The immunodominant CD8+ T cell epitope region of Theiler's virus in resistant C57BL/6 mice is critical for anti-viral immune responses, viral persistence, and binding to the host cells

Abstract

Theiler's virus infection induces an immune-mediated demyelinating disease, providing a relevant animal model of human multiple sclerosis. VP2(121-130)-specific CD8+ T cells in resistant H-2b mice account for the majority of CNS-infiltrating CD8+ T cells. To further study the role of the CD8(+) T cells, we generated a panel of mutant viruses substituted with L, G, or T at the anchor residue (M130) of the VP2(121-130) epitope. M130L virus (M130L-V) with a substitution of M with L displayed similar properties as wild-type virus (WT-V). However, M130G-V and M130T-V could not establish a persistent infection in the CNS. The level of both virus-specific CD8+ and CD4+ T cell responses is significantly reduced in mice infected with these variant viruses. While all mutant and wild-type viruses replicate comparably in BHK cells, replication of M130G-V and M130T-V in macrophages was significantly lower compared to those infected with WT-V and M130L-V. Interestingly, these mutant viruses deficient in replication in primary mouse cells showed drastically reduced binding ability to the cells. These results suggest that the anchor residue of the predominant CD8+ T cell epitope of TMEV in resistant mice is critical for the virus to infect target cells and this deficiency may result in poor viral persistence leading to correspondingly low T cell responses in the periphery and CNS. Thus, selection of the cellular binding region of the virus as the predominant epitope for CD8+ T cells in resistant mice may provide a distinct advantage in controlling viral persistence by preventing escape mutations.

Alteration of encephalomyocarditis virus pathogenicity due to a mutation at position 100 of VP1

“…It seems that the BJC3 strain has poor myocardial proliferation, similar to some previously reported EMCV isolates [3]. The discrepancy between in vivo and in vitro kinetics might be related to the different virus receptor(s) on BHK-21 cells and mice target cells, as suggested previously with TMEV variants [21]. Further histological analyses demonstrated an obvious correlation between damage in target organs, overall in vivo replication, and certain strain-dependent properties.…”

Predominant Clonal Accumulation of CD8+T Cells with Moderate Avidity in the Central Nervous Systems of Theiler's Virus-Infected C57BL/6 Mice

“…All synthetic peptides purified by high-performance liquid chromatography to Ͼ95% purity were obtained from Genemed Synthesis, San Francisco, CA. These include the TMEV VP2 121-130 (FHAGSLLVFM) (6,13) and VP2 M130L (FHAGSLLVFL) peptides (41).…”

“…The generation of mutant viruses was previously described (41). Briefly, viral RNA was transcribed in vitro from a full-length WT (pSBW) or mutant (pSBW-VP2 M130L ) viral plasmid using T7 RNA polymerase in the presence of RNasin (Promega, Madison, WI).…”

“…Therefore, clonal expansion of certain CD8 ϩ T cells may be associated with the pathogenesis of demyelinating diseases. However, B6 mice, which are resistant to TMEV-induced demyelinating disease, induce strong CD8 ϩ T-cell responses to a single predominant epitope (VP2 121-130 ), i.e., Ն70% of CNSinfiltrating CD8 ϩ T cells (41,42). These CD8 ϩ T cells result in effective viral clearance yet remain at a low level in the CNS more than 120 days postinfection (dpi) without detectable pathology (42).…”

“…Among these models, the detailed T-cell V␤ repertoire in the CNS was described only in the MHV model (46). CD8 ϩ T-cell responses against TMEV in B6 mice are primarily against a single predominant epitope (22,36,41). However, virtually no study of the TCR V␤ repertoires of virus-specific CD8 ϩ T cells has been reported.…”