Cell culture-based vaccine production involves growing the viruses in living cells, instead of in eggs. Initially, mammalian cell lines and cell culture techniques were developed as a way to study the metabolism and growth of cells. It was soon realized that cultures of specific types of cells could be used as a way of propagating infectious disease agents, particularly viruses that can only replicate within a cell; indeed, this led to one of the first large scale uses for cell culture when in 1952 Salk developed an inactivated polio vaccine based on a live virus produced in monkey kidney cells. In recent years, it has been used for the production of vaccines for diseases such as hepatitis A, Japanese encephalitis, polio, and influenza.
Vaccine production can be splitted into a culture process and recovery/purification process. In the culture process, to produce a vaccine in large quantities, after multiplying cells in the culture process, the cells are infected with the virus, which is allowed to multiply, and then the antigen or the virus that forms the basis of the vaccine is harvested. Methods that use genetically engineered cells to produce the antigenic protein directly have also been developed. In the vaccine recovery and purification processes, the cells and contaminants are first removed from the culture fluid to obtain the supernatant containing the virus. This is then subject to virus inactivation, destruction, concentration, and filtering.