Chimeric hepatitis B virus core particles as probes for studying peptide-integrin interactions

Area of Science:

• Virology
• Immunology
• Biotechnology

Background:

• Hepatitis B virus core (HBc) protein self-assembles into virus-like particles (VLPs).
• Foot-and-mouth disease virus (FMDV) utilizes specific cell surface receptors for entry.
• Engineering VLPs for displaying foreign epitopes is a promising vaccine and research strategy.

Purpose of the Study:

• To create a chimeric HBc-FMDV VP1 protein displaying an RGD-containing epitope.
• To investigate the binding properties and receptor interactions of these novel chimeric particles.
• To establish HBc VLPs as a versatile platform for studying peptide-receptor interactions.

Main Methods:

• Insertion of an RGD-containing epitope from FMDV VP1 into the HBc e1 loop.
• Expression and purification of chimeric HBc-FMDV VLPs in Escherichia coli.
• Immunization of guinea pigs and assessment of antibody responses (ELISA, virus neutralization).
• Cell binding assays using cultured eukaryotic cells and purified integrins.
• Mutational analysis (RGE substitution) and competitive binding assays.

Main Results:

• High-level expression and spontaneous assembly of chimeric HBc-FMDV VLPs.
• Fusion particles elicited significant FMDV-neutralizing and ELISA antibody responses.
• Chimeric particles demonstrated specific binding to eukaryotic cells and purified integrins.
• The RGD sequence was critical for particle binding, implicating α5β1 integrin as a receptor.
• Chimeric particles competed with FMDV for binding to susceptible cells.

Conclusions:

• Engineered HBc VLPs displaying FMDV epitopes are immunogenic and can be readily produced.
• The RGD motif on chimeric particles mediates binding to α5β1 integrins, similar to FMDV.
• HBc VLPs offer a valuable and generalizable system for studying peptide-epitope interactions with cellular receptors.