PHYSIOLOGICAL AND ENVIRONMENTAL-FACTORS AFFECTING THE GROWTH OF INSECT CELLS AND INFECTION WITH BACULOVIRUS

Insect cell growth can be significantly improved by close attention to the conditions used in the inoculum stages. Initial cell concentratio n, spent medium carry over and inoculum phase withdrawal significantly influenced the growth kinetics of Spodoptera frugiperda (Sf9) cells. The percentage of cells infected with wild and recombinant baculovirus AcNPV and (in the later case) the beta-galactosidase yield in fresh m edium was appreciably affected by the stage of the growth curve that c ells were in when infected and by the multiplicity of infection (MOI). However, the cell density at the time of infection and the medium con dition showed little direct influence on infectivity. There may, howev er, be an indirect influence in that these factors determine the relat ive distribution of cells in the cell cycle. The infectivity is then i n turn affected by the relative frequency of cells in the G1, S and G2 /M phases. Insect cell specific oxygen uptake rates (1.3-3.4 x 10(-17) mol per cell per s) were essentially similar to or less than those me asured for hybridoma cells. However, when Sf9 cells were infected with baculovirus, the specific oxygen uptake rate increased by up to 40%.