Syn-GFP adenovirus

Adenoviruses are non-enveloped double-stranded DNA viruses with an icosahedral capsid, and due to their high transduction efficiency and rapid transgene expression, they have become a fundamental tool in molecular and systems neuroscience. Adenovirus type 5 (Ad5) is the most commonly used serotype in the laboratory, primarily entering cells via the coxsackievirus and adenovirus receptor (CAR) and integrin co-receptors. First-generation recombinant Ad5 vectors typically have the E1 region deleted (rendering the virus replication-deficient) and often also the E3 region (to increase cloning capacity and reduce host immunomodulation), allowing for safe production in complementary cell lines such as HEK293. These vectors exist as episomes and typically do not integrate into the host genome, providing potent and rapid transient expression—usually detectable within 24-72 hours and peaking within 1-2 weeks—making them ideal for acute experiments, pre-validation, and proof-of-concept studies.

The Syn-GFP adenovirus (Ad5 dE1/E3, expressing eGFP under the control of a synapsin promoter) utilizes a neuron-specific promoter to restrict transgene expression to neurons, providing a reliable and highly visible control for neuronal transduction studies. Because the synapsin (typically hSyn) promoter exhibits very low activity in glial cell populations such as astrocytes, microglia, and oligodendrocytes, Syn-GFP allows for precise verification of neuron specificity in dissociated cultures, organotypic slices, and in vivo brain regions. Typical applications include verifying stereotaxic targeting and diffusion, optimizing dosage and injection parameters, determining the time course of expression onset and peak, and establishing signal-to-noise ratio benchmarks for microscopy imaging workflows. The bright eGFP signal facilitates rapid assessment of neuronal morphology, axonal and dendritic labeling, and cell identification for subsequent electrophysiology or calcium imaging; it can also support FACS-based enrichment of transduced neurons for transcriptomic or proteomic analysis.