CAR-binding ablation does not change biodistribution and toxicity of adenoviral vectors

Area of Science:

• Gene Therapy
• Virology
• Hepatology

Background:

• Intravenous administration of adenoviral vectors frequently leads to hepatocyte transduction and subsequent hepatotoxicity.
• Hepatocytes express high levels of the coxsackie and adenovirus receptor (CAR), the primary adenovirus receptor.
• Targeting hepatocytes necessitates ablating CAR-binding, as the specific amino acid residues on the viral fiber are known.

Purpose of the Study:

• To construct a mutant adenoviral vector with CAR-binding ablation.
• To investigate the vector's biodistribution and hepatotoxicity following intravenous administration.
• To assess the impact of CAR-binding ablation on adenoviral vector infectivity and liver cell targeting.

Main Methods:

• Construction of a mutant adenoviral vector with modified fiber proteins to prevent CAR binding.
• Intravenous administration of both wild-type and CAR-ablated adenoviral vectors in a preclinical model.
• Analysis of vector biodistribution, hepatocyte transduction levels, and markers of hepatotoxicity.

Main Results:

• The CAR-ablated adenoviral vector exhibited significantly reduced infectivity compared to the wild-type vector.
• CAR-binding ablation did not affect vector biodistribution or the incidence of hepatotoxicity after intravenous administration.
• The CAR-ablated vector's infectivity was not inhibited by wild-type knob proteins, confirming CAR-binding ablation.

Conclusions:

• Ablating CAR-binding on adenoviral vectors reduces their infectivity but does not mitigate hepatotoxicity or alter biodistribution.
• Increased blood persistence of CAR-ablated vectors may contribute to sustained, albeit reduced, infectivity via alternative receptors.
• Further research is needed to identify alternative cellular receptors and develop strategies for precise adenoviral vector targeting.