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

Abstract

Rabies encephalitis remains nearly 100% fatal once symptoms appear, and no effective treatments exist because the molecular mechanisms underlying neuronal disruption remain poorly understood. This has prevented the development of molecular-based therapies, leaving only symptomatic management strategies. RABV-G has long been proposed to interact with muscle and, more recently, neuronal nicotinic acetylcholine receptors (nAChRs), but neuronal receptors have only been implicated using short peptide fragments. This study characterizes the interaction of a synthetic full-length RABV-G ectodomain with two neuronal nAChR subtypes associated with rabies-related behaviors, α4β2 and α7. We examined two forms within the predicted nicotinic binding domain: the naturally occurring 183P variant and the charge-reversal substitution 196D, and tested whether modulation depends on the glycoprotein’s conformation by conducting experiments at pH 6.5 and 7.4. At physiological pH, 183P inhibited both receptors (approximate IC₅₀(α7) = 3.6–11.5 µM; approximate IC₅₀(α4β2) = 4.2–14.1 µM), whereas 196D produced potentiation (~60% for α4β2; 35–40% for α7). Co-application restored α4β2 currents to control levels. Modulation occurred only at pH 7.4. These findings show that full-length RABV-G directly modulates neuronal nAChRs, that residue 196 determines the modulation polarity, and that the pre-fusion conformation mediates this interaction, supporting the exploration of receptor-targeted strategies for rabies encephalitis.