To utilize four viral tracer tools with different properties, to visualize cell morphology and connectome in visual pathways and explore and summarize the applications of different viral tracer tools in visual circuit, basing on the technology of neural circuitry tracing with viral vectors.
For cell tracing, C57BL/J mice were injected by fluorogold, adeno-associated virus (AAV), pseudorabies virus (PRV) or herpes simplex virus 1 strain 129 (H129). GAD2-Cre mice were injected by AAV.Thy1-Cre mice were injected by rabies virus (RV). Four mice were contained in every group.Retrograde tracing: mice were injected with fluorogold, AAV, PRV or RV in SC regions.After a certain period, their retinas were isolated, expanded into flat-mounted on slides to observe the morphology and distribution of labelled retinal cells.Anterograde tracing: mice were injected with H129 in vitreous cavities.After a certain period, their brains were isolated to observe the morphology and distribution of labelled brain cells.
The number of cells labelled by fluorogold was larger than that labelled by AAV.The morphology of cells labelled by AAV possessed more details than that by fluorogold.H129 and PRV injection could display numerous cells with synaptic connections in the visual circuit.Recombined RV could mono-transsynaptically spread and label cells with the support of helper virus.
AAV is more helpful in studying cell morphology.HSV-1, PRV and RV can be used to study cell connectomes.Cooperated with Cre/loxP system, Caspase-3, DTA, Gcamp or other neuroscience tools, viral tracer tools can be used to regulate the function of cells that belong to a specific cell type.