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Updated: Nov 22, 2025
High-throughput Quantitative Real-time RT-PCR Assay for Determining Expression Profiles of Types I and III Interferon Subtypes
Published on: March 24, 2015
Type I interferons are essential while type II interferon is dispensable for protection against St. Louis
Rebeca Froes Rocha1,2,3, Juliana L Del Sarto3, Giovanni F Gomes4
1Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM) , Campinas, Brazil.
Abstract:
St. Louis encephalitis virus (SLEV) is a neglected mosquito-borne flavivirus that causes severe neurological disease in humans. SLEV replication in the central nervous system (CNS) induces the local production of interferons (IFNs), which are attributed to host protection. The antiviral response to SLEV infection in the CNS is not completely understood, which led us to characterize the roles of IFNs using mouse models of St. Louis encephalitis. We infected mice deficient in type I IFN receptor (ABR-/-) or deficient in Type II IFN (IFNγ-/-) and assessed the contribution of each pathway to disease development. We found that type I and II IFNs play different roles in SLEV infection. Deficiency in type I IFN signaling was associated to an early and increased mortality, uncontrolled SLEV replication and impaired ISG expression, leading to increased proinflammatory cytokine production and brain pathology. Conversely, IFNγ-/- mice were moderately resistant to SLEV infection. IFNγ deficiency caused no changes to viral load or SLEV-induced encephalitis and did not change the expression of ISGs in the brain. We found that type I IFN is essential for the control of SLEV replication whereas type II IFN was not associated with protection in this model.
Insights
Type I interferons (IFNs) are crucial for controlling St. Louis encephalitis virus (SLEV) replication and preventing severe neurological disease. Type II IFNs do not appear to protect against SLEV infection in mouse models.
Area of Science:
- Virology
- Immunology
- Neuroscience
Background:
- St. Louis encephalitis virus (SLEV) is a significant cause of neurological disease transmitted by mosquitoes.
- The precise role of interferons (IFNs) in the central nervous system (CNS) during SLEV infection remains unclear.
- Understanding the host antiviral response is critical for developing effective treatments.
Purpose of the Study:
- To elucidate the distinct roles of type I and type II interferons (IFNs) in the host response to SLEV infection in the CNS.
- To investigate the impact of IFN signaling pathways on viral replication, disease progression, and neuropathology.
Main Methods:
- Utilized mouse models deficient in type I IFN receptor (ABR-/-) and type II IFN (IFNγ-/-).
- Infected mice with SLEV to assess mortality, viral load, and gene expression in the brain.
- Analyzed the expression of IFN-stimulated genes (ISGs) and proinflammatory cytokines.
Main Results:
- Mice lacking type I IFN signaling exhibited increased mortality, uncontrolled SLEV replication, and exacerbated brain pathology.
- Type I IFN deficiency led to impaired ISG expression and elevated proinflammatory cytokine production.
- Mice lacking type II IFN (IFNγ-/-) showed moderate resistance, with no significant changes in viral load or encephalitis severity.
Conclusions:
- Type I IFNs are essential for controlling SLEV replication and mitigating CNS disease.
- Type II IFNs do not play a protective role in this SLEV mouse model.
- These findings highlight the differential contributions of IFN pathways to flavivirus encephalitis.
