The TO strains of Theiler's viruses cause “slow virus—like” infections in mice

Abstract
Intracerebral inoculation of mice with tissue culture–adapted TO strains of Theiler's mouse encephalomyelitis viruses results in a clinical disease consisting of spastic paralysis due to demyelination after a lengthy incubation period. Thus, in effect, these ordinary picornaviruses are capable of causing a slow infection in their natural host, the mouse. In addition, through the use of tissue culture–adapted virus stocks, virus content in mouse tissues now can be accurately quantified by standard plaque assay.