers in these cases, DREADD/DCZ may have greater efficacy in activating striatal neurons, although generalization by direct comparison is still limited.…”

“…In the current study, we used AAV2.1 vectors with a human synapsin promoter (hSyn) for neuron-specific transduction of PSAM4-5HT3 with or without fusion protein tags. The combination of AAV2.1, hSyn, and HA/FLAG tags has been used in this study and in previous hM4Di/hM3Dq DREADD studies with macaque monkeys ( Kimura et al, 2023 ; Miyakawa et al, 2023 ). As expected, our AAV construct successfully induced PSAM4-5HT3 expression in the striatum and MI cortex, as visualized by [ 18 F]ASEM-PET.…”

“…Viral titer was determined by quantitative PCR using Taq-Man technology (Life Technologies). Additional details have been described previously ( Kimura et al, 2023 ). cDNA fragments encoding PSAM4, such as PSAM4-5HT3, were synthesized based on the sequences originally reported by Magnus et al (2019) .…”