A virus-induced molecular mimicry model of multiple sclerosis

Abstract

Molecular mimicry is the process by which virus infection activates T cells that are cross-reactive with self antigens.Infection of SJL/J mice with the neurotropic picornavirus Theiler's murine encephalomyelitis virus (TMEV) leads to a progressive CD4 + T cell-mediated demyelinating disease similar to multiple sclerosis.To study the potential of virus-induced molecular mimicry to initiate autoimmune demyelination, a nonpathogenic TMEV variant was engineered to encode a 30-mer peptide encompassing the immunodominant encephalitogenic myelin proteolipid protein (PLP139-151) epitope.Infection with the PLP139-151-encoding TMEV led within 10-14 days to a rapid-onset paralytic demyelinating disease characterized by PLP139-151-specific CD4 + Th1 responses; insertion of a nonself ovalbumin sequence led to restoration of the normal late-onset disease.Early-onset disease was also observed in mice infected with a TMEV encoding PLP139-151 with an amino acid substitution at the secondary T cell receptor (TCR) contact residue (H147A), but not in mice infected with TMEV encoding a PLP139-151 substitution at the primary TCR contact (W144A).Most significantly, mice infected with TMEV encoding a Haemophilus influenzae mimic peptide, sharing only 6 of 13 amino acids with PLP139-151, displayed rapid-onset disease and developed cross-reactive PLP139-151-specific CD4 + Th1 responses.To our knowledge, this is the first study showing that a naturally infectious virus encoding a myelin epitope mimic can directly initiate organ-specific T cell-mediated autoimmunity.