Resolving the APN controversy in PEDV infection: Comparative kinetic characterization through single-virus tracking

Area of Science:

• Virology
• Cell Biology
• Biochemistry

Background:

• Aminopeptidase N (APN) functions as a viral receptor for several coronaviruses.
• The precise role of porcine APN (pAPN) in porcine epidemic diarrhea virus (PEDV) entry has been debated.
• Understanding receptor dynamics is crucial for viral infection mechanisms.

Purpose of the Study:

• To quantitatively analyze the role of pAPN in the entry of PEDV, TGEV, and SADS-CoV.
• To elucidate the dynamic differences in pAPN-mediated viral internalization.
• To resolve controversies regarding pAPN's function in PEDV infection.

Main Methods:

• Molecular docking and surface plasmon resonance (SPR) to assess pAPN-virus binding affinity.
• Single-virus tracking to dynamically observe and quantify viral internalization processes.
• Comparative analysis of PEDV, TGEV, SADS-CoV, and PDCoV internalization via pAPN.

Main Results:

• pAPN binds to PEDV with lower affinity than to TGEV.
• pAPN facilitates PEDV internalization via clathrin- and caveolae-mediated endocytosis in susceptible cells.
• pAPN mediates 35% of PEDV internalization events, occurring ~60s slower than TGEV, with similar movement durations but delayed binding.
• Porcine deltacoronavirus (PDCoV) internalization dynamics via pAPN resemble those of TGEV.

Conclusions:

• pAPN's role in PEDV entry is confirmed, clarifying previous controversies.
• Significant dynamic differences exist in pAPN-mediated internalization among coronaviruses (PEDV, TGEV, PDCoV, SADS-CoV).
• Kinetic analysis provides a novel basis for evaluating viral receptors and developing intervention strategies.