Brain viral persistence and myelin damage in nude mice.

Multiple foci of secondary demyelination were observed in the cerebellum of nude mice given two inoculations of avirulent Semliki Forest virus compared to single lesions seen in similarly treated Swiss A2G mice. The increased number of demyelinative plaques were attributed to brain viral persistence for 35 days in the nude mice with correspondingly low serum antibody titres. No neurological signs were observed in any of the mice.