A Plant Virus Glycoprotein Induces Autophagy by Activating the Toll7 Immune Pathway in Its Insect Vector

Area of Science:

• Insects
• Virology
• Immunology

Background:

• The Toll7 pathway is vital for innate immunity against pathogens.
• Plant viruses rely on insect vectors for transmission and replication.

Purpose of the Study:

• To investigate the role of Toll7 in antiviral defense against rice stripe virus (RSV) in the insect vector Laodelphax striatellus.
• To elucidate the molecular mechanism by which Toll7 mediates antiviral immunity.

Main Methods:

• Identified interaction between Toll7 TIR domain and RSV glycoprotein (Gc).
• Utilized Toll7 silencing and PI3K-Akt-mTOR pathway gene silencing.
• Performed transcriptomic analysis to study pathway regulation and autophagy.
• Assessed RSV replication and acquisition in insect vectors.

Main Results:

• Toll7 silencing enhanced RSV replication and acquisition in L. striatellus.
• Toll7 negatively regulates the PI3K-Akt-mTOR pathway, a key autophagy regulator.
• Toll7 knockdown led to upregulation of PI3K, Akt, mTOR, and downregulation of autophagy-related genes.
• Silencing PI3K, Akt, or mTOR suppressed RSV replication, confirming their role in viral persistence.

Conclusions:

• Toll7 inhibits the PI3K-Akt-mTOR pathway, thereby activating autophagy to restrict RSV replication in L. striatellus.
• This study reveals a conserved Toll7-dependent antiviral mechanism involving autophagy.
• Findings provide insights into plant virus-insect vector co-evolutionary dynamics.