A phosphomimetic-based mechanism of dengue virus to antagonize innate immunity

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• 14-3-3 proteins are crucial regulators of cellular processes, including immune responses.
• 14-3-3 epsilon (14-3-3ɛ) is vital for antiviral immunity, facilitating RIG-I translocation.
• RIG-I (Retinoic acid-inducible gene I) is a key pathogen sensor in innate immunity.

Purpose of the Study:

• To investigate the mechanism by which dengue virus (DV) antagonizes host antiviral immunity.
• To identify viral factors and host proteins involved in DV immune evasion.
• To explore the role of the 14-3-3ɛ protein in DV infection.

Main Methods:

• Co-immunoprecipitation assays to detect protein-protein interactions between DV NS3 and 14-3-3ɛ.
• Analysis of RIG-I translocation using cell-based assays.
• Generation and characterization of a recombinant DV mutant lacking the 14-3-3ɛ binding motif.
• Assessment of innate immune responses and T cell activation in infected hosts.

Main Results:

• The dengue virus NS3 protein directly binds to 14-3-3ɛ.
• A conserved phosphomimetic RxEP motif in NS3 is essential for 14-3-3ɛ binding.
• DV NS3 binding to 14-3-3ɛ inhibits RIG-I translocation to MAVS, blocking antiviral signaling.
• A recombinant DV mutant unable to bind 14-3-3ɛ exhibits impaired antagonism of RIG-I and elicits a stronger innate immune response.

Conclusions:

• Dengue virus employs a novel mechanism of antagonism by hijacking 14-3-3ɛ via a phosphomimetic motif in NS3.
• This interaction disrupts RIG-I-mediated antiviral signaling, contributing to viral immune evasion.
• Understanding this interaction provides insights for developing therapeutics targeting viral antagonism of host immunity.