Influence of Agitation and Sparging on the Growth Rate and Infection of Insect Cells in Bioreactors and a Comparison with Hybridoma Culture

Abstract

Sf9 insect cells have been cultivated in paired agitated 1.4 L bioreactors with and without Pluronic F-68 and with and without sparging. The results are reported and, as appropriate, compared to those of hybridoma culture. Without sparging, the cells grew well at agitator speeds from 100 to 400 rpm (equivalent to a realistic range of specific energy dissipation rates). At the higher speeds, a small reduction in growth rate and maximum viable cell concentration was observed. This reduction was shown not to be dependent on the energy dissipation rate but to be due to bubble entrainment. These results are rather similar to those found with hybridoma cells. However, unlike hybridoma cells which grow like unsparged controls when sparged at 0.007 vvm, these insect cells at such a sparge rate show a significant reduction in growth rate and in maximum cell number. This reduction due to the presence of bubbles, whether from head space entrainment or from sparging, could be eliminated by the presence of Pluronic F-68. These insect cells have then also been infected with recombinant or wild type AcNPV. Agitation had no effect on the rate of infection, but higher levels of MOI enhanced it. Both findings support a diffusion mechanism as previously. The presence of Pluronic F-68 did not have any impact on the rate of infection and was able to prevent cell damage while agitating and sparging infected cells.