Manufacturing of AcMNPV baculovirus vectors to enable gene therapy trials

Abstract

Over the past two decades, baculoviruses have become workhorse research tools for transient transgene expression. Although they have not yet been used directly as a gene therapy vector in the clinical setting, numerous preclinical studies have suggested the highly promising potential of baculovirus as a delivery vector for a variety of therapeutic applications including vaccination, tissue engineering, and cancer treatment. As such, there is growing interest in using baculoviruses as human gene therapy vectors, which has led to advances in baculovirus bioprocessing methods. This review provides an overview of the current approaches for scaled-up amplification, concentration, purification, and formulation of AcMNPV baculoviruses, and highlights the key regulatory requirements that must be met before gene therapy clinical trials can be initiated.

Figure 1

Flow chart of the manufacturing process of baculovirus for clinical gene therapy including existing bottlenecks.

Figure 2

Stability of concentrated baculovirus in phosphate-buffered saline with 1% glycerol after storage in −80 °C. Infectious titers were determined by plaque assay for concentrated baculovirus samples in 1% glycerol-phosphate-buffered saline prior to freezing (prefreezing), after storage for 3 weeks at −80 °C (3 weeks postfreezing), and after subsequent refreezing and storing for an additional week at −80 °C (4 weeks post freezing with additional freeze-thaw). Data are presented as mean ± standard deviation of triplicate determinations.