Evidence of Pluronic F-68 direct interaction with insect cells: impact on shear protection, recombinant protein, and baculovirus production

Pluronic F-68 has been widely used to protect animal cells from hydrodynami c stress, but its mechanism of action is still debatable. Published evidenc e indicates that Pluronic F-68 interacts with cells, yet scarce information exists of its effect on recombinant protein and virus production by insect cells. In this work, the effect of Pluronic F-68 on production of recombin ant baculovirus and rotavirus protein VP7 was determined. Evidence of Pluro nic F-68 direct interaction with Sf-9 insect cells also was obtained. Maxim um recombinant VP7 concentration and yield increased 10x, whereas virus pro duction decreased by 20x, in spinner flask cultures with 0.05% (w/v) Pluron ic F-68 compared to controls lacking the additive. No differences were obse rved in media rheology, nor kinetics of growth and infection (as inferred f rom cell size) between both cultures. Hence, Pluronic F-68 influenced cell physiology independently of its shear protective effect. Cells subjected to a laminar shear rate of 3000 s(-1) for 15 min, without gas/liquid interfac es, were protected by Pluronic F-68 even after its removal from culture med ium. Furthermore, the protective action was immediate in vortexed cells. Th e results shown here indicate that Pluronic F-68 physically interacts with cells in a direct, strong, and stable mode, not only protecting them from h ydrodynamic damage, but also modifying their capacity for recombinant prote in and virus production. (C) 2000 Elsevier Science Inc. All rights reserved .