Alteration of interleukin-1 alpha production and interleukin-1 alpha binding sites in mouse brain during rabies infection.

We have evaluated the effect of rabies virus infection on interleukin-1 alpha (IL-1 alpha) production and its receptors in mouse brain. Study of virus dissemination in the central nervous system (CNS) showed a massive infection of main brain structures from day 4 post infection (p.i.) up to the agony stage on day 6 p.i. At the same time, IL-1 alpha concentrations increased in cortical and hippocampal homogenates, whereas no change was detected in serum. In non-infected mice, IL-1 alpha binding sites were observed in the dentate gyrus, the cortex, the choroid plexus, the meninges and the anterior pituitary. During rabies virus infection, a striking decrease in IL-1 alpha binding sites was observed on day 4 p.i. with a complete disappearance on day 6 p.i., except in the pituitary gland where they remained at control level. In conclusion, concomitantly with the early rabid pathological signs, brain IL-1 alpha production and IL-1 alpha binding sites are specifically and significantly altered by brain viral proliferation. These results indicate that IL-1 alpha could be involved in the brain response to viral infection as a mediator and could participate in the genesis of the rabies pathogeny.