Japanese encephalitis virus hijacks ER-associated degradation regulators for its replication

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Flaviviruses, including Japanese encephalitis virus (JEV), replicate within the endoplasmic reticulum (ER).
• Viral and host proteins are essential for flavivirus replication complex formation and function.
• The ER-associated degradation (ERAD) pathway plays a role in protein homeostasis within the ER.

Purpose of the Study:

• To investigate the role of ER-associated degradation (ERAD) pathway proteins in Japanese encephalitis virus (JEV) replication.
• To determine the localization and functional significance of ERAD components during JEV infection.

Main Methods:

• High-resolution immunofluorescence imaging of JEV-infected HeLa cells.
• Analysis of viral protein (NS1, NS5) and ERAD protein colocalization.
• Transcriptional and protein level analysis of ERAD effectors.
• siRNA-mediated depletion of ERAD proteins (OS9, SEL1L, HERPUD1, HRD1).
• Viral RNA replication and titre quantification.
• Protein translation arrest experiments.

Main Results:

• JEV replication complexes (NS1) colocalized with ERAD proteins SEL1L, OS9, HERPUD1, HRD1, and DERLIN1.
• SEL1L also overlapped with NS5-positive structures.
• ERAD effector genes were transcriptionally upregulated, but protein levels remained stable.
• Depletion of OS9, SEL1L, HERPUD1, and HRD1 significantly reduced viral RNA replication and titres.
• SEL1L depletion caused the most substantial inhibition of JEV replication.
• SEL1L and OS9 protein levels were stabilized during JEV infection.

Conclusions:

• ERAD pathway proteins SEL1L, OS9, HERPUD1, and HRD1 are crucial host factors for JEV replication.
• These ERAD proteins are essential for efficient viral RNA synthesis and production.
• JEV infection influences the stability and function of specific ERAD components.