Avian adeno-associated virus as an anterograde transsynaptic vector

Area of Science:

• Neuroscience
• Molecular Biology
• Virology

Background:

• Retrograde and anterograde transsynaptic viral vectors are crucial for mapping neuronal circuits.
• While retrograde vectors are common, efficient anterograde transsynaptic viral vectors are scarce.

Purpose of the Study:

• To develop and characterize a novel viral vector for anterograde transsynaptic tracing.
• To evaluate the efficacy of avian adeno-associated virus (A3V) in tracing neuronal connections.

Main Methods:

• Recombinant avian adeno-associated virus (A3V) carrying mCherry was injected into chicken eyes, cochleae, and auditory midbrain.
• Transcellular transport and mCherry expression were observed over various survival times.
• Co-injection with cholera toxin B subunit confirmed the transcellular transduction mode.

Main Results:

• A3V injections into the eye and cochlea labeled visual and auditory pathway neurons, respectively.
• Second- and third-order neuronal labeling occurred at 2 and 7 days post-injection in the midbrain.
• Labeled neuron distribution indicated preferential anterograde transport and transduction of postsynaptic neurons.

Conclusions:

• A3V exhibits no extrasynaptic leakage and a moderate synapse passage speed.
• A3V demonstrates superior anterograde transsynaptic tracing capabilities, spanning multiple synapses compared to AAV1&9.
• A3V is a promising tool for studying the topographic organization of projection axons and their targets.