Anterograde neuronal circuit tracing using a genetically modified herpes simplex virus expressing EGFP

Area of Science:

• Neuroscience
• Molecular Biology
• Virology

Background:

• Understanding neural circuits is crucial for neuroscience.
• Transynaptic viral tracing aids neuroanatomical studies.
• Existing viruses primarily trace retrograde neural connections.

Purpose of the Study:

• To construct a novel recombinant herpes simplex virus (HSV) for anterograde neural tracing.
• To characterize the replication and neuroinvasiveness of the new viral vector.
• To demonstrate its utility in mapping polysynaptic pathways.

Main Methods:

• Construction of an EGFP-expressing herpes simplex virus, strain H129 (HSV-1 H129-EGFP).
• In vitro and in vivo characterization of viral replication and neuroinvasiveness.
• Anterograde tracing by inoculating the upper airways and monitoring EGFP expression in sensory pathways.

Main Results:

• HSV-1 H129-EGFP demonstrated preferential anterograde movement along synaptically connected neurons.
• The virus retained replication and neuroinvasiveness comparable to wild-type H129.
• Time-dependent EGFP expression confirmed anterograde movement in polysynaptic ascending sensory pathways.

Conclusions:

• A genomic locus for recombining HSV-1 H129 was confirmed, maintaining viral function.
• HSV-1 H129-EGFP is a valuable tool for delineating central organization of peripheral sensory pathways.
• This novel viral vector facilitates studies of synaptic outputs from central neuronal populations.