Flavivirus prM interacts with MDA5 and MAVS to inhibit RLR antiviral signaling

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Vector-borne flaviviruses (TBEV, ZIKV, WNV, YFV, DENV, JEV) are a global health concern.
• These viruses possess sophisticated mechanisms to evade host antiviral innate immunity.
• The specific roles of flavivirus structural proteins in immune evasion are not fully understood.

Purpose of the Study:

• To investigate the mechanisms by which flavivirus structural proteins, particularly the pre-membrane (prM) protein, evade host immune responses.
• To elucidate the interaction of prM proteins with key components of the antiviral signaling pathway.

Main Methods:

• Investigated the interaction of tick-borne encephalitis virus (TBEV) prM protein with MDA5 and MAVS.
• Assessed the impact of prM protein interactions on the MDA5-MAVS complex formation and IRF3 activation.
• Examined prM proteins from other flaviviruses (ZIKV, WNV, DENV2, YFV, JEV) for similar interactions and effects on type I interferon (IFN-I) production.
• Studied the effect of TBEV and ZIKV prM overexpression on viral replication.

Main Results:

• TBEV prM protein inhibits type I interferon (IFN-I) production by interacting with MDA5 and MAVS, preventing MDA5-MAVS complex formation.
• This interaction disrupts IRF3 activation, hindering the RLR antiviral signaling pathway.
• ZIKV and WNV prM proteins also interact with MDA5 and MAVS, while DENV2 and YFV prM interact with only one of these proteins.
• Japanese encephalitis virus (JEV) prM does not suppress IFN-I production.
• Overexpression of TBEV and ZIKV prM enhances the replication of TBEV and Sendai virus.

Conclusions:

• Flavivirus prM proteins employ distinct strategies to suppress host IFN-I production.
• Understanding these immune evasion mechanisms is crucial for developing effective antiviral therapies and vaccines.
• The findings provide insights into flavivirus pathogenicity and host-pathogen interactions.