Association of L* protein of Theiler's murine encephalomyelitis virus with microtubules in infected cells.

We used an antibody raised against a synthetic peptide corresponding to amino acid residues 70-88 for characterizing the L* protein of Theiler's murine encephalomyelitis virus (TMEV), which is only synthesized in DA subgroup strains from an alternative AUG and is out of frame with the viral polyprotein; evidence suggests that L* protein is critical to viral persistence, demyelination, and growth in murine macrophage cell lines. It was synthesized with kinetics similar to that of other viral proteins, although less in amount. After synthesis, it remained stable in the cytoplasm and was not incorporated into virions. Immunofluorescent staining and immunoblotting of microtubule preparations demonstrated that it is associated with microtubules. Expression of L* protein also demonstrated that the 5' one third of the coding region may be responsible for the association. The association of L* protein with microtubules may be important in the disease-inducing and in vitro characters of L* protein.