Retrograde Mono-synaptic Tracing-Brain Case ()

Rabies Virus Retrograde Monosynaptic Tracing System: A useful tool for studying input circuits

The envelope glycoprotein (GP) of RV is essential for its retrograde transsynaptic transmission, with its receptors widely distributed at axon terminals. Upon infection, it can retrogradely enter neuronal cell bodies along axons to initiate virus replication. RV lacking the G protein (RV-ΔG) loses its transsynaptic capability, but its replication and transcription remain unaffected (allowing sustained high-level expression of exogenous genes). Therefore, RV-ΔG, when carrying reporter genes, functions similarly to CTB, retrobeads, etc., allowing for retrograde bright labeling of neurons with fine morphology. Additionally, complementing RV-G protein can assist RV-ΔG in retrograde transsynaptic infection of upstream neurons, thereby achieving transsynaptic neuronal network labeling.

The recombinant outer membrane protein (EnvA) fusion protein of avian sarcoma virus (ASLV) is used to package the virions formed by RV, which can specifically recognize the EnvA receptor TVA (TVA only exists in avian cells and is not found in mammalian neurons). Expression mediates the virus to specifically infect cells. By using Cre transgenic mice combined with Cre-LoxP to control the AAV helper virus that expresses TVA and G proteins, it is possible to express TVA and G proteins only in specific types of neurons in specific areas, thereby enabling retrograde monosynaptic tracing of specific neuronal types using RV-EnvA-ΔG. (Figure 1).

Figure 1. A: Principle of Retrograde Monosynaptic Tracing using RV, B: Schematic Diagram of Retrograde Monosynaptic Tracing using RV (ArenkielBR, et al., Nature.2009.)

Application

Studying specific brain areas and specific types of neurons in a retrograde monosynaptic input circuit (see case studies)

Case display

Example 1: Retrograde labeling of GABAergic neurons in hippocampal pyramidal neurons that simultaneously act on mPFC and ACB

• Experimental animals : Cre mice with inhibitory neurons (SST, PV, VIP)
• Viruses used : RV-EnvA-GFP, AAV-DIO-TVA-hBFP and AAV-DIO-RG
• Experimental methods and results : Inhibitory neuron (SST, PV, VIP) Cre mice injected with RV-EnvA-GFP in the mPFC brain region, along with Cre-dependent helper viruses AAV-DIO-TVA-hBFP and AAV-DIO-RG, achieved retrograde monosynaptic tracing. Simultaneously, in the ACB brain region, RV-DG-DsRed absorbed from axon terminals was injected to retrogradely label neurons projecting from the hippocampus to the ACB region, ultimately identifying GABAergic neurons that regulate both the mPFC and ACB areas in the hippocampus (see Figure 2).

Figure 2. Labeling of GABAergic neurons in hippocampal pyramidal neurons that act both in mPFC and ACB (Sunetal., Natureneuroscience, 2019)

Product List

-The CVS-N2c strain series of RV virus products, with lower toxicity and higher transsynaptic efficiency, is continuously being updated

If you are interested in the details of the experiment or the problems that may arise during the experiment and their causes, please contact: BD@ebraincase.com

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