The effect of neonatal thymectomy on Tamiami virus-induced central nervous system disease

Tamiami virus, a member of the arenavirus group, produces an acute CNS disease in suckling mice manifested primarily by cerebellar ataxia, paralysis, convulsions, and death. Animals that survive are left with an asymptomatic cerebellar heterotopia. Neonatal thymectomy prevents both acute CNS disease and the resultant cerebellar heterotopia despite equivalent titers of virus and concentrations of viral antigen in the brains of both thymectomized and nonthymectomized infected mice. Inflammatory CNS disease and cerebellar germinal cell necrosis do not develop in thymectomized mice examined more than three months after infection. Viremia and complement-fixing antibody occur in both groups of mice with slightly higher antibody titers in nonthymectomized mice. Tamiami virus-induced cerebellar heterotopia appears to be immunologically-mediated, but the immunopathologic cerebellar lesion differs from the frank necrosis of the brain produced by both Tacaribe and LCM virus in newborn mice.