Effect of immunization with Theiler's virus on the course of demyelinating disease

Intracerebral (i.c.) inoculation of susceptible mice with Theiler's murine encephalomyelitis virus (TMEV) results in a demyelinating disease similar to human multiple sclerosis (MS). Mice develop a strong immune response to TMEV and the disease is believed to be immune-mediated. In order to investigate the effects of the immune response to TMEV on the course of demyelination, we immunized host mice with UV-inactivated TMEV at various time periods in relation to intracerebral inoculation with live TMEV. Here, we show that subcutaneous immunization of mice with TMEV prior to infection with virus is able to protect susceptible, SJL/J mice from demyelinating disease. This protective effect appears to be long-lasting; immunization greater than 90 days prior to i.c. inoculation of the virus protects mice from subsequent infection. However, immunization of mice after i.c. infection with TMEV does not confer protection, but rather exacerbates the disease symptoms. Thus, this system offers a model for studying viral capsid proteins and/or epitopes which are involved in either protection from disease or immune-mediated pathogenesis leading to myelin destruction in susceptible mice.