Adeno-Associated Virus Vector Mobilization, Risk Versus Reality.

Area of Science:

• * Gene therapy and virology, focusing on viral vector behavior and production.

Background:

• * Recombinant adeno-associated viral (rAAV) vectors are crucial for gene therapy but their potential for mobilization (spreading from cell to cell) is a theoretical safety concern.
• * Mobilization can occur independently of helper viruses or be facilitated by wild-type AAV (wtAAV) and Adenovirus 5 (Ad) coinfection.

Purpose of the Study:

• * To analyze rAAV production and mobilization in vitro, both with and without wtAAV.
• * To investigate the impact of helper viruses on rAAV production and secondary infection potential.

Main Methods:

• * In vitro analysis of rAAV production via plasmid transfection and viral transduction.
• * Mobilization assays using 293 cell lysates and coinfection with Ad and wtAAV.
• * Quantification of viral titers and transduction efficiency in secondary infections.

Main Results:

• * In vitro production showed wtAAV yielded higher titers than tested rAAV constructs.
• * Cotransfection of wtAAV and rAAV plasmids resulted in a 1:1 titer ratio, decreasing wtAAV production while increasing rAAV production.
• * Ad-independent mobilization of intact rAAV was observed, and Ad/wtAAV coinfection increased rAAV particle production >50-fold, leading to >1,000-fold transduction in secondary infections.

Conclusions:

• * rAAV mobilization is a demonstrable phenomenon under various conditions, validating theoretical safety concerns.
• * Novel wtAAV complementation enhances rAAV production, suggesting new avenues for vector manufacturing.
• * The findings underscore the necessity for developing mobilization-resistant rAAV vectors.