IFN-gamma production and astrocyte recognition by autoreactive T cells induced by Theiler's virus infection: role of viral strains and capsid proteins.

From mice infected with the DA strain of Theiler's murine encephalomyelitis virus (TMEV), CD8+ cytotoxic T lymphocytes (CTLs) could be detected after stimulation with TMEV infected antigen presenting cells (APCs). These CTLs killed not only TMEV infected but also uninfected syngeneic cells. Killing was associated with interferon (IFN)-gamma production in ELISPOT assays. The CTLs were efficiently induced by vaccinia virus encoding DA virus capsid proteins, but not by APCs infected with the GDVII strain of TMEV. The CTLs produced IFN-gamma in response to TMEV infected, but not uninfected, astrocytes. The CTLs could be maintained in the presence of interleukin (IL)-2. We hypothesized that, in DA virus infection, CD8+ CTLs specific for viral capsid protein could recognize self protein on oligodendrocytes by molecular mimicry, leading to demyelination.

Central nervous system pathology caused by autoreactive CD8+ T-cell clones following virus infection.

Theiler's murine encephalomyelitis virus (TMEV) causes a demyelinating disease in infected mice which has similarities to multiple sclerosis. Spleen cells from TMEV-infected SJL/J mice stimulated with antigen-presenting cells infected with TMEV resulted in a population of autoreactive CD8+ cytotoxic T cells that kill uninfected syngeneic cells. We established CD8+ T cell clones that could kill both TMEV-infected and uninfected syngeneic targets, although infected target cells were killed more efficiently. The CD8+ T-cell clones produced gamma interferon when incubated with either infected or uninfected syngeneic target cells. Intracerebral injection of the clones into naïve mice induced degeneration, not only in the brain, but also in the spinal cord. This suggests that CD8+ Tc1 cells could play a pathogenic role in central nervous system inflammation.