The Regulatory role of Interferon-induced protein with tetratricopeptide repeat 2 (Ifit2) in murine-β-coronavirus induced neuroinflammatory demyelination

Sharma, Madhav (2025) The Regulatory role of Interferon-induced protein with tetratricopeptide repeat 2 (Ifit2) in murine-β-coronavirus induced neuroinflammatory demyelination. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Madhav Sharma (17IP006)) 17IP006.pdf - Submitted Version Restricted to Repository staff only Download (13MB)

Abstract

Interferons (IFNs) protect against viral dissemination and pathogenesis by inducing the expression of interferon-stimulated genes (ISGs). Among these ISGs, Ifit2 plays a critical antiviral role, though its precise molecular mechanisms remain poorly understood. Using an Ifit2⁻/⁻ mouse model, this study demonstrated that intracranial inoculation of RSA59 resulted in uncontrolled viral replication, reduced microglial activation, and impaired T-cell recruitment during the acute neuroinflammation phase within the CNS. RSA59 infection in Ifit2 deficient mice reduced CD4⁺ T cell activation in cervical lymph nodes and limited blood-brain barrier permeability, evidenced by preserved tight junction protein, claudin-5, and adaptor protein ZO-1 expression. The impaired acute neuroinflammation in the absence of Ifit2 resulted in viral persistence and exacerbated chronic demyelination. Further investigations, using a reductionist approach, revealed that wild-type primary astrocytes exhibited robust Ifit2 upregulation and syncytia formation upon RSA59 infection. However, viral replication in Ifit2⁻/⁻ primary astrocytes increased significantly, accompanied by reduced mRNA expression of cytokines, transcription factors NF-κB and IRF3, and diminished oxidative stress responses. Co-immunoprecipitation assays indicated a potential interaction between Ifit2 and the viral nucleocapsid protein, highlighting Ifit2’s direct antiviral role. This study further established a protocol for isolating and characterizing major neuroglial cells in culture, including astrocytes, hippocampal neurons, oligodendrocyte precursor cells (OPCs), and microglia, from neonatal pup brains. RSA59 infection in these murine primary cells differentially induced Ifit2 expression, with astrocytes, neurons, and OPCs upregulating Ifit2, while microglia did not upregulate Ifit2 expression. This study provides critical insights into the cellular mechanisms underlying Ifit2-mediated antiviral immunity and its regulation of neuroglial cells. By limiting viral replication, modulating immune responses, and controlling neuroinflammation, Ifit2 emerges as a key factor in mitigating acute viral neuropathogenesis and chronic demyelination. These findings highlight Ifit2's potential as a promising therapeutic target for managing CNS viral infections and their long-term consequences.

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