Addition of nucleases directly to cell culture to facilitate digestion and clearance of host cell nucleic acids

A method for production of a flavivirus, comprising the steps of:

• a) infecting a culture of cells in a cell culture medium with the flavivirus;
• and
• b) incubating the cells in cell culture medium containing endonuclease for up to 15 days,
• wherein the endonuclease is added to the cell culture medium at any time from initial infection of the cells to prior to harvesting the cells and wherein the cells are adherent to a microcarrier.