BACULOVIRUS EXPRESSION SYSTEM SCALEUP BY PERFUSION OF HIGH-DENSITY SF-9 CELL-CULTURES

A perfusion system based on a 4-L stirred tank bioreactor and a custom -designed tangential (cross-flow) filter was assembled to realize a sc aleup of the Baculovirus Expression Vector System (BEVS). When perfuse d with 1 to 1.5 vol/day, Spodoptera frugiperda (Sf-9) insect cell cult ures grew from 4 x 10(6) to 15 x 10(6) cells/ml over 3 to 4 days. The possibility of maintaining high specific production of recombinant VP6 protein (from bovine rotavirus) after baculovirus infection of the hi gh-density cultures was then assessed. The process consisted of a grow th phase in TNMFH + 10% FBS, followed by infection with Bac-BRV6L reco mbinant baculovirus and a shift to a low-serum (0 to 1%) medium for pe rfusion during the production phase. Multiple runs were executed, each including a battery of shaker flask controls at various cell densitie s and serum concentrations. On average, specific rVPG production in th e bioreactor amounted to 76% of that found in 20-mL shaker cultures si mulating the bioreactor's high cell density, low serum concentration, and medium renewal rate. Mechanical stress generated by cell/medium se paration in the perfusion process reduced cell growth rate but had min imal effect on rVPG production. Our results also indicated that serum concentration during the infection phase affected the rVPG specific pr oduction in a cell density-dependent fashion. Although the feasibility of the cell density scale up was demonstrated, optimization is still needed to achieve a truly cost-effective process. (C) 1994 John Wiley and Sons, Inc.