A method to determine the optimal time to infect insect cellls with the baculovirus expression system

摘要

A set of batch cultures infected with the Baculovirus expression system were carried out to find out the optimal cell density, when to infect the insect cells (Sf-9), and how this correlates to the cell size and specific growth rate (#mu#, h~(-1)). By measuring the cell size before infection it is possible to predict the optimal time for infection as cell size changes, increases, during the non-infected phase of the culture. From the experiments it was found that the protein expression (production) increases as long as the cell density, at the time of infection (MOI=5), was increased up to a "critical density" where the protein expression dramatically terminated (implying a loss of"infectability" of the cells). Above this cell density level it was no longer possible to infect the insect cells and get a subsequent protein production without replenish the old medium to new fresh cell culture medium.