Effect of cyclosporin A on an experimental chronic viral infection of the central nervous system.

The effects of cyclosporin A (CsA) on neuropathological lesions induced by a chronic viral infection have been tested in the experimental model of the mouse hepatitis virus 3 (MHV3) infection. Daily injections of CsA (50 mg/kg) inhibited the expression of the MHV3-induced ependymitis, meningitis, hydrocephalus and vasculitis. The effect was preserved even if CsA treatment was initiated 15 days after virus infection but was lost if CsA treatment was given later on or for a shorter period of time. Viral titers in brains of chronically infected mice were not affected by CsA treatment. During the first week following MHV3 infection, CsA treatment increased both the percentage of acute death (31 vs. 10%) and the viral titers in brain and liver of infected mice. In this model, the timing of CsA treatment appeared critical for the balance between its beneficial effect on CNS lesions and the risk of increased acute mortality.