TRAF6 Plays a Proviral Role in Tick-Borne Flavivirus Infection through Interaction with the NS3 Protease

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Tick-borne flaviviruses (TBFVs) cause severe neurological and hemorrhagic diseases.
• Understanding virus-host interactions is crucial for developing antiviral therapies.

Purpose of the Study:

• To identify virus-host interactions exploitable for therapeutic targets.
• To investigate the role of tumor necrosis factor receptor-associated factor 6 (TRAF6) in TBFV replication.

Main Methods:

• In silico analysis of the TBFV polyprotein for protein-binding motifs.
• Experimental validation of TBFV NS3 and TRAF6 interaction during infection.
• Site-directed mutagenesis of TRAF6-binding motifs (TBMs) in NS3.

Main Results:

• Two putative TRAF6-binding motifs (TBMs) were identified in the TBFV NS3 protein.
• TBFV NS3 directly interacts with TRAF6, which supports viral replication.
• Mutation of a key TBM in NS3 disrupted TRAF6 binding, reduced mature NS3 protease, and attenuated virus in vitro.
• This proviral role of TRAF6 was specific to TBFVs, not mosquito-borne flaviviruses.

Conclusions:

• Flaviviruses exploit innate immune factors like TRAF6 for replication.
• The TBFV NS3-TRAF6 interaction is a potential therapeutic target.
• Targeting this interaction may offer a strategy for treating TBFV infections.