Rabies virus glycoprotein variants modulate neuronal nicotinic receptors in a conformation-dependent manner

Area of Science:

• Neurovirology
• Molecular Neuroscience
• Receptor Pharmacology

Background:

• Rabies encephalitis is almost invariably fatal post-symptom onset due to poorly understood neuronal disruption mechanisms.
• Existing treatments are limited to symptom management, hindering the development of molecular-based therapies.
• Previous research suggested interactions between Rabies Virus Glycoprotein (RABV-G) and nicotinic acetylcholine receptors (nAChRs), but primarily using peptide fragments.

Purpose of the Study:

• To characterize the interaction of the full-length RABV-G ectodomain with neuronal nAChR subtypes α4β2 and α7.
• To investigate the role of specific RABV-G variants (183P and 196D) and glycoprotein conformation (pH 6.5 vs. 7.4) in receptor modulation.
• To explore the potential for receptor-targeted strategies against rabies encephalitis.

Main Methods:

• Electrophysiological characterization of synthetic full-length RABV-G ectodomain interactions with α4β2 and α7 nAChRs.
• Assessment of two RABV-G variants (183P and 196D) within the predicted nicotinic binding domain.
• Experiments conducted at physiological (pH 7.4) and acidic (pH 6.5) conditions to evaluate conformational effects.

Main Results:

• At physiological pH 7.4, the 183P variant of RABV-G inhibited both α7 and α4β2 nAChRs.
• The 196D variant of RABV-G potentiated α4β2 (approx. 60%) and α7 (35-40%) nAChR activity at pH 7.4.
• Co-application of variants restored α4β2 currents to control levels, and modulation was pH-dependent, occurring only at pH 7.4.

Conclusions:

• Full-length RABV-G directly modulates neuronal nAChR subtypes α4β2 and α7.
• Residue 196 is critical in determining the polarity of receptor modulation (inhibition vs. potentiation).
• The pre-fusion conformation of RABV-G mediates this interaction, supporting the development of nAChR-targeted rabies therapies.