Low immunogenic bio-nanocapsule based on hepatitis B virus escape mutants

Area of Science:

• Biotechnology
• Nanomedicine
• Hepatology

Background:

• Bio-nanocapsules (BNCs) derived from hepatitis B virus surface antigen (HBsAg) L proteins are effective non-viral vectors for liver-targeted gene and drug delivery.
• Endogenous anti-HBsAg immunoglobulins (HBIGs) in hepatitis B (HB) vaccinees and patients can impede BNC efficacy and limit repeated administration.
• Reducing the immunogenicity of BNCs is crucial for expanding their clinical applications in liver-targeted therapies.

Purpose of the Study:

• To engineer low-immunogenic BNCs capable of evading pre-existing anti-HBsAg antibodies.
• To evaluate the reduced immunogenicity and enhanced delivery efficacy of engineered BNCs in the presence of HBIGs.
• To expand the therapeutic potential of BNC-based nanomedicine for liver-specific applications.

Main Methods:

• Generation of escape mutant-type BNCs (emBNCs) by introducing two point mutations into the HBsAg L protein, mimicking HBV escape mutants.
• Assessment of HBIG binding capacity and immunogenicity of emBNCs compared to wild-type BNCs (wtBNCs) in vitro and in BALB/c mice.
• Evaluation of emBNC accumulation in HBIG-pre-treated tumor-bearing mice and their efficiency in delivering plasmid DNA to HepG2 cells when complexed with cationic liposomes.

Main Results:

• emBNCs exhibited a 50% reduction in HBIG binding affinity compared to wtBNCs.
• emBNCs induced significantly lower HBIG production in mice than wtBNCs.
• emBNCs demonstrated effective accumulation in tumors and efficient plasmid DNA delivery to hepatocytes, even in the presence of HBIGs.

Conclusions:

• Engineered emBNCs successfully evade HBIG-mediated neutralization, overcoming a key limitation for BNC-based therapies.
• The reduced immunogenicity of emBNCs facilitates their use in pre-immunized individuals, enabling repeated administrations.
• emBNCs represent a promising platform for enhanced liver-specific gene and drug delivery, broadening the clinical utility of nanomedicine.