Role of the glycoprotein thorns in anxious effects of rabies virus: Evidence from an animal study

Rabies is a lethal infectious disease caused by rabies virus (RABV). Fear and anxiety are the distinguished symptoms in rabies patients. Fusion of RABV envelope glycoprotein (RVG) to host cell membrane initiates rabies pathogenesis via interacting with PDZ domain of signaling proteins. We assessed the anxiety-like behaviors, and hypothalamic-pituitary-adrenal axis (HPA) response to RVG infection. Contribution of PDZ binding motif (PBM) of RVG to the observed effects was also examined using a mutant form of RVG, ΔRVG, with deleted last four amino acids at PBM C-terminus. Lentiviral vectors containing RVG and/or ΔRVG genes were injected into the rat brain areas involved in anxiety including hypothalamus, dorsal hippocampus, and amygdala. RVG/ΔRVG neural expression was examined by fluorescent microscopy. Anxiety-like behaviors were assessed by elevated plus maze (EPM) and open field (OF) tasks. HPA response was evaluated via measuring corticosterone serum level by ELISA technique. RVG/ΔRVG were successfully expressed in neurons of the injected areas. RVG, but not ΔRVG, infection of hypothalamus and amygdala increased the time spent in EPM open arms, and OF total distance moved and velocity. RVG, but not ΔRVG, infection of hypothalamus and dorsal hippocampus increased corticosterone level. The anxiety-like behaviors and exploratory/locomotor activities of rats with RVG infection in hypothalamus, and amygdala are mediated by PBM of RVG. The HPA response to RVG infection of hypothalamus and dorsal hippocampus is dependent to PBM of RVG. Triggering anxiety-related signaling by PBM of RVG seems to be one of the mechanisms involved in anxiety behaviors seen in patients with rabies.