Immunoabsorbent nanoparticles based on a tobamovirus displaying protein A

Area of Science:

• * Virology
• * Protein Engineering
• * Nanobiotechnology

Background:

• * Previous efforts to display peptides longer than 20 amino acids (aa) on tobamovirus surfaces were unsuccessful.
• * Tobamoviruses, like tobacco mosaic virus, are plant viruses amenable to surface display engineering.

Purpose of the Study:

• * To engineer tobamovirus nanoparticles for displaying functional protein fragments.
• * To develop a cost-effective immunoadsorbent for monoclonal antibody (mAb) purification.

Main Methods:

• * A 133 aa functional fragment of protein A was genetically fused to the tobamovirus coat protein via a 15 aa linker.
• * The resulting engineered tobamovirus nanoparticles were expressed in plants and purified.
• * The nanoparticles were utilized as an immunoadsorbent for mAb purification.

Main Results:

• * A functional 133 aa protein A fragment was successfully displayed on tobamovirus nanoparticles.
• * A simple purification protocol yielded mAbs with 50% recovery and >90% purity.
• * Dense packing (>2,100 copies/particle) resulted in high binding capacity (2 g mAb/g).
• * High expression levels (>3 g adsorbent/kg biomass) indicate cost-effectiveness.

Conclusions:

• * Engineered tobamovirus nanoparticles serve as an effective platform for displaying large functional protein fragments.
• * This self-assembling matrix provides an inexpensive, high-capacity immunoadsorbent for industrial mAb purification.
• * The system demonstrates potential for single-use, large-scale antibody purification applications.