STABLE, CONTINUOUS LARGE-SCALE PRODUCTION OF HUMAN MONOCLONAL HIV-1 ANTIBODY USING A COMPUTER-CONTROLLED PILOT-PLANT

A completely automated pilot plant used for fermentation has been empl oyed with direct digital control (DDC) technology for monitoring and r egulating growth of human cells. A human hybridoma cell line (3D6) pro ducing anti-human immunodeficiency virus (HIV)-1 antibodies was used a s a model for large-scale production (300-liter airlift fermentor) in continuous culture. Parameters controlled were pH, dissolved oxygen, t emperature and the flow rate of four gases used in the process. A cont rol strategy was implemented to achieve constant fluid velocity and mi xing by maintaining the rate of gas flow at a constant level. Another advantage of this approach was that the total gas flow required for op timal fluid circulation was reduced from 1 volume gas/volume fermenter /hour (vvh) to 0.3 vvh. Use of a low flow rate eliminated the serious problems of foaming, which contributed significantly to cell destructi on, shorter filter-life and other considerations. Dilution rate was op timized at laboratory scale for maximum productivity, which results in relatively low viability. At a dilution rate of 0.0076 h(-1), a total cell density of 6-7 x 10(5) cells/ml with a viability of approximatel y 75% was maintained during long-term continuous cultivation. growth c onditions resulted in a product titer stabilized in the range of 35 mu g IgG/ml. Batchwise purification was achieved with a recovery of more than 50% and a final purification of active monoclonal antibody repre senting about 99% product. Results from isoelectric focusing and Weste rn blotting demonstrated batch-to-batch consistency of the purified hu man monoclonal antibody to HIV-1 during the continuous growth process. This approach using DDC has broad applicability for the production of high-quality biologics for use in medicine, agriculture and other dis ciplines.