Page 1 cell culture and upstream processing 2007 05 25 by richard scarry in general the cell culture based process for virus production can be divided into two parts the upstream and the downstream process at first cells are cultivated to generate enough. In general the cell culture based process for virus production can be divided into two parts the upstream and the downstream process at first cells are cultivated to generate enough substrate during the cell expansion phase the cells are then infected to initiate the virus replication phase once the virus production has been completed and a peak in virus concentration has been reached . Finally to complete the process of upstream integration for pilot and manufacturing scale production there are rm perfusion bioreactors for seed train intensification as well as benchtop and single use stirred tank bioreactors to achieve intensified cell cultures at up to 2000 l scale and with proven cell densities of up to 200 x 10 6 cell ml at 500 l scale. News on the biopharmaceutical manufacturing industry focusing on biologics technology upstream downstream processing cell culture and regulations. Upstream processing bioprocessing begins upstream most often with culturing of animal or microbial cells in a range of vessel types such as bags or stirred tanks using different controlled feeding aerating and process strategies assays biochemicals raw materials bioreactors cell culture media expression platforms fermentation perfusion cell culture upstream contract services