Efficient entry of budded virions of Autographa californica multiple nucleopolyhedrovirus into Spodoptera frugiperda...

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an enveloped DNA virus in the Alphabaculovirus genus.
• AcMNPV budded virions (BVs) utilize clathrin-mediated endocytosis for host cell entry.
• The precise intracellular trafficking route of AcMNPV BVs post-entry remains unclear.

Purpose of the Study:

• To elucidate the intracellular trafficking pathway of AcMNPV budded virions (BVs) after cellular entry.
• To investigate the roles of specific Rab GTPases (Rab4, Rab5, Rab7, Rab11) in AcMNPV BV infection.
• To determine the endosomal compartments involved in AcMNPV BV de-envelopment.

Main Methods:

• Colocalization studies of AcMNPV BVs with cellular Rab proteins (Rab4, Rab5, Rab7, Rab11).
• Functional assays using dominant-negative (DN) Rab proteins and RNA interference (RNAi) to downregulate Rab expression.
• Inhibition assays using dynamin inhibitors (dynasore) and RNAi knockdowns of dynamin.

Main Results:

• Entering AcMNPV BVs colocalized primarily with Rab5 and Rab11, indicating association with early and recycling endosomes.
• Suppression of Rab5 and Rab11 significantly inhibited AcMNPV BV entry into Spodoptera frugiperda (Sf9) cells, but not viral egress.
• Rab4 and Rab7 had no significant impact on AcMNPV infection, and dynamin inhibition/knockdown also affected entry.

Conclusions:

• AcMNPV BVs enter host cells via clathrin-mediated endocytosis and are trafficked through early and maturing endosomes.
• The Rab5- and Rab11-dependent endosomal pathways are crucial for AcMNPV BV entry and de-envelopment.
• The Rab11-dependent recycling endosomal pathway is implicated in the virion entry process of AcMNPV.