4.7 AAV Production Yield in STB and Wave™ Bioreactors
The favorable features of insect cell baculovirus platform are the
ability of insect cells to grow in suspension culture at a high cell
density, a proven linear scalability, and a history of regulatory
acceptance of the platform for the production of various
biologics[9], [17]. Various reports of AAV production in either
conventional stirred-tank bioreactors (STB) (glass, stainless steel, or
disposable vessel)[48], [58], [69] or Wave™
bioreactors[69] suggest comparable yields and quality of rAAV vector
material (Table 1). The very first report of AAV production employing a
Three-Bac system in a 20L bioreactor by Meghrous et al. suggested AAV
material generation with around 3-fold improvement in cell-specific
yield of functional AAV particles in a controlled environment of
bioreactor compared to shake flask[48]. This production run
generated around 5x1012 AAV transducing units (Table
1). Subsequent reports of AAV production using modified Three-Bac system
in Wave™ and stirred tank bioreactors suggest that AAV
volumetric yield was in the range of 5x109 –
3x1010 VG/mL with a comparable consistency at various
scales of Wave™ and STB, respectively[69]. The lower volumetric
yield of AAV in Wave™ bioreactor was attributed to poor oxygen mass
transfer control in the culture. However, the vector quality, as
indicated by the ratio of genomic: transducing units, was consistent in
all production runs. Table 1 summarizes the AAV yield at various scales,
and in different IC-BEVS production reported. A schematic overview of
AAV production process using IC-BEVS platform is depicted in Figure 3.