Patick, Amy K.

Abstract Infection of certain strains of mice with Theiler’s murine encephalomyelitis virus results in persistence of virus and an immune-mediated primary demyelination in the central nervous system that resembles multiple sclerosis. Because susceptibility/resistance to demyelination in B10 congeneic mice maps strongly to class I MHC genes (D region) we tested whether expression of a human class I MHC gene (HLA-B27) would alter susceptibility to Theiler’s murine encephalomyelitis virus-induced demyelination. Transgenic HLA-B27 mice were found to co-express human and endogenous mouse class I MHC genes by flow microfluorimetry analysis of PBL. In the absence of the human transgene, H-2stf, or v mice but not H-2b mice had chronic demyelination and persistence of virus at 45 days after infection. No difference in degree of demyelination, meningeal inflammation, or virus persistence was seen between transgenic HLA-B27 and nontransgenic littermate mice of H-2f or H-2v haplotype. In contrast, H-2s (HLA-B27+) mice showed a dramatic decrease in extent of demyelination and number of virus-Ag+ cells in the spinal cord compared with H-2s (HLA-B27-) littermate mice. In addition, none of the eight H-2s mice homozygous for HLA-B27 gene had spinal cord lesions even though infectious virus was isolated chronically from their central nervous system. Expression of HLA-B27 transgene did not interfere with the resistance to demyelination normally observed in B10 (H-2b) mice. These experiments demonstrate that expression of a human class I MHC gene can modulate a virus-induced demyelinating disease process in the mouse.

Abstract Intracerebral infection of certain strains of mice with Theiler’s virus results in chronic immune-mediated demyelination in spinal cord. We used mouse mutants with deletion of the V beta class of TCR genes to examine the role of TCR genes in this demyelinating disease which is similar to multiple sclerosis. Quantitative analysis of spinal cord lesions demonstrated a markedly increased number and extent of demyelinated lesions in persistently infected RIII S/J mice which have a massive deletion of the TCR V beta-chain (V beta 5.2, V beta 8.3, V beta 5.1, V beta 8.2, V beta 5.3, V beta 8.1, V beta 13, V beta 12, V beta 11, V beta 9, V beta 6, V beta 15, V beta 17) compared with B10.RIII mice which are of identical MHC haplotype (H-2r) but have normal complement of V beta TCR genes. In contrast, infection of C57L (H-2b) or C57BR (H-2k) mice which have deletion of the V beta TCR genes (V beta 5.2, V beta 8.3, V beta 5.1, V beta 8.2, V beta 5.3, V beta 8.1, V beta 13, V beta 12, V beta 11, and V beta 9) resulted in few demyelinating lesions. Genetic segregation analysis of (B10.RIII x RIII S/J) x RIII S/J backcrossed mice and (B10.RIII x RIII S/J) F2 mice demonstrated correlation of increased susceptibility to demyelination with deletion of TCR V beta genes. The increase in number of demyelinating lesions correlated with increase in number of virus-Ag+ cells in spinal cord. These experiments provide strong evidence that the structural diversity at the TCR beta-complex can influence susceptibility to virus-induced demyelination.

ABSTRACTWild-type Daniel’s strain of Theiler’s virus (wt-DA) induces a chronic demyelination in susceptible mice which is similar to multiple sclerosis. A variant of wt-DA (designated DA-P12) generated during the 12th passage of persistent infection of a G26-20 glioma cell line failed to persist and induce demyelination in SJL/J mice. To identify the determinants responsible for this change in phenotype, we sequenced the capsid coding sequence (nucleotides [nt] 2991 to 3994) and found three mutations in VP1: residues 99 (Gly to Ser), 100 (Gly to Asp), and 103 (Asn to Lys). To study the role of these mutations in neurovirulence and demyelination, we prepared a recombinant virus, DAP-1C-2A/DA, with replacement of wt-DA nt 2991 to 3994 with the corresponding region of DA-P12, and viruses with individual point mutations at VP1 residues 99(Ser), 100(Asp), and 103(Lys). DAP-1C-2A/DA and viruses with a mutation at VP1 residue 99 or 100 (but not 103) completely attenuated the ability of wt-DA to induce demyelination. Failure to induce demyelination was not due to a general failure in growth, since DA-P12 and other mutant viruses lysed L-2 cells in vitro as effectively as wt-DA. The change in disease phenotype was independent of the specific B- or T-cell immune recognition because a decrease in the neurovirulence of mutant viruses was observed in neonatal mice and immune-deficient RAG1 −/− mice. This difference in neurovirulence is not the complete explanation for the failure of DA-P12 to demyelinate, since virus with a mutation at residue 103(Lys) had decreased neurovirulence but did induce demyelination. Therefore, point mutation at VP1 residue 99 or 100 altered the ability of wt-DA to demyelinate, perhaps related to a disruption in interaction between virus and receptor on certain neural cells.