A U.S. Patent for “Removal of Residual Cell Culture Impurities” was awarded to Novartis on April 14th, 2020. The present invention is a method for removing Influenza Nuclear Protein (NP) from a preparation comprising virus proteins of interest, the method comprising the steps of: a. splitting a virus preparation derived from cell culture or eggs, b. adding an anionic detergent to the virus preparation under non-precipitating conditions whereby no substantial precipitation of viral proteins or DNA occurs, and c. processing the virus preparation through an ion exchange matrix, whereby the nuclear protein is bound… Learn More