Structural and functional basis of VLDLR usage by Eastern equine encephalitis virus.

Area of Science:

• Virology
• Structural Biology
• Immunology

Background:

• The very-low-density lipoprotein receptor (VLDLR) has eight LDLR type A (LA) domains.
• VLDLR facilitates the entry of alphaviruses like Eastern equine encephalitis virus (EEEV) and Semliki Forest virus (SFV).

Purpose of the Study:

• To elucidate the structural basis of EEEV interaction with VLDLR.
• To investigate the functional significance of these interactions in viral entry and infection.
• To develop a VLDLR-based therapeutic strategy against EEEV.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to resolve EEEV-VLDLR complexes.
• Site-directed mutagenesis and functional assays to assess binding and infection.
• In vivo studies in mice to evaluate therapeutic efficacy.

Main Results:

• EEEV engages multiple VLDLR LA domains simultaneously via distinct sites (E1/E2 cleft and E2 A domain).
• No single LA domain is essential or sufficient for EEEV infection, indicating complex binding.
• Specific EEEV strains exhibit an additional VLDLR binding site on the E2 B domain due to an amino acid substitution.
• A minimal VLDLR decoy receptor was designed, demonstrating neutralization of EEEV and protection in a mouse model.

Conclusions:

• EEEV employs a multi-site binding strategy to utilize VLDLR for viral entry.
• VLDLR binding is complex, involving simultaneous engagement of multiple domains.
• Targeting VLDLR interaction sites offers a promising therapeutic avenue for EEEV.
• A VLDLR decoy receptor represents a potential intervention for EEEV infection.