On-line monitoring of the progress of infection in Sf-9 insect cell cultures using relative permittivity measurements

The use of on-line relative permittivity (epsilon') measurements for monito ring cultures of Sf-9 cells was evaluated in a batch culture and a batch in fected with a baculovirus expressing beta-galactosidase. It was found that viable cell density a nd volume essentially accounted for all the variation in epsilon' in both non-infected and synchronously infected cultures, indi cating that the epsilon' of a cell suspension was sensitive only to changes in the viable cell population. Additionally the parameter provided clearly defined signposts of the progress of the infection. (C) 1999 John Wiley & Sons, Inc.