The role of sialic acid and Ca2+ ions in rabies virus-infected foxes brain

The receptors for rabies virus on the neuron membranes are polysialogangliosides arranged in multicomponent gelate structures. The impulse conductivity at the synapse membranes also depends on the interactions between negatively charged sialic acid from the oligosaccharide parts of gangliosides and positively charged Ca ions. From individual brain regions of healthy foxes and foxes naturally infected with rabies virus glycolipoprotein preparations were isolated. In them, the presence of polysialogangliosides and the concentration of sialic acid, Ca ions, and proteins were evidenced. The concentration of sialic acid was increased in all tested brain regions of the infected foxes. In the preparations from the cortex cerebri or cornu Ammonis of the infected foxes, 20-fold higher levels of sialic acid and the decreased concentrations of Ca ions were recorded. The increase in sialic acid levels is directly responsible for the augmented negative charge at synaptic membranes and, consequently, for a much higher permeability of these membranes, which results in a persistent stimulation followed by the release of neuro-transmitters.