Infection with a recombinant vaccinia virus encoding myelin proteolipid protein causes suppression of chronic relapsing-remitting experimental allergic encephalomyelitis

Mice infected with a recombinant vaccinia virus (VVplp) encoding the myelin proteolipid protein (PLP) and then challenged with the encephalitogenic pe ptide, PLP139-151, developed a more severe acute attack vs, control mice. F ollowing this initial acute attack, vaccinated mice had significantly less clinical disease (relapses) than control vaccinated or mock vaccinated mice . Control mice developed a relapsing-remitting disease with severe clinical relapses. During the remission state in VVplp vaccinated mice, histopathol ogic changes were markedly reduced in the central nervous system (CNS) vs. control vaccinated or unvaccinated mice. Inflammation was mainly limited to the meninges with a reduction of mononuclear cells in the parenchyma of th e spinal cord in VVplp vaccinated and PLP139-151 challenged mice vs. contro l mice when inflammatory changes with demyelination was observed. During th e remission period an increase in IL-4 was seen. In addition, there was sig nificantly less T cell proliferation to PLP139-151 that was confirmed by an in vivo measurement of T cell reactivity, DTH responses. This suggests tha t the almost permanent remission state was dictated by a decreased responsi veness to PLP139-151 in VVplp vaccinated mice. (C) 1999 Elsevier Science B. V. All rights reserved.