Browsing by Author "Valbon, Stefanie F."

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    Cyclophilin D Regulates Antiviral CD8+ T Cell Survival in a Cell-Extrinsic Manner
    (AAI, 2020-04) Condotta, Stephanie A.; Downey, Jeffrey; Pardy, Ryan D.; Valbon, Stefanie F.; Tarrab, Esther; Lamarre, Alain; Divangahi, Maziar; Richer, Martin J.; Microbiology and Immunology, School of Medicine
    CD8+ T cell–mediated immunity is critical for host defense against viruses and requires mitochondria-mediated type I IFN (IFN-I) signaling for optimal protection. Cyclophilin D (CypD) is a mitochondrial matrix protein that modulates the mitochondrial permeability transition pore, but its role in IFN-I signaling and CD8+ T cell responses to viral infection has not been previously explored. In this study, we demonstrate that CypD plays a critical extrinsic role in the survival of Ag-specific CD8+ T cell following acute viral infection with lymphocytic choriomeningitis virus in mice. CypD deficiency resulted in reduced IFN-I and increased CD8+ T cell death, resulting in a reduced antiviral CD8+ T cell response. In addition, CypD deficiency was associated with an increase in pathogen burden at an early time-point following infection. Furthermore, our data demonstrate that transfer of wild-type macrophages (expressing CypD) to CypD-deficient mice can partially restore CD8+ T cell responses. These results establish that CypD plays an extrinsic role in regulating optimal effector CD8+ T cell responses to viral infection. Furthermore, this suggests that, under certain circumstances, inhibition of CypD function may have a detrimental impact on the host’s ability to respond to viral infection.
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    An epidemic Zika virus isolate suppresses antiviral immunity by disrupting antigen presentation pathways
    (Springer Nature, 2021-06-30) Pardy, Ryan D.; Valbon, Stefanie F.; Cordeiro, Brendan; Krawczyk, Connie M.; Richer, Martin J.; Microbiology and Immunology, School of Medicine
    Zika virus (ZIKV) has emerged as an important global health threat, with the recently acquired capacity to cause severe neurological symptoms and to persist within host tissues. We previously demonstrated that an early Asian lineage ZIKV isolate induces a highly activated CD8 T cell response specific for an immunodominant epitope in the ZIKV envelope protein in wild-type mice. Here we show that a contemporary ZIKV isolate from the Brazilian outbreak severely limits CD8 T cell immunity in mice and blocks generation of the immunodominant CD8 T cell response. This is associated with a more sustained infection that is cleared between 7- and 14-days post-infection. Mechanistically, we demonstrate that infection with the Brazilian ZIKV isolate reduces the cross-presentation capacity of dendritic cells and fails to fully activate the immunoproteasome. Thus, our study provides an isolate-specific mechanism of host immune evasion by one Brazilian ZIKV isolate, which differs from the early Asian lineage isolate and provides potential insight into viral persistence associated with recent ZIKV outbreaks.